Ritron RIT13-450 UHF-FM Handheld Radio Transceiver User Manual SST 454 THEORY OF OPERATION

Ritron Inc UHF-FM Handheld Radio Transceiver SST 454 THEORY OF OPERATION

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Maintenance manual

TYPE OF EXHIBIT: INSTRUCTION MANUALS

FCC PART: 2.1033 (c)(3)

MANUFACTURER: RITRON, INC.

505 West Carmel Drive

Carmel, IN 46032

MODEL: SST-444

TYPE OF UNIT: UHF-FM Handheld Transceiver

FCC ID: AIERIT13-450

DATE: July 7, 2000

Included in this exhibit is a draft of the Maintenance and Operating Manual for RITRON Model Patriot

SST-444 UHF-FM Handheld Transceiver.

Specifically, this manual includes a technical description of the SST-444 sufficient to establish compliance

with the technical standards of the applicable rule part(s).

This includes, but is not limited to, the following items required under FCC Part 2.1033 (c):

(2) FCC Identifier.

(3) A copy of the installation and operating instructions.

(4) Type of emission.

(5) Frequency range.

(6) Range of operating power, and means to provide variation in operating power.

(7) Maximum power rating.

(8) DC voltage chart.

(9) Tune-up procedure.

(10) A description of all frequency determining and stabilization circuits. A description of the circuits

used to suppress spurious radiation, limiting modulation, and limiting power.

(12) Drawing with labels for controls and complete circuit diagrams.

Signed: Michael A. Pickard - Project Engineer

TABLE OF CONTENTS

SECTION TOPIC PAGE

1. SST-444 SPECIFICATIONS

GENERAL 4

RECEIVER 5

TRANSMITTER 6

2. INTRODUCTION

GENERAL 7

Inspection 7

Model Identification 7

FCC REGULATIONS

Licensing 7

Safety Standards 7

3. BATTERY CARE

CHARGING 8

BATTERY REPLACEMENT 9

PRECAUTIONS 9

4. DESCRIPTION OF CONTROLS AND CONNECTORS 10

Fig. 2 Controls and Connectors 11

Belt Clip Installation 11

5. OPERATION

On-Off/Volume 12

Receive 12

Monitor 12

Selective Signaling Squelch 12

Battery Saver 12

Transmit 13

Channel Selection 13

WHAT THE RADIO TONES MEAN

Power On/Self Check “OK 13

Error Tones 13

Channel Select 13

Tone Squelch 13

Recharge Battery Alert 13

OPTIONAL RADIO TONES

Receiver Squelch Tone 14

Busy Channel Inhibit 14

Transmitter Time Out 14

TROUBLESHOOTING

General 15

Battery 15

Error Tones 15

Tone Coded Squelch 16

6. PROGRAMMING THE RADIO

PTT (PUSH-TO-TALK) PROGRAMMING

Placing the Radio in PTT Programming Mode 17

How To Find Out What Is Already Programmed 17

PTT Programming the Radio 18

PTT Programming Mistakes 18

Return To Normal Operation 18

Table 1 – PTT Programming Frequency Table 19

Table 2 – Quiet Call Codes and Frequencies 19

COMPUTER SOFTWARE COPYRIGHTS 19

PROGRAMMING THE RADIO USING A PC COMPUTER 20

Programmable Features 20

Description of Features 21

7. SST-444 THEORY OF OPERATION

INTRODUCTION 22

POWER SUPPLY AND VOLTAGE DISTRIBUTION 22

Power Strobe 22

Low Battery Voltage Detection 22

REFERENCE OSCILLATOR 23

SYNTHESIZER 23

Pin Numbers 23

Prescaler Divider / Synthesizer Controller 23

VCO / Buffer Amplifiers 24

Oscillator Modulation 24

DIGITAL POTENTIOMETERS 24

RECEIVER 25

RF Amplifier 25

1st Mixer 25

FM Receiver Subsystem 25

Voice / Tone Conditioning in Receiver Mode 25

Voice Band 26

Sub-Audible 26

Audio Amplifier 26

ANTENNA SWITCHING / LOW-PASS FILTER 26

TRANSMITTER 27

Keying 27

+VTX Supply 27

Power Amplifier 27

Voice/Tone Conditioning in Transmit Mode 27

Voice Band 27

Sub-Audible 28

MICROCONTROLLER 28

8. SST-444 ALIGNMENT PROCEDURE

RECOMMENDED TEST EQUIPMENT 30

RADIO PREPARATION 30

REFERENCE FREQUENCY 31

MODULATION BALANCE 31

TRANSMITTER TONE DEVIATION 31

TRANSMITTER VOICE DEVIATION 32

TRANSMITTER POWER 32

RECEIVER SENSITIVITY AND SQUELCH 32

RECEIVER NOISE SQUELCH 33

SYNTHESIZER 33

9. SST-444 VOLTAGE CHART

Measurement Conditions 34

SST-444 Voltages 34

10. SST-444 SCHEMATIC REFERENCE PARTS LIST 40

11. SST-444 CASE ASSEMBLY PARTS LIST 47

12. SCHEMATIC AND PART PLACEMENT DRAWINGS 48

IMPORTANT MAINTENANCE/REPAIR INFORMATION

Surface Mount Repair

RITRON surface mount products require special equipment and servicing techniques. Improper servicing

techniques can cause permanent damage to the printed circuit boards and/or components, which is not

covered by RITRON’s warranty. If you are not completely familiar with surface mounted component repair

techniques, RITRON recommends that you defer maintenance to qualified service personnel.

Precautions for Handling CMOS Devices

This radio contains complementary metal-oxide semiconductor (CMOS) devices, which require special

handling techniques. CMOS circuits are susceptible to damage by electrostatic or high voltage charges.

Damage can be latent, with no failure appearing until weeks or months later. For this reason, take special

precautions any time you disassemble the radio. Follow the precautions below, which are even more

critical in low humidity environments.

1) Storage/transport - CMOS devices that will be stored or transported must be placed in conductive

material so that all exposed leads are shorted together. CMOS devices must not be inserted into

conventional plastic “snow” or plastic trays of the type that are used for other semiconductors.

2) Grounding - All CMOS devices must be placed on a grounded bench surface. The technician that will

work on the radio/CMOS circuit must be grounded before handling the radio. Normally, the technician

wears a conductive wrist strap in series with a 100K Ohm resistor to ground.

3) Clothing - Do not wear nylon clothing while handling CMOS circuits.

4) Power off - Remove power before connecting, removing or soldering a PC board that contains CMOS

devices.

5) Power/voltage transients - Do not insert or remove CMOS devices with power applied. Check all

power supplies to be used for testing CMOS devices, making sure that no voltage transients are

present.

6) Soldering - Use a grounded soldering iron for soldering CMOS circuitry.

7) Lead-straightening tools - When straightening CMOS leads, provide ground straps for the tool used.

PC Board Removal - Special Tool

RITRON recommends using a knurled nut tool to remove the slotted knurled nuts that secure the charge

and audio jacks on top of the radio. You will need two sizes of this tool, one for each jack size. Mouser

Corporation  is one source, stock number 382-0004 (2.5mm jack) and 382-0006 (3.5mm jack). You can

reach Mouser sales and distribution center at 1-800-346-6873.

Properly Attach the Synthesizer Shield

The synthesizer shield should not be removed, unless a component must be replaced. This shield is

soldered to the main PC board.

Re-assembly - Speaker Magnet, Battery Voltage on Connector Pin

The speaker magnet will pick up clipped leads and other small metal objects from your bench top. Even

tiny objects on the diaphragm will cause the speaker to buzz. Make sure the speaker is free of foreign

objects before reassembling the radio.

Radio Transmitter Power Measurements

The SST-444 was designed to produce a minimum of 3.5 Watts of Transmitter power at nominal battery

voltage (+7.2 VDC), throughout the radio’s operating frequency range. Measurements are made with the

RITRON SST-SRVBD RF service module connected to the radio antenna terminal. The transmitter was

designed with close tolerances to prevent RF power output from exceeding specifications and reducing

battery life.

SST-444 SPECIFICATIONS

GENERAL

FCC ID: AIERIT13-450

FCC Rule Parts: 22, 74, 80, 90

Frequency Range: 460 to 470 MHz standard

Max. Freq. Separation: 10 MHz

RF Channels: Conventional: 4 Channels, Independent TX/RX frequencies.

Synthesizer Step Size: 12.5 KHz

Frequency Stability: +/-2.5 PPM (-30 to +60 C) TX/RX

Tone/Code Signaling: CTCSS (Quiet Call)

Digital Coded Squelch (Digital Quiet Call)

Power Supply: +7.5 VDC, 800 mAH rechargeable NiCd battery pack standard

+7.5 VDC, 1500 mAH rechargeable MiMH battery pack optional

Battery Drain:

Standby: 52 mA

Sleep: 12 mA

Avg. Standby with Power Saver: 24 mA

Receive: 125 mA

Transmit: 1500 mA @ 4 Watts

500 mA @ 1 Watt

Battery Life:Standard battery (800 mAH) @ 90/5/5 Duty Cycle

8.2 Hrs, Battery Saver On, TX High Power

16.8 Hrs, Battery Saver On, TX Low Power

6.2 Hrs, Battery Saver Off, TX High Power

10.2 Hrs, Battery Saver Off, TX Low Power

High capacity battery (1500 mAH) @ 90/5/5 Duty Cycle

13.3 Hrs, Battery Saver On, TX High Power

27.3 Hrs, Battery Saver On, TX Low Power

10.2 Hrs, Battery Saver Off, TX High Power

16.7 Hrs, Battery Saver Off, TX Low Power

Dimensions: 4.75”H x 2.2”W x 1.43”D

Weight: 11.5 oz. with battery pack

Enclosure Material: Lexan Polycarbonate

Environmental: Splash resistant and shock and vibration per RITRON Drop Test

(6 ft. drop onto concrete on all six sides)

Antenna Fitting: 1/4" - 32 x 1/4" threaded

External RF Test Jack: Antenna connector with RITRON SST-SRVBD test device

SST-444 SPECIFICATIONS

GENERAL

Earphone Jack: 3.5 mm, disconnects the internal speaker for external earphone,

speaker / microphone, or headset. Also provides cable connection

for PC programming.

Microphone/PTT/Chg Jack: 2.5 mm, for external speaker/microphone, headset or RITRON

model BC-A wall charger

Push Button Controls:On/Volume Up

Volume Down/Off

PTT

Channel

Speaker Beep Indicators:

On/Volume UP Single beep when radio is turned on, followed by increasing audio

to adjust volume.

Volume Down/Off Decreasing audio to adjust volume, with two tones when unit is

turned off.

Both Volume Buttons Alternates between Tone Squelch (single beep) and Carrier

Squelch (two beeps). If both buttons are held down until the radio

beeps repeatedly, squelch will be disabled.

Channel Number of beeps indicates channel.

RECEIVER

Wide band Model Narrow band Model

Modulation Acceptance: +/- 7.0 KHz +/- 3.75 KHz

Sensitivity (12 dB SINAD): 0.25 µV 0.25 µV

Adjacent Channel (EIA): -60 dB -50 dB

Spurious Rejection: -60 dB -60 dB

Image Rejection (EIA): -70 dB -70 dB

Intermodulation (EIA): -56 dB -57 dB

Noise Squelch Sensitivity: Programmable per channel, factory set for 12 dB SINAD

Frequency Response: 300 - 3000 Hz, de-emphasized

Audio Output 1 Watt into 8 Ω, with less than 5 % THD @ the earphone jack

Receiving System: Dual conversion superheterodyne

I.F. System: 1st - 43.65 MHz 2nd - 450 KHz

L.O. Injection: Low side

QC/DQC Decode Time: per EIA Standards

SST-444 SPECIFICATIONS

TRANSMITTER

RF Power Output: Programmable per channel for high or low power

High : 4 Watts (3.5 Watts minimum @ +7.2 VDC)

Low: 1 Watt

Wide Mode Narrow Mode

Emission Designator: 16K0F3E 11K0F3E

Deviation: +/- 5.00 KHz +/- 2.50 KHz

FM Hum and Noise: -43 dB -37 dB

Audio Distortion: < 3 % < 6 %

Spurious and Harmonics: -50 dBc

Audio Response: Meets FCC and EIA requirements

Time-out Timer: 60 seconds, programmable

INTRODUCTION

GENERAL

RITRON's SST-444 handheld is a small, programmable two-way radio, designed to operate in the 460-

470 MHz professional FM communications band.

This handheld features push-button operating controls, with the Push-To-Talk and Channel buttons on

one side of the radio. The On / Volume Up and Volume Down / Off, volume and monitor controls are on

top.

Each radio can be “dealer or factory” programmed to contain a unique set of operating frequencies and

options. Selective signaling options include Quiet Call (CTCSS) and Digital Quiet Call (DCS). Transmitter

power, operating bandwidth and battery saver are among the options programmable on a per channel

basis.

Inspection

Each radio package should include a radio, antenna, rechargeable battery pack, belt clip and any optional

accessories ordered. Examine the equipment immediately after delivery and report any damages to your

shipping company.

Model Identification

The SST-444 model, serial number and FCC Identification are displayed on a label located on the back of

the radio beneath the belt clip.

FCC REGULATIONS

Licensing

The FCC requires the radio owner to obtain a station license for his radios before using them to transmit,

but does not require an operating license or permit.

The station licensee is responsible for ensuring that transmitter power; frequency and deviation are within

the limits specified by the station license. The station licensee is also responsible for proper operation and

maintenance of the radio equipment. This includes checking the transmitter frequency and deviation

periodically, using appropriate methods.

Safety Standards

The FCC (with its action in General Docket 79-144, March 13, 1985) has adopted a safety standard for

human exposure to radio frequency electromagnetic energy emitted by FCC regulated equipment.

RITRON follows these safety standards, and recommends that you observe the following guidelines:

•DO NOT hold the radio such that the antenna is very close to or touching exposed parts of the body,

especially the face or eyes, while transmitting. Keep the radio vertical, two to three inches away while

talking into the microphone.

•DO NOT press the Push-To-Talk except when you intend to transmit.

•DO NOT operate radio equipment near electrical blasting caps or in an explosive atmosphere.

•DO NOT allow children to play with any radio equipment that contains a transmitting device.

•Repair of RITRON products should be performed only by RITRON authorized personnel.

BATTERY CARE

The handheld is powered by a rechargeable battery, which fits into the radio case (see FIG-1).

CHARGING

The battery pack can lose its charge during storage and shipment, and should be fully charged before the

radio is used. Thereafter, the battery should be charged overnight after each day of use, to ensure peak

radio performance for the next day. Using the cube charger (model BC-A), the battery should charge

completely in 12 hours.

Note: A new battery must be cycled (charged and discharged) several times before it will reach its

maximum charge capacity.

To charge the battery using a RITRON cube charger - plug the charger cord into the smaller of the two

jacks on top of the radio. Then plug the cube into a 110 VAC outlet. The green lamp lights while the

battery is charging, and should go off only when the cube is unplugged.

Two charger contacts, visible through the bottom of the radio case, allow the battery to be charged using

an optional RITRON drop-in charger (model BCPS-FS). The battery pack may be charged inside or

outside of the radio case.

To charge the battery using a drop-in charger (model BCPS-FS) - plug the drop-in charger into a 110 VAC

outlet. Set the portable or battery into the charger. Each battery contact must rest on a charger contact

pin.

Typically, a battery pack’s service life is one year. To ensure maximum service life, follow these

guidelines:

•Do not discharge a battery that is already “run down.” If the battery cannot power your radio, recharge

the battery.

•Do not overcharge a battery. The standard battery should not be left to charge continuously.

•Before storing a battery, charge it for 16 hours. Thereafter, charge the battery for 16 hours once every

30 days.

With daily use and recharging, a battery’s service life is about one year. It is time to purchase a new

battery:

1) When the radio’s transmitter coverage decreases or does not work at all.

2) When the radio quits working after just a few hours of use, even with a full overnight charge.

3) When the battery is more than two years old. The date of manufacture is stamped on every battery.

The first two digits indicate the year, the last two digits the week.

BATTERY CARE

BATTERY REPLACEMENT

To take the battery out of the radio, remove the battery door pictured in FIG-1. Use the pull-tab to remove

the battery.

Slide the replacement battery into the radio case. Make sure the spring contacts are inserted between the

battery and paper insulator. The contacts must not touch the radio PC board.

PRECAUTIONS

•Use only RITRON-supplied chargers; other chargers might cause fire, explosion, or other damage to

the radio.

•Do not "fast-charge" a brand new battery pack. Otherwise, the battery might be damaged.

• Once the battery has been charged fully using the normal rate, the fast rate may be used thereafter.

•Do not fast-charge a battery pack that is fully charged. This can shorten battery life.

•Do not charge or replace a battery in an explosive atmosphere. Contact sparking can ignite an

explosion.

•Do not dispose of a battery in fire. An explosion might result.

•Do not charge the battery in temperatures colder than about 45°F. Electrolyte leakage can occur and

ruin the battery.

•Charging in temperatures above approximately 95°F will not harm the battery, but can reduce its

charge capacity.

Fig. 1

Battery Replacement

DESCRIPTION OF CONTROLS AND CONNECTORS

Antenna

The flexible antenna radiates and receives radio signals. Before using the radio, be sure the antenna

base is threaded fully into the radio’s antenna bushing.

VHF and UHF antennas are not interchangeable. Use only the antenna type packaged with the radio. A

VHF antenna is pictured in FIG-2. (The UHF antenna is smaller in diameter.)

On/Volume Up

This button switches on the radio, then increases the volume if you continue to press.

Off/Volume Down

This button decreases the volume, then shuts off the radio if you continue to press.

Channel Select

Pressing this button selects the next channel. When the maximum number of channels is reached and

you press this button, the radio resets to channel 1.

Speaker

The speaker allows you to hear calls on your channel.

Push-To-Talk Button

The PTT activates the transmitter, and must be held down while you talk into the microphone. Release

the PTT button to receive.

Microphone

The microphone converts your voice into electrical impulses, which are carried with your broadcast to

receiving radios. Hold the radio about two inches away and talk into the microphone while transmitting.

Shouting does not improve the listener’s reception.

Audio Accessory Jack

This jack connects speaker audio to optional accessories, such as a remote speaker/microphone or an

earphone. For accessories that have a two-plug connector, the smaller plug is inserted into the charge

jack.

This jack is also used to program the radio using the optional PC programming kit.

Charge Jack

The battery may be charged through this jack using a standard RITRON wall socket charger cube.

This jack also connects microphone audio to the optional remote speaker/microphone.

Battery Access (Case Bottom)

The battery door on the case bottom may be removed to access the battery. (Refer to the battery section

of this manual.)

Drop-in Charger Contacts

Two charger contacts in the bottom of the SST-444 radio case allow the battery pack to be charged using

an optional RITRON drop-in charger (model BCPS-FS).

Jack Cover

This rubber cover seals out dust and moisture, etc. Snap the cover into the audio accessory and charge

jack openings when the jacks are not being used.

DESCRIPTION OF CONTROLS AND CONNECTORS

ON OFF/HOLD

VOLUME

Belt Clip Installation

If you are going to attach the belt clip to the handheld, follow these instructions:

1) The belt clip is fastened to the radio case back with the Philips head screw provided. Use the screw

included, since a longer screw might damage the radio’s electronics.

Do not use petroleum solvents of any kind on the radio. These can corrode the case.

2) Place the belt clip on top of the radio case back, with the screw hole in the aligned with the hole in the

radio case.

3) Using the screw that came with this accessory, attach the clip to the radio.

Antenna

Vol Down/Off

On/Vol Up

Audio Accessory Jack

Jack Cover

Charge Jack

Speaker

Microphone

Push-to-Talk

Channel Selector

Battery Access Door

(Case bottom) Battery Charger Contacts

(Case bottom)

Fig. 2 Controls and Accessory Connectors

OPERATION

On-off/Volume

To switch on the radio - press the on/volume up button.

To adjust the volume - press the volume up button until you reach the desired level. You should hear

noise and any broadcasts on the channel.

To turn off the radio - press and hold the off/volume down button until two tones sound.

To determine whether the radio is on - press the volume down button. If the radio is on, noise or activity

on the channel is heard.

Receive

To hear calls from other users - adjust the volume as desired. The radio can receive broadcasts while the

Push-To-Talk button is not being pressed. Whether or not you hear these broadcasts depends upon the

squelch settings.

There are two types of squelch used in the SST-444 portable. First is carrier squelch. This lets you hear

all broadcasts on your channel strong enough for the radio to detect, and silences noise. Second is one of

the selective signaling or “tone squelch” formats available on the SST-444. This allows you to screen out

“on-channel” broadcasts that do not carry the correct code programmed for the radio.

Note: It is possible that the beginning of a call might be missed while the radio is in battery saver mode. If

this happens, ask the caller to repeat his message.

Monitor

To monitor the channel - press one of the volume control buttons. When you press the volume up or the

volume down button, squelch turns off and all radio traffic on the channel (and noise) sounds in the

speaker.

Selective Signaling Squelch

To activate tone squelch - simultaneously press both of the volume buttons. Hold for a second or two

before releasing. When tone squelch is turned on, the handheld sounds one beep. When carrier squelch

is on, the radio emits a "double beep."

Note: If you continue to hold down the volume buttons after the beep (or double beep), the radio will start

beeping repeatedly. This means that squelch is turned off. Release the buttons. To restore squelch,

press and hold both of the volume buttons until the radio sounds a beep or double beep.

Battery Saver

The handheld has a programmable "battery saver" feature that conserves battery power. The battery

saver constantly checks the radio's transmitter, receiver and controls for activity. If a number of seconds

pass without the receiver detecting a call, and without the user operating a control, this feature removes

power from most of the radio.

During this "off-time," any activity restores full power. Every few fractions of a second, the battery saver

applies power to the receiver, checking for broadcasts. It is possible that the first part of an incoming call

might go unheard before activity is detected and power restored. If this happens, the caller can repeat his

message. Once "radio contact" is made, normal unhurried conversation can follow.

OPERATION

Transmit

Normally, you should not transmit until no one is talking on the channel.

To transmit - hold down the Push-To-Talk button and, with the radio a couple of inches away, talk into the

microphone. Speak in a normal tone, since talking louder will not improve the listener’s reception.

Channel Selection

To change channels - press and release the channel button. The radio will beep a number of times equal

to the new channel number. For example, if you select channel 2, the handheld will beep twice. If the

highest channel number is selected and you press the channel button, the radio will reset to channel 1. A

one-channel radio will beep only once when you press the channel button.

WHAT THE RADIO TONES MEAN

The handheld responds to certain instructions by sounding a beep or series of tones. These tones can tell

you whether the radio is working as you expect.

Power On/Self Check “OK”

When the handheld is turned on, it will run a quick “self test.” Once the internal system checks confirm

basic functions, the radio sounds a brief “confirmation tone.” The radio is then ready to use.

Error Tones

However, if the “self test” detects a diagnostic error, an error tone sounds. Alternating tones (the second

is longer and lower pitched) indicate the radio frequency synthesizer is malfunctioning. Turn off the radio

and try again. A long, low-pitched tone means the battery voltage is too low to operate the radio. In this

case, recharge the battery. If you cannot correct a problem, consult an authorized Ritron service facility or

Ritron.

Channel Select

When the channel button is pressed, the radio beeps a number of times equal to the channel number

selected.

Tone Squelch

When you press and hold both Volume buttons at the same time, a single beep will sound to indicate that

tone squelch is on. A "double beep" means that carrier squelch is on.

Recharge Battery Alert

As the battery voltage approaches the minimum required “operating voltage” the radio will emit a short

beep every minute to alert the user that the battery will soon need recharging. Once the battery charge

drops below the required "operating voltage," the radio emits a long, low tone and turns itself off. If you

turn the radio back on, it will beep again and shut itself off. Recharge the battery.

OPERATION

OPTIONAL RADIO TONES

The SST-444 can be programmed using the RITRON PC Programmer for optional alert tones.

Receive Squelch Tone

A short tone sounds at the end of each received transmission to indicate that you may transmit.

Busy Channel Transmit Inhibit

If a user is transmitting on your radio frequency without your tone, you will not be allowed to transmit. The

radio will beep a series of long, low tones while the PTT is held down (like a busy signal).

Transmitter Time Out

A low tone followed by a higher-pitched tone sounds and the transmitter automatically shuts off if you hold

down the PTT button longer than the programmed Time-out. The radio automatically switches to receive

mode. Authorized service personnel can turn off this feature.

OPERATION

TROUBLESHOOTING

If you have trouble operating the handheld, review the radio controls and operation sections. If you think

the radio is malfunctioning, check the table below.

Problem Possible Solutions

GENERAL

The radio does not work at all. Make sure that the battery is installed correctly, as shown

in FIG-1.

Recharge or replace the battery. (See note 1.)

Operating features do not work exactly The radio has been factory or dealer programmed for

As expected. customized operation.

Reception is poor. Move to a different location. (Note 2.)

Confirm that the proper antenna is connected to the radio.

(See p. 11, "Antenna.")

You cannot hear calls from other radios. Turn off tone squelch. (See Note 3.)

Be certain your radio receives on the same as the caller

transmits. (Note 4.)

Recharge the battery. (Note 1.)

Your calls cannot be heard in other radios. Make sure that your radio transmits on the receive

frequency of the radio(s) you want to call. (Note 4.)

Recharge the battery. (Note 1.)

Battery

The battery loses its charge sooner than Review the battery charging instructions.

expected. Conserve the battery. (Note 5.)

If the radio is used in extreme cold, warm the radio under

your coat. (Note 6.)

Replace the battery. (Note 1.)

Error Tones

An error tone sounds when the radio is first See "Error Tones" in the Operation section.

switched on.

An error tone sounds while you are talking Refer to “Error Tones”

(and the transmitter shuts off).

OPERATION

TROUBLESHOOTING

Problem Possible Solutions

Tone Coded Squelch

You cannot screen out calls from users Make sure the channel is programmed with tone squelch.

outside of your tone group. Activate Tone (coded) squelch. (Note 7.)

You cannot hear Tone coded messages Confirm that the channel is programmed to detect the

while in Tone (coded) squelch. same code as the calling radio(s) transmits. (Note 7.)

Others in your tone group cannot hear your Verify that you transmit the same code as the radio(s) you

tone coded messages. call are programmed to detect. (Note 7.)

Notes

1) Try a battery pack from a working radio. If the radio in question works with that pack, the original

battery is suspect. Charge the suspect battery as recommended in this manual. Then, if the charged

original battery cannot power the handheld, try charging again with another charger. If the battery still

doesn’t hold a charge, the pack should probably be replaced. However, if the battery appears to be

good after you try the second charger, the first charger might be faulty. If you think that an accessory

is not operating properly, contact your dealer or RITRON. (Radio accessories come with a 90-day

limited warranty.)

2) Reception can often be improved by moving a short distance. This effect is more noticeable inside of

buildings. The range of these portables equipped with a standard battery pack is about two miles

(line-of-sight).

3) If your radio does not detect calls from other radios on the channel, turn off tone squelch. (Press both

Volume buttons at the same time - a double beep means that tone squelch is off.)

4) If you want to hear a call, you must select a channel that is programmed to receive the caller’s

transmit frequency. If you want to call another unit, you must select a channel that is programmed to

transmit the other radio’s receive frequency. However, if you use a repeater, your channel must be

programmed to work with the repeater’s transmit and receive frequencies. (A radio channel can hold

two separate operating frequencies, one for Receive, the other for Transmit.)

5) Maximum power drain occurs while the radio transmits, so don’t hold down the Push-To-Talk button

more than necessary. Battery power is used while the handheld is left on to receive calls. If practical,

switch off the unit.

6) In extreme cold, a battery’s charge capacity is greatly reduced. If you use the radio in very cold

weather, periodically warm the portable underneath your coat if possible. An optional remote

speaker/microphone would allow you to keep the radio under your coat while transmitting and

receiving.

7) In order for radios to communicate using Quiet Call, they must be programmed with the same tone

code. Each code is unique, and your radio will respond only to the code programmed.

Press and hold both volume buttons at the same time. A single beep means that tone squelch is on.

A double beep means that tone squelch is off.

PROGRAMMING THE RADIO

Each SST-444 may be programmed to operate on up to 4 channels. The SST-444 may be programmed

using its Push-to-Talk switch or an optional RITRON programming kit.

PTT (PUSH-TO-TALK) PROGRAMMING allows you to program any channel to one of the radio

frequencies listed in Table 1 and any Quiet Call code listed in Table 2. The radio will transmit and receive

on the programmed table frequency and QC code.

PC PROGRAMMING allows you to program any frequency within the band and channel spacing of the

radio model. This method also lets you customize the handheld with optional operating features.

PTT (PUSH-TO-TALK) PROGRAMMING

Placing the Radio in PTT Programming Mode

1. Turn off the radio by pressing the Volume Down button until the “radio off” prompt sounds.

2. Press and hold the PTT button.

3. While holding the PTT button, press and hold the Volume On button until a rapid beeping is heard in

the speaker.

4. Release the PTT and Volume On buttons. A series of three ascending tones will sound in the speaker

indicating that the radio is in PTT program mode.

Note: If the radio will not enter PTT program mode, this feature has probably been turned off using the

optional PC programming kit.

How to Find Out What Is Already Programmed

1. Place the radio in PTT programming mode as described above.

2. Press the Channel button to select the radio channel you would like to read out.

3. Press the Volume Up button.

4. The radio will sound a series of beeps, pause, and then begin another series. Four series of beeps

will be heard, with each series representing a digit. The number of beeps in a series is equal to the

digit. (10 beeps = the digit 0)

5. Write down each digit while the radio pauses. List the digits in the order that you hear them.

6. The first two digits represent the frequency as shown in Table 1.

7. The second two digits represent the QC (CTCSS) tone frequency as shown in Table 2.

Note: If you are unable to read out a channel, it has probably been programmed using the PC

programming kit to a frequency not contained in Table 1.

PROGRAMMING THE RADIO

PTT Programming the Radio

Four valid digits must be entered for the radio to accept PTT programming. The first two digits entered is

the frequency code from Table 1, followed by the two digits for the QC code from Table 2.

1. Place the radio in PTT programming mode as described above.

2. Press the Channel button to select the radio channel you would like to program.

3. Enter the first digit by pressing the PTT button the number of times equal to the digit’s value.

(To enter the digit 0, press the PTT ten times.)

4. Pause after the digit is entered, a tone will sound indicating that the digit has been accepted.

5. Enter the second, third and fourth digits using the same method as the first digit.

6. Press the Volume Up button to enter the new channel programming. The radio will sound a

confirmation tone to indicate that programming has been accepted.

PTT Programming Mistakes

Invalid Entries An error tone means that you tried to save an invalid entry. No programming

changes are made in this case. A triple tone will sound next indicating that the

radio is still in programming mode, and ready for an entry.

PTT Entry Mistakes If you press the PTT five times when you intended four, for example, or if you just

lose count, do not press the Volume Up button to store the entry. Instead, start

over by turning the radio off and placing the radio in programming mode again.

Return To Normal Operation

After you finish programming, turn the radio off and then on again. The radio will beep when it is ready for

normal operation.

PROGRAMMING THE RADIO

Table 1 – PTT Programming Frequency Table

Code Frequency Description Code Frequency Description

01 467.7625 J 11 462.6250 Black Dot

02 467.8125 K 12 462.6750 Orange Dot

03 464.5500 Yellow Dot 13 464.3250

04 464.5000 Brown Dot 14 464.8250

05 467.8500 Silver Star 15 469.5000

06 467.8750 Gold Star 16 469.5500

07 467.9000 Red Star 17 463.2625

08 467.9250 Blue Star 18 464.9125

09 469.2625 19 464.6000

10 462.5750 White Dot 20 464.7000

Table 2 – Quiet Call Codes and Frequencies

QC Freq QC Freq QC Freq QC Freq

Code (Hz) Code (Hz) Code (Hz) Code (Hz)

01 67.0 16 114.8 31 192.8 46 189.9

02 71.9 17 118.8 32 203.5 47 196.6

03 74.4 18 123.0 33 210.7 48 199.5

04 77.0 19 127.3 34 218.1 49 206.5

05 79.7 20 131.8 35 225.7 50 229.1

06 82.5 21 136.5 36 233.6 51 254.1

07 85.4 22 141.3 37 241.8

08 88.5 23 146.2 38 250.3

09 91.5 24 151.4 39 69.4

10 94.8 25 156.7 40 159.8

11 97.4 26 162.2 41 165.5

12 100.0 27 167.9 42 171.3

13 103.5 28 173.8 43 177.3

14 107.2 29 179.9 44 No Tone

15 110.9 30 186.2 45 183.5

COMPUTER SOFTWARE COPYRIGHTS

The RITRON, Inc. products described in this manual include copyrighted RITRON, inc. computer

programs. Laws in the United States and other countries grant to RITRON, inc. certain exclusive rights in

its copyrighted computer programs, including the exclusive right to distribute copies of the programs,

make reproductions of the programs, and prepare derivative works based on the programs. Accordingly,

any computer programs contained in RITRON, inc. products may not be copied or reproduced in any

manner without the express written permission of RITRON. The purchase of RITRON, inc. products does

not grant any license or rights under the copyrights or other intellectual property of RITRON, inc., except

for the non-exclusive, royalty fee license to use that arises in the sale of a product, or as addressed in a

written agreement between RITRON, inc. and the purchaser of RITRON, inc. products.

PROGRAMMING THE RADIO

PROGRAMMING THE RADIO USING A PC COMPUTER

RITRON’s programming kit allows programming of the SST-444 model radios using a PC compatible

computer. An adapter cable connects the radio to a computer’s serial communications port. Once the

cable is hooked up, the user inserts the diskette provided into his computer’s floppy disk drive and loads a

software program.

This program transfers data between radio and computer memory, and includes on-screen instructions

and help. Radio data may be saved to the computer’s hard disk in order to program other radios.

The PC Programming Kit Includes:

1) Ritron Transceiver programming software, which is contained on 3.5" diskettes.

2) Installation instructions and a registration form.

3) Ritron PC to radio adapter cable, which is terminated at one end with a DB-25F connector, at the

other end with a modular plug. The DB-25 plugs into the computer’s serial port, the modular plug into

the SST-SRVBD modular jack.

4) An adapter for use with SST-444 portables. This adapter mates the modular plug to a 3.5 mm plug,

for connection to the handheld audio jack.

The PC Programming Kit Requires:

A PC compatible computer with Windows 95 or later. The computer must have an RS-232 serial port

available. A hard disk drive is recommended.

Programmable Features

The following features may be programmed on a per channel basis, or will affect all channels together.

Feature Range Standard Setting Per Channel

Automatic Inactivity Turn-off Yes - No Yes

Battery Saver Enable Yes - No Yes

Battery Saver Off Time - -

Beep Volume Level Fixed – Controlled Fixed

Beep Fixed Volume Level - -

Busy Channel Transmit Inhibit Yes - No No √

Carrier Only, No Tones or Codes - - √

Channel Selection Mode Increment - Enter Increment

Digital Tone Invert RX Yes - No No √

Digital Tone Invert TX Yes - No No √

Digital Quiet Call (DCS) - - √

Disable Monitor Yes - No No √

Channel Beep Rate Slow - Fast Slow

Narrow Band Channel Yes - No No √

Quiet Call (CTCSS) See Table 2 - √

Quiet Call Encode Only Yes - No No √

Receive Squelch Tone Yes - No No √

Squelch Tightener Yes - No No √

Transmit Power Low - High High √

Transmit Time Out Timer (60 s) Yes - No Yes

Turn On To Medium Volume Level Yes - No Yes

PROGRAMMING THE RADIO

Descriptions of Features

Automatic Inactivity Turn-off - The radio automatically shuts itself off if four hours go by without the

microcontroller detecting input from the volume, PTT or channel controls.

Battery Saver - Enabling this option allows the radio to go into battery saver mode when the radio remains

idle. The power strobe begins after eight seconds of inactivity.

Battery Saver Off Time - This is the cycle time that the radio is off in battery saver mode before it checks

for a received signal. A long Battery Saver Off Time may cause the user to miss the beginning of the first

message when in battery saver mode.

Busy Channel Transmit Inhibit - This keeps the radio from broadcasting if the channel is busy, and is often

used in conjunction with Disable Monitor. If you press the PTT when the channel is busy with a signal not

intended for your radio (not carrying your tone code), this feature sounds a "busy" tone in the speaker and

keeps the transmitter turned off.

Channel Selection Mode - This feature allows the channel selector to increment or enter the channel. The

channel number is "beeped out" when the channel button is first pressed. The channel is not changed. In

increment mode the radio is changed to the next available channel if the channel button is pressed again

within three seconds. In enter mode the user must press the channel button the number of times equal to

the channel they wish to select.

Digital Quiet Call RX Invert - The programmed code is inverted for receive mode only.

Digital Quiet Call TX Invert - The code is inverted for transmit mode.

Disable Monitor - This function may be programmed to keep the radio user from listening to other

licensees on a shared channel. QC, DQC or trunking must be used with this option (although, not the

Encode Only feature).

Quiet Call (CTCSS) - Programming a Quiet Call code allows you to screen out transmissions that do not

carry your code. Your code is broadcast when you press the PTT to make a call.

Quiet Call Encode Only - The Quiet Call code programmed for the channel is transmitted with your calls.

However, Quiet Call is turned off during receive mode, allowing all traffic on the channel to be heard.

Receive Frequency - The radio frequency that receives broadcasts from other units.

Receive Squelch Tone - The receiving radio beeps at the end of each received transmission.

Squelch Tightener - This feature reduces distant "co-channel" or other interference for channels that are

not programmed with Quiet Call. Carrier squelch is set for maximum sensitivity at the factory, but may be

adjusted to mute weak signals

Transmit Time Out Timer - This feature automatically shuts off the transmitter (ending your call) if you hold

down the PTT button continuously for 60 seconds. The radio sounds a tone when the transmitter shuts

off.

Turn On To Medium Volume Level - The volume level is at mid-range when the radio is first turned on.

Normally, the volume level is low when the radio is turned on.

SST-444 THEORY OF OPERATION

INTRODUCTION

The SST-444 is a four-channel handheld transceiver built on a single multi-layer printed circuit board.

Both sides of the main printed circuit board are populated with components, with the bottom side

containing only surface mounted components.

The SST-444 is frequency synthesized, with all functions of the radio controlled by microcontroller.

POWER SUPPLY AND VOLTAGE DISTRIBUTION

The SST-444 is powered by an internal 6-cell rechargeable battery pack. The battery pack supplies power

to the radio via two contact terminals that are connected to the PCB through P302. F301 is a 3A fuse in

series with P302 for short circuit protection. The battery pack may be charged through 2.5 mm charge

jack J301 via CR302 and F301. Zener diode CR301 prevents the batteries from discharging through the

charger accessory, stops a reverse voltage from being applied to the battery pack through J301, and

prevents a high voltage from being applied to the radio circuitry.

SW301 ON/VOL UP switched is pressed to switch on the SST-444, turning on voltage pass transistor

Q304 via R302. Q304 supplies power to IC309, a +5 VDC regulator used to power microcontroller IC301.

Pin 13 of IC301 turns on Q303, which keeps Q304 turned on after SW301 has been released. Power is

removed from the SST-444 by pressing the VOL DN/OFF switch SW302 until a beep is heard from the

speaker, at which time Q304 is turned off.

+5 VDC regulator IC309 supplies power directly to microcontroller IC301, bilateral audio gates IC304,

reference oscillator Y302, synthesizer IC401, and PTT detect transistor Q302.

The T/R output at Pin 11 of IC301 lets Q101 switch the regulated +5 VDC to the receiver. Pin 11 of IC301

will also turn on Q202, which turns on voltage pass transistor Q204. With Q204 emitter connected to the

+VBATT battery supply, the collector output is connected to the emitter of Q202 through voltage divider

R202/R203, whose values are selected to limit the TX+V voltage to +6 VDC.

Power Strobe

The SST-444 handheld includes a power strobe feature, which reduces battery current drain by

periodically removing voltage from part of the radio. The strobe off cycle time is programmable using the

PC Programming Kit. The +5VSW power strobe output at Pin 10 of IC301 controls Q306, which switches

the regulated +5 VDC to the audio processing circuitry and the synthesizer circuitry. This includes IC303A

2.5 VDC (Vag) for bias on audio processing circuitry, IC303C audio high pass filter, IC308 and IC305A

audio low pass filter for sub-audible frequencies, IC305B audio limiting amplifier, IC306 digital

potentiometers, IC303B audio summing node amplifier, and IC303D audio low pass filter.

Low Battery Voltage Detection

Battery voltage is measured at A/D input Pin 16 of IC301 through voltage divider R303/R305. The radio

will emit a periodic beep if low battery voltage is detected, and will turn the radio off if the battery voltage

drops below +5 VDC. This is to protect the microcontroller and its EE memory from corruption due to low

supply voltage.

SST-444 THEORY OF OPERATION

REFERENCE OSCILLATOR

Reference oscillator Y302 is a 1.5 ppm temperature controlled, voltage controlled oscillator (TCVCXO)

operating at 14.4 MHz. The Pin 4 output of the TCVCXO provides a reference for the frequency

synthesizer IC401 at Pin 20. IC401 is programmed to provide an output at Pin 1 that is ¼ of the reference

(3.6 MHz), which is applied as a reference oscillator to Pin 27 of IC301 microcontroller. The Y302 pin 4

output is also multiplied up to 43.2 MHz by Q105 and its associated circuitry to provide a receiver 2nd local

oscillator signal.

SYNTHESIZER

The SST-444 radio is built around a common phase-locked loop (PLL) that consists of a voltage-controlled

oscillator (VCO) and a frequency synthesizer. The PLL generates both the receiver 1st local oscillator and

transmitter carrier signals. Control signals from microcontroller IC301 and Reference oscillator Y302 are

routed to frequency synthesizer IC401 per the following chart:

Pin Numbers

Clock Data Latch LD T/R SW REF IN REF OUT +5SW +5V

IC301 12 5 20 12 11 - 27 10 -

Y302-----4--2

IC401 18 19 17 2 - 20 1 12 5, 14

Q404, CR401, C414 and associated components provide a filtered supply for the VCO oscillator and

buffer amplifiers.

Prescaler Divider / Synthesizer Controller

IC401 contains both a prescaler and synthesizer controller. The prescaler squares and divides the VCO

output present at pin 11 by either 64 or 65, determined by a synthesizer controller logic signal. The exact

number of times the prescaler is instructed to change divisors is determined by the channel frequency.

IC401 contains a digital phase detector that works as follows: when an operating channel is changed or

the receive/transmit mode switched, a new synthesizer operating frequency is selected. Microcontroller

IC301 clocks new data into IC401 internal buffer in synchronization with clock pulses. The channel

information is stored in EE memory of IC302 and is loaded into RAM when the channel is selected.

Once new data is loaded into the buffer, a single pulse from IC301 appears at IC401 to instruct the

synthesizer controller to latch and execute the new data. IC401 utilizes internal circuitry to determine

whether the present VCO output frequency is correct by comparing the phase and frequency of the VCO

signal at Pin 11 to the 14.4 MHz reference oscillator at Pin 20. IC401 produces an output signal at Pin 6,

a single-ended phase/frequency detector output, proportional to the phase difference between the two

input signals.

The loop filter C429, C427, R419, R420, R418, and C426 transform the Pin 6 output signal to a DC

voltage for application to the VCO tuning varactor CR402. The synthesizer system is “locked” when the

phase and frequency of both the reference and the divided VCO signal are the same.

The maximum amount of current this output can sink or source is determined by the value of R421 tied to

Pin 8 of IC401, with the output current programmable to 25, 50 or 100% of maximum.

SST-444 THEORY OF OPERATION

VCO / Buffer Amplifiers

Q403, L401, CR402 and associated components form the VCO (Voltage Controlled Oscillator), a resonant

circuit that oscillates at frequencies from 416 MHz in receive (receive frequency - 43.65 MHz) to 470 MHz

in transmit. Varying the voltage at CR402 changes the varactor capacitance, which in turn alters the VCO

output frequency. When in transmit mode a +5 VDC T/RSW signal is applied to Q406, which turns on

Q405 to draw current through pin diode CR404 and L403. With CR404 biased on, L402 is effectively

shorted to ground, shifting the VCO frequency up 43.65 MHz. Q401 and Q402 are buffer amplifiers, with

Q401 feeding in the input of the synthesizer at Pin 11, the receiver 1st local oscillator and the transmitter

pre-amplifier.

Oscillator Modulation

When the SST-444 is in transmit, modulation balance control IC306E passes TX audio through to the

VCO modulation input at R416. TX audio is applied to varactor CR403 to modulate the VCO. TX audio is

also routed to the Pin 1 input of TCVCXO reference oscillator Y302. Low frequency tones modulate the

reference oscillator because the synthesizer is not able to track them.

DIGITAL POTENTIOMETERS

IC306 contains 6 digital potentiometers programmed by IC301, sharing the same clock and data outputs

used by the synthesizer and a separate Digital Pot Latch signal from Pin 8. The digital potentiometers are

used in conjunction with IC303B, a summing node amplifier used for modulating the VCO and reference

oscillator. IC306A, B, D, E, and F can only be changed through serial programming, and can only be

performed by an authorized licensed RF technician.

IC306A is connected through R352 to the Pin 6 input of IC303B. IC306A adjusts the DC output of IC303B

to tune the reference oscillator frequency.

IC306B is connected to the Pin 2 Gate control of RF power transistor Q203 to adjust transmitter power

output.

Volume control IC306C applies the processed voice band signals at IC303D to audio amplifier IC307

when in receive mode. Depressing the ON/VOL UP switch SW301 increases the setting of IC306C while

VOL DN/OFF switch SW302 decreases it.

Transmitter tone deviation control IC306D applies the output of the selective signaling low-pass filter

IC308 to the Pin 6 input of IC303B through R350. IC306D is completely closed in receive mode.

Transmitter modulation balance control IC306E is used to apply the Pin 7 output of IC303B to the VCO

modulation input. This will set the ratio of the modulating signal applied to the VCO and the reference

oscillator. IC306E is completely closed in receive mode.

Transmitter voice deviation control IC306F applies the processed voice band signals at IC303D to the Pin

6 input of IC303B through R349. IC306F is completely closed in receive mode.

SST-444 THEORY OF OPERATION

RECEIVER

As mentioned before, Q101 switches the regulated +5 VDC to the receiver. The +VRX receiver voltage is

switched at the strobe duty cycle if programmed for power strobe.

RF Amplifier

A received signal from the antenna passes through a low-pass filter (L207, C216, C217, L206, C101, and

C202) to the receiver headend. L101 and the associated capacitors form a bandpass filter ahead of low-

noise RF amplifier Q102. L101 and C103 provide a notch at the image frequency, 87.3 MHz below the

receive frequency. The amplified RF signal is applied to a 2-pole bandpass filter consisting of L103, L104,

and associated capacitors. This circuit can be tuned for any 10 MHz band between 450 and 470 MHz.

1st Mixer

The amplified received input signal is applied to the gate of FET mixer Q103. The 1st local oscillator

signal from the synthesizer module is applied to the source of Q103. L106, C117 and C118 tune the drain

output of Q103 to 43.65 MHz and apply it to YF101, a 43.65 MHz two-pole crystal filter. Q104 and

associated components amplify the 43.65 MHz IF signal and apply it to the input of the 2nd mixer at Pin 16

of IC101.

FM Receiver Subsystem

A multi-function integrated circuit, IC101 and associated components for the FM-receiver subsystem. The

subsystem performs the following functions: 1) 2nd mixer, 2) 2nd IF amplifier, 3) FM detector, and 4)

noise amplifier.

The Pin 4 output of 14.4 MHz reference oscillator Y302 is multiplied up to 43.2 MHz by Q105 and

associated components. This signal is applied to the 2nd local oscillator input at Pin 1 of IC101. The

43.65 MHz signal at Pin 16 and the 2nd local oscillator are mixed, with the resulting 450 KHz output signal

appearing at Pin 3. This signal is filtered by a 450 KHz 6-pole ceramic filter YF102 and applied to the

input of the limiting IF amplifier at Pin 5. IC101 Pin 6 is the de-coupled input to the IF amplifier, Pin 7 the

limited IF output signal. An internal quadrature detector, whose center frequency is determined by 450

KHz quadrature coil T101, detects the FM IF signal. One input of the quadrature detector is connected

internally to the IF signal at Pin 7, while the other input is the phase-shifted signal from T101 at Pin 8.

Demodulated audio appears at Pin 9, where a low-pass filter (R114, C130) removes spurious quadrature

output prior to application to the voice/tone conditioning audio circuitry. Demodulated audio from Pin 9 is

applied to the Pin 10 input of a noise filter/amplifier consisting of R112, C123, C124, R110, R111 and

R113. The Pin 11 output of the noise amplifier is applied to a biased noise detector CR103, with the

output connected to an A/D input of IC301 at Pin 19. The SST-444 is serial programmed to set the

squelch threshold and hysteresis.

Voice / Tone Conditioning in Receive Mode

SST-444 audio conditioning filter circuits are shared with the transmitter. The same high-pass

filter/amplifier (IC303C and associated components) used in receive voice band conditioning is used in the

transmit band. Similarly, the low-pass filter (IC308 and associated components) used for selective signal

tone decode filtering is also used for selective signal encoding. Altering circuit configuration with bilateral

switches IC304A, B and C permits the use of the same audio filtering system for both transmit and receive

modes.

After R114 and C130 remove the 450 KHz element from the demodulated audio output at Pin 9 of IC101,

C333 couples the audio signal to bilateral switch IC304C for subaudible tone detection and connection to

IC304A for voice band audio processing.

SST-444 THEORY OF OPERATION

Voice Band

Bilateral switch IC304A passes the received audio signal to the input of IC303C, which along with its

associated components for a high-pass filter/amplifier circuit that attenuates audio signals below 300 Hz.

The output of IC303C is applied to the input of IC305B limiting amplifier. Bilateral switch IC304B is

switched in receive to insert C351 into the feedback circuit of IC305B, providing de-emphasis of the

received audio signal. Bilateral switch IC304B also removes R335 from the Pin 6 input to reduce the gain

and prevent limiting. The output from IC305B is applied to the input of IC303D, which along with its

associated components form an 18dB/octave low-pass filter for frequencies above 3000 Hz. The output

of IC303D is connected to IC306C volume control prior to connection to audio amplifier IC307. The output

of IC303D is also connected to IC306F voice deviation control, which is completely closed in receive mode

to prevent received signals from modulating the VCO and reference oscillators.

Audio frequency tones from Pin 23 of microcontroller IC301 are applied to the Pin 6 input of IC305B to

provide the SST-444 alert tones.

Sub-Audible

Bilateral switch IC304C passes the received audio signal to the input of IC305A, which amplifies the signal

and applies it to the Pin 2 input of IC308, a 5-pole low-pass filter that attenuates frequencies above 250

Hz. The output at Pin 5 is applied to an A/D input of IC301 at Pin 18 for tone decoding. An internal digital

signal processing routine programmed into microcontroller IC301 is used to decode the correct selective

signaling code. The output at Pin 5 of IC308 is also connected to tone deviation control IC306D, which is

completely closed in receive mode to prevent received subaudible tone signals from modulating the VCO

and reference oscillators.

Audio Amplifier

Receive audio from volume control IC306C is applied to the Pin 2 input IC307, a 1 Watt audio amplifier.

C365 couples the Pin 5 output to the internal 8Ω speaker SP301 via audio jack J303.

Microcontroller IC301 Pin 22 switches DC power to the audio amplifier by turning on Q07, which then turns

on pass transistor Q308 to apply battery voltage to Pin 6 of the audio amp. CR307 prevents an

inadvertent DC voltage at J303 from damaging the audio amplifier.

ANTENNA SWITCHING / LOW PASS FILTER

A low-pass filter comprised of filter L203, C213, C214, L204, C217, L207, and C216 removes harmonics

from the transmitter output before applying the RF signal to the antenna. Received signals pass through

the low-pass filter before entering the receiver RF amplifier circuitry.

Two PIN diodes (CR201, CR101) and associated components form the antenna switching circuit. With

the SST-444 in receive mode, no voltage is applied to the PIN diodes and they do not conduct. This

reverse biases CR201 to prevent the transmitter amplifier from affecting the receiver tuning and removes

CR101 from the receiver input. Incoming signals from the antenna pass through the low-pass filter, then

L206 and C102 to the receiver headend.

When the SST-444 is switched into transmit mode, transmitter supply voltage is switched on by Q201 and

Q202 and applied to R207. Current flows through R207, L205, CR201, L206 and then CR101 to ground,

forward biasing the PIN diodes. CR201 passes transmitter RF power to the antenna while CR101 shunts

the receiver RF amplifier input to ground. L206 provides sufficient impedance to isolate the transmitter

power from the receiver RF amplifier.

SST-444 THEORY OF OPERATION

TRANSMITTER

Keying

The SST-444 transmitter is keyed when PTT switch SW304 is depressed. Electret condenser

microphone M301 is connected in series to ground with the PTT switch, which when depressed draws

current through M301, SW304, CR304 and R307 to turn on pass transistor Q302. Q302 then turns on

Q301 to pull the TX Key Pin 2 input of microcontroller IC301 low. The microcontroller T/R output at Pin 11

then goes high to turn on Q202, which turns on pass transistor Q201 to apply +6VDC to the transmitter as

described previously. The transmitter can also be keyed through J301 with an audio accessory that

inserts a microphone and PTT switch in series to ground, drawing current through CR304.

+VTX Supply

With the transmitter enabled as described above, the +VTX voltage from Q201 is applied to transmitter

RF amplifier Q204. +VTX supply also forward biases the PIN switching diodes CR201 and CR101 as

previously described. The transmitter RF final amplifier Q203 is powered by the battery supply.

The Pin 11 T/R output of microcontroller IC301 can be PC programmed to hold the transmitter on after the

PTT switch has been released to allow tone related turn-off codes for squelch tail elimination.

Power Amplifier

Q204 and associated components amplify the VCO signal and apply it to the input of RF Final amplifier

module Q203 at Pin 1. The 50Ω output of Q203 is matched to the antenna switching circuitry and applied

to the antenna through the low-pass filter.

The RF power output is programmable by a licensed RF technician. The SST-444 can be programmed

on a channel-by-channel basis for low or high power operation. The power control digital Potentiometer

IC306B is used to adjust the Q203 gate voltage and set RF power output.

Voice / Tone Conditioning in Transmit Mode

SST-444 audio conditioning filter circuits are shared with the receiver. The same high-pass filter/amplifier

(IC303C and associated components) used in receive voice band conditioning is used in the transmitter

voice band. Similarly, the low-pass filter (IC308 and associated components) used for sub-audible tone

decode filtering is also used for tone encode. Altering circuit configuration with bilateral switches IC304A,

B and C permits the use of the same audio filtering system for both transmit and receive modes.

Voice Band

M301 microphone audio is passes through CR304, C334 and is switched by IC304A to the input of

IC303C, which along with its associated components form a high-pass filter/amplifier circuit that

attenuates audio signals below 300 Hz. The output of IC303C is applied to the input of IC305B limiting

amplifier. Bilateral switch IC304B switches R335 in parallel with R336, raising the gain of limiting amplifier

IC305B for full limiting of the transmitter voice audio. The output of IC305B is applied to the input of

IC303D, which along with its associated components form an 18 dB/octave low-pass filter for frequencies

above 3 KHz. The output of IC303D is applied to voice deviation control IC306F, which sets the level of

the processed transmitter audio applied to summing node amplifier IC303B used to modulate the VCO

and reference oscillator.

SST-444 THEORY OF OPERATION

Sub-Audible

Microcontroller IC301 generates the sub-audible selective signaling encode waveforms at Pin 21 and

applies them to the input of buffer amplifier IC305A. The output of IC305A is applied to the input of IC308,

a 5-pole low-pass filter that attenuates frequencies above 250 Hz. C342 and C343 set the corner

frequency of the low-pass filter, with C342 switched in by Pin 7 of IC301 to lower the corner frequency for

lower tones. The output of IC308 is applied to tone deviation control IC306D, which sets the level of the

transmitter sub-audible encode tones applied to summing node amplifier IC303B used to modulate the

VCO and reference oscillator.

MICROCONTROLLER

The SST-444 handheld transceiver is electronically controlled by IC301, an 8-bit microcontroller. IC301

has four 8-bit A/D inputs for processing analog signals.

PIN DESCRIPTION

1 RESET is connected to the SST-444 +5V to start the radio in a known state on power up.

2 TX KEY input is pulled LOW when either the internal or external PTT switch is pressed to initiate

transmitter operation.

3 AUDIO GATE ENABLE controls analog switches IC304A, B and C to configure the shared audio

processing circuitry for receive operation when LOW, and for transmitter operation when HIGH.

4, 25 SERIAL DATA INPUT links the microcontroller to communications from an external data terminal

via J303 RING connection. This allows programming of the SST-444 EEPROM memory used to

store channel frequency and configuration information.

5 DATA output sends serial data to frequency synthesizer IC401 to program frequency information,

IC302 EEPROM memory, and to IC306 to set the digital potentiometers.

6 EECLOCK output sends serial data clock pulses to EEPROM IC302 when reading or writing.

7 LOW-PASS CUT-OFF output goes LOW to lower the cut-off frequency of IC308 when the radio is

on a channel programmed for a CTCSS tone below 150 Hz. This output is in a tri-state OPEN

condition for all other tones.

8 DIGITAL POT LATCH sends a single positive pulse after data has been sent to IC306 to latch the

new data and change the digital potentiometers to the new programmed settings.

9 LED output goes LOW when the radio is on channel 1 and is HIGH for all other channels.

10 +5V SW output goes HIGH at a programmable periodic rate to remove the +5VSW supply from

various circuits in the radio, thus conserving battery life. In normal transmit or receive mode this

output is LOW.

11 T/R SWITCH output is connected to the Synthesizer circuitry to shift the frequency of the VCO

oscillator used in both transmit and receive. The output is HIGH in transmit and LOW in receive.

T/R output is also used to switch supply voltage to the transmit and receive circuits.

12 CLOCK output sends serial data clock pulses to frequency synthesizer IC401 and digital

potentiometers IC306 when programming these devices.

SST-444 THEORY OF OPERATION

PIN DESCRIPTION

13 +V SW output is HIGH when the radio is turned on, keeping pass transistor Q304 turned on via

Q303 to supply power to the radio.

14 GROUND

15 VREFH sets the upper reference level for the A/D and is connected to the regulated +5 VDC.

16 A/D input BATTERY is used to measure the battery voltage for low and dead battery detection.

This input also serves as the ON/VOL UP input, and is pulled LOW when SW301 is depressed to

turn on the radio and raise the receiver speaker audio level.

17 A/D input VOL DN/OFF is pulled LOW when SW302 is depressed to lower the receiver speaker

audio level and turn off the radio. This input also serves as CHANNEL input, and goes to 2.5

VDC when channel selector switch SW303 is pressed to change the radio to the next

programmed channel.

18 A/D input TONE DECODE accepts the received QC (CTCSS) and DQC (DCS) waveforms after

signal processing for decode analysis.

19 A/D input RSSI is used to measure the output voltage of the noise detector for squelch detection.

20 LATCH output goes LOW to allow serial data to frequency synthesizer IC401 and goes HIGH to

latch the data, allowing the synthesizer to execute the new frequency information.

21 TONE ENCODE outputs generate the QC (CTCSS) and DQC (DCS) encode waveforms for

signal processing prior to modulating the VCO in transmit mode.

22 AUDIO AMP ENABLE output goes HIGH to apply power to audio amp IC307 for receiver speaker

audio or radio alert tones.

23 BEEP output generate the radio alert tones heard in the speaker.

24, 26 UNUSED

27 REFERENCE OSCILLATOR INPUT has the 3.6 MHz reference signal from the synthesizer.

28 +5 VDC VDD supply voltage.

SST-444 ALIGNMENT PROCEDURE

An authorized RF service technician must perform test and alignment of the SST-444. Do not attempt

service of the SST-444 if not completely familiar with the operation of frequency synthesized radio

operation. The SST-444 can operate in either Narrow Band (2.5 KHz deviation) or Wide Band (5 KHz

deviation) systems.

RECOMMENDED TEST EQUIPMENT

1) 0 to +15 VDC, 2A current-limited power supply 3) Oscilloscope (to 20 MHz)

2) RF Communications Test Set (to 470 MHz) with: 4) VTVM or DMM

- FM Deviation Meter

- RF Wattmeter 5) RITRON PC Programming Kit

- Frequency Counter (to 470 MHz)

- SINAD Measuring Device 6) RITRON SST-SRVBD Test Module

RADIO PREPARATION

1) Make sure the radio battery is fully charged.

2) Install the RITRON SST-SRVBD test assembly and serial programming cable as follows:

a) Remove the SST-444 antenna from the radio.

b) Plug the SST-SRVBD into the 2.5 mm and 3.5 mm jacks on top of the radio.

c) Screw the SST-SRVBD antenna nut fully into the SST-444 antenna connector.

d) Set the jumper on the SST-SRVBD assembly to the “UHF” position.

e) Connect the serial programming cable from the PC computer (with the RITRON PC programming

kit software installed) to the SST-SRVBD test assembly

3) Connect the FM communications test set to the BNC connector on the SST-SRVBD test assembly.

4) Turn on the radio to place it in operating mode.

5) From the PC Programmer on-screen menu, select “Tune Radio” to display the Alignment screen.

6) Set the RF Communications Test set to the Alignment Frequency indicated on the Alignment screen.

7) Press the appropriate “Select” button on the Alignment screen to make the following adjustments:

SELECT Alignment

Frequency Transmit frequency

Mod Bal Modulation balance

Tone QC/DQC tone encode deviation – wide band

QC/DQC tone encode deviation – narrow band

Voice Voice deviation with no tone – wide band

Voice deviation with no tone – narrow band

Voice deviation with tone – wide band

Voice deviation with tone – narrow band

Power Low transmitter power

High transmitter power

8) After you have completed alignment of the SST-444, turn the radio off. This will remove the test

frequencies and return to operation on the customer’s programmed frequencies.

SST-444 ALIGNMENT PROCEDURE

REFERENCE FREQUENCY

1) Make sure that the unit has been switched on and is at room temperature (approximately +25° C)

2) Select “Frequency” from the PC Programmer “Alignment” screen.

3) Set the RF communications test set to the Alignment Frequency on the Alignment screen.

4) Press the “Tune” button on the Alignment screen to activate the transmitter.

5) Transmitter frequency error should be less than +/- 500 Hz.

6) If frequency adjustment is required, press the left arrow on the tuning bar to lower the frequency or the

right arrow to raise the frequency.

7) Press the “Save” button to store the new alignment setting or “Cancel” to leave setting unchanged.

MODULATION BALANCE

Transmitter modulation balance has been set at the factory and should not require adjustment.

1) Select “Mod Bal” from the PC Programmer “Alignment” screen.

2) Set the RF communications test set to the Alignment Frequency on the Alignment screen.

3) Press the “Tune” button on the Alignment screen to activate the transmitter.

4) Check the de-modulated waveform for a 20 Hz square wave.

5) If adjustment of the modulation balance is required, press the left arrow on the tuning bar to flatten the

top of the waveform or the right arrow to reduce overshoot.

6) Press the “Save” button to store the new alignment setting or “Cancel” to leave setting unchanged.

TRANSMITTER TONE DEVIATION

Transmitter tone deviation has been set at the factory and should not require adjustment.

1) Select “Tone” from the PC Programmer “Alignment” screen.

2) Set the RF communications test set to the transmit frequency on the screen.

3) Select either “Wide Band” or “Narrow Band” by pressing the desired option button.

4) Press the “Tune” button on the Alignment screen to activate the transmitter.

5) If adjustment of the tone deviation is required, press the left arrow on the tuning bar to lower deviation

or the right arrow to raise deviation.

6) Press the “Save” button to store the new alignment setting or “Cancel” to leave setting unchanged.

SST-444 ALIGNMENT PROCEDURE

TRANSMITTER VOICE DEVIATION

Transmitter voice deviation has been set at the factory and should not require adjustment.

1) Select “Voice” from the PC Programmer “Alignment” screen.

2) Set the RF communications test set to the transmit frequency on the screen.

3) Select “Voice Only - Wide Band“, “Voice Only - Narrow Band”, “Voice & Tone – Wide Band”, or “Voice

& Tone – Narrow Band” by pressing the desired option button.

4) Press the “Tune” button on the Alignment screen to activate the transmitter.

5) If adjustment of the voice deviation is required, press the left arrow on the tuning bar to lower deviation

or the right arrow to raise deviation.

6) Press the “Save” button to store the new alignment setting or “Cancel” to leave setting unchanged.

TRANSMITTER POWER

Transmitter power has been set at the factory and should not require adjustment.

1) Select “Power” from the PC Programmer “Alignment” screen.

2) Set the RF communications test set to the transmit frequency on the screen.

3) Select “Low Power” or “High Power” by pressing the desired option button.

4) Press the “Tune” button on the Alignment screen to activate the transmitter.

5) If adjustment of the transmitter power is required, press the left arrow on the tuning bar to lower power

or the right arrow to raise power.

6) Press the “Save” button to store the new alignment setting or “Cancel” to leave setting unchanged.

RECEIVER SENSITIVITY AND SQUELCH

The SST-444 receiver is factory tuned for a frequency range of 460 - 470 MHz. The SST-444 receiver is

configured from the factory for Wide Band operation, with a Narrow Band Model available as an option.

The SST-444 receiver bandwidth is configured on a per radio basis, it cannot be switched on a per

channel basis.

The receiver may be tuned to any 10 MHz frequency band between 450-470 MHz.

1) Program the radio to a receive frequency in the middle of the desired 10 MHz band.

2) Set the RF communications test set generator to a frequency exactly 87.3 MHz below the

programmed receive frequency at a RF level of approximately –40 dB. Modulate the RF signal with a

1 KHz tone at 3 KHz deviation for wide band, 1.5 KHz deviation for low band.

3) Connect an 8-Ohm speaker to the 3.5mm audio jack on the SST-SRVBD test assembly.

4) Adjust L101 for the minimum received signal at this image frequency.

SST-444 ALIGNMENT PROCEDURE

5) Set the RF Communications Test Set generator to the programmed receive frequency at a RF level of

–120 dB. Modulate the RF signal with a 1 KHz tone at 3 KHz deviation for wide band, 1.5 KHz

deviation for low band.

6) Adjust L103 and L104 for the best receiver SINAD as measured across the 8-Ohm speaker.

7) Check receiver sensitivity at the lowest and highest operating frequencies and make slight adjustment

to L103 and L104 to balance between the two, if necessary.

RECEIVER NOISE SQUELCH

The noise squelch sensitivity is set at the factory for a 12dB SINAD signal. Using the PC Programmer,

squelch sensitivity can be adjusted on a per channel basis by adjusting the “Squelch Tightener” number to

between 0-7. The higher number will require a stronger received signal to open squelch.

1) Select “Channel” from the PC Programmer “Edit” menu on the main screen.

2) Select the channel to be set and press “Edit” button.

3) Set the RF communications test set to the transmit frequency on the screen.

4) Enter a Squelch Tightener number between 0-7.

5) Press the “OK” button on the Channel Edit screen to return to the Channel List screen.

6) Select any other channels to be set.

7) Press the “OK” button on the Channel List screen to return to the Main screen.

8) Select “Program Radio” from the PC Programmer “Radio” menu to save all setting changes.

SYNTHESIZER

The synthesizer is preset at the factory for operation between 460 and 470 MHz. There is no manual

adjustment to center the control voltage, with all adjustment performed by the factory selection of fixed

capacitor C413. Do not attempt to adjust the synthesizer control unless a key component in the

synthesizer has been replaced. Key components do not include the Y302 reference frequency TCVCXO

or IC401 synthesizer IC. Synthesizer alignment errors cause poor operation at temperature extremes.

Should adjustment of the VCO control voltage be necessary, the radio must first be disassembled and

powered up at 7.5 VDC. The following procedure defines testing of the VCO control voltage:

1) Select the channel that has the lowest receive frequency.

2) Connect a VTVM, DVM or oscilloscope to Test Point 1 and measure the VCO control voltage. This

voltage should be no less than 1.5 VDC.

3) Select the channel that has the highest receive frequency and measure Test Point 1. The control

voltage should be no higher than 4.5 VDC.

4) a) If adjustment of the VCO control voltage is required, remove the synthesizer shield top.

b) Replace C413 with a capacitor value that allows VCO control voltages between 1.5 and 4.5 VDC

for the operating frequencies desired. Decreasing the value of C413 will raise the operating

frequency of the VCO while increasing the value will lower the VCO frequency.

c) Replace the top of the synthesizer shield.

SST-444 VOLTAGE CHART

Measurement Conditions

Supply voltage at 7.5 VDC, radio in operating mode, volume control at minimum, power strobe enabled,

transmitter set for full power.

IMPORTANT: Because the SST-444 portable is constructed with grounding sub-planes, use a system

ground in the same proximity as the circuit being measured. All readings indicated as GND are true

system ground.

KEY: All measurements are in VDC unless indicated otherwise.

NC = No connection

GND = Ground

* = Voltage is strobed in Power Saver mode

→= See note in right column

SST-444 VOLTAGES

DEVICE PIN Transmit Receive Standby DESCRIPTION

CR101 1 0.7 0.0 0.0 TX/RX switching

2NCNCNC

3 GND GND GND

CR102 1 GND GND GND Voltage clamp

2 GND GND GND

30.0 0.0 *

CR103 1 GND GND GND Noise detection

20.0 →*→ amplified receiver noise

30.0 < 0.5 *

CR201 1 1.4 0.0 0.0 TX/RX switching

2NCNCNC

3 0.7 0.0 0.0

CR301 C 7.5 7.5 7.5 Over voltage protection

A GND GND GND

CR302 C 7.5 7.5 7.5 Reverse voltage protection

A 2.2 4.8 4.8

CR303 1 6.8 6.8 6.8 Turn-on detection

2 4.2 4.2 4.2

3 6.1 6.1 6.1

CR304 1 2.0 4.7 4.7 PTT switching

2 2.2 4.7 4.7

3 2.4 5.0 5.0

CR305 1 GND GND GND Voltage clamp

2 5.0 5.0 5.0

3 0.0 0.0 0.0

CR306 1 2.4 2.4 2.4 Voltage clamp

2NCNCNC

3 2.4 2.4 2.4

CR307 C 7.5 7.5 7.5 Reverse voltage protection

A0.0 →*→ receive audio amp output

SOT-23

SST-444 VOLTAGE CHART

DEVICE PIN Transmit Receive Standby DESCRIPTION

CR401 1 5.0 5.0 * Biasing

24.8 4.8 *

3NCNCNC

CR402 1 GND GND GND VCO tuning

2NCNCNC

3→→ *→ 1.5 – 4.5 VDC VCO tuning voltage

CR403 1 GND GND GND VCO modulation

2NCNCNC

32.4 2.4 *

CR404 1 0.8 0.0 * TX/RX VCO switching

2NCNCNC

30.0 4.8 *

IC101 1 0.0 4.7 * RX FM-IF subsystem

2NCNCNC

30.0 3.8 *

40.0 4.7 *

50.0 3.8 *

60.0 3.8 *

70.0 3.8 *

80.0 4.7 *

90.0 2.0 *

10 0.0 0.6 *

11 0.0 2.4 *

12 0.0 0.0 *

13 NC NC NC

14 NC NC NC

15 GND GND GND

16 0.0 1.7 *

IC301 1 5.0 5.0 5.0 Microcontroller

2 0.0 5.0 5.0

3 5.0 0.0 0.0

4 0.0 0.0 0.0

5 0.0 0.0 0.0

6 0.0 0.0 0.0

7 0.0 0.0 0.0

8 0.0 0.0 0.0

9→→→→

0.0 VDC on Channel 1 else 5.0 VDC

10 0.0 0.0 *

11 5.0 0.0 0.0

12 5.0 5.0 *

13 5.0 5.0 5.0

14 GND GND GND

15 5.0 5.0 5.0

16 4.2 4.2 4.2

17 5.0 5.0 5.0

18 2.4 2.4 *

19 0.0 0.5 *

20 5.0 5.0 5.0

21 →2.4 * → 0-5 VDC tone encode waveform

22 0.0 5.0 0.0

23 0.0 0.0 0.0

24 NC NC NC

25 0.0 0.0 0.0

26 NC NC NC

27 →→→→

3.6 MHz clock signal

28 5.0 5.0 5.0

SST-444 VOLTAGE CHART

DEVICE PIN Transmit Receive Standby DESCRIPTION

IC302 1 GND GND GND EEPROM

2 GND GND GND

3 GND GND GND

4 GND GND GND

5 0.0 0.0 0.0

6 0.0 0.0 0.0

7 GND GND GND

8 5.0 5.0 5.0

IC303 1 2.4 2.4 * Audio processing

22.4 2.4 *

32.4 2.4 *

45.0 5.0 *

52.4 2.4 *

62.4 2.4 *

72.4 2.4 *

82.4 2.4 *

92.4 2.4 *

10 2.4 2.4 *

11 GND GND GND

12 2.4 2.4 *

13 2.4 2.4 *

14 2.4 2.4 *

IC304 1 0.0 0.0 * Audio signal switching

22.4 2.4 *

32.4 2.4 *

42.4 2.4 *

50.0 2.5 *

6 GND GND GND

7 GND GND GND

8 GND GND GND

9 5.0 0.0 0.0

10 5.0 0.0 0.0

11 5.0 0.0 0.0

12 2.4 2.4 *

13 NC NC NC

14 0.0 2.4 *

15 0.0 2.4 *

16 5.0 5.0 5.0

IC305 1 2.4 2.4 * Audio processing

22.4 2.4 *

32.4 2.4 *

4 GND GND GND

52.4 2.4 *

62.4 2.4 *

72.4 2.4 *

85.0 5.0 *

SST-444 VOLTAGE CHART

DEVICE PIN Transmit Receive Standby DESCRIPTION

IC306 1 2.0 2.0 * Audio signal level control

23.8 0.0 *

3 GND GND GND

40.0 2.5 *

52.4 2.4 *

62.4 2.4 *

72.4 2.4 *

80.0 0.0 *

95.0 5.0 *

10 GND GND GND

11 NC NC NC

12 0.0 0.0 *

13 2.4 2.4 *

14 2.4 2.4 *

15 2.4 2.4 *

16 2.4 2.4 *

17 2.4 2.4 *

18 4.0 4.0 *

19 5.0 5.0 *

20 5.0 5.0 *

IC307 1 NC NC NC Audio amplifier

2 0.0 0.0 0.0

3 GND GND GND

4 GND GND GND

5 0.0 3.7 0.0

6 0.0 7.5 0.0

7 0.0 3.7 0.0

8 NC NC NC

IC308 1 2.4 2.4 * Tone low pass filter

22.4 2.4 *

3 GND GND GND

45.0 5.0 *

52.4 2.4 *

62.4 2.4 *

75.0 5.0 *

83.2 3.2 *

IC309 1 7.5 7.5 7.5 +5 VDC voltage regulator

2 GND GND GND

3 7.5 7.5 7.5

4NCNCNC

5 5.0 5.0 5.0

SST-444 VOLTAGE CHART

DEVICE PIN Transmit Receive Standby DESCRIPTION

IC401 1 →→→→

3.6 MHz clock signal

2 5.0 5.0 * Frequency synthesizer

3NCNCNC

4NCNCNC

5 5.0 5.0 5.0

6→→ *→ 1.5 – 4.5 VDC VCO tuning voltage

7 GND GND GND

82.2 2.2 *

9NCNCNC

10 2.4 2.4 *

11 2.4 2.4 *

12 5.0 5.0 *

13 NC NC NC

14 5.0 5.0 5.0

15 0.0 0.0 *

16 NC NC NC

17 5.0 5.0 5.0

18 5.0 5.0 *

19 0.0 0.0 *

20 2.2 →2.2 →*→ 14.4 MHz reference signal

Q 101 1 5.0 4.3 * RX +V switching

25.0 5.0 *

30.0 4.7 *

Q 102 1 0.0 0.7 * RX RF amplifier

2 GND GND GND

30.0 3.0 *

Q 103 1 0.0 4.7 * RX mixer

20.0 0.0 *

30.0 1.8 *

Q 104 1 0.0 0.7 * RX IF amplifier

2 GND GND GND

30.0 1.2 *

Q 105 1 0.0 0.7 * RX 2nd LO multiplier/amp

2 GND GND GND

30.0 4.6 *

Q 201 1 6.8 7.5 7.5 TX +V switching

2 7.5 7.5 7.5

3 6.0 0.0 0.0

Q 202 1 5.0 0.0 0.0 TX +V switching

2 4.3 0.0 0.0

3 6.8 7.5 7.5

Q 203 1 0.0 0.0 0.0 TX RF final amplifier

2 3.8 0.0 0.0

3 7.5 7.5 7.5

4 0.0 0.0 0.0

5 GND GND GND

Q 204 1 0.9 0.0 0.0 TX RF driver amplifier

2 0.3 0.0 0.0

3 6.0 0.0 0.0

SST-444 VOLTAGE CHART

DEVICE PIN Transmit Receive Standby DESCRIPTION

Q 301 1 5.0 0.0 0.0 PTT detection

2 GND GND GND

3 0.0 5.0 5.0

Q 302 1 4.3 5.0 5.0 PTT detection

2 5.0 5.0 5.0

3 5.0 0.0 0.0

Q 303 1 5.0 5.0 5.0 Battery +V switching

2 4.3 4.3 4.3

3 6.8 6.8 6.8

Q 304 1 6.8 6.8 6.8 Battery +V switching

2 7.5 7.5 7.5

3 7.5 7.5 7.5

Q 306 1 4.3 4.3 5.0 +5V switching

2 5.0 5.0 5.0

35.0 5.0 *

Q 307 1 0.0 5.0 0.0 Audio amplifier enable

2 0.0 4.3 0.0

3 7.5 6.8 7.5

Q 308 1 7.5 6.8 7.5 Audio amplifier +V switching

2 7.5 7.5 7.5

3 0.0 7.5 0.0

Q 401 1 0.7 0.7 * VCO buffer amplifier

2 GND GND GND

32.9 2.9 *

Q 402 1 0.7 0.7 * VCO buffer amplifier

2 GND GND GND

32.8 2.8 *

Q 403 1 2.3 2.3 * VCO oscillator

21.6 1.6 *

34.3 4.3 *

Q 404 1 4.7 4.7 * VCO voltage de-coupling

24.3 4.3 *

35.0 5.0 *

Q 405 1 0.0 4.3 * TX/RX VCO switching

24.3 4.3 *

34.2 0.0 *

Q 406 1 0.0 4.3 * TX/RX VCO switching

2 GND GND GND

34.3 0.0 *

SST-444 SCHEMATIC REFERENCE PARTS LIST

NOTE: This parts list reflects the most current component values. If a component value given in the

schematic differs from this list, the parts list should be considered the most current.

Last Update: June 13, 2000

Ref Ritron PN Description X Y Theta Loc

CAPACITORS

C101 151103A3 3.3pf NPO 0805 CHIP CAPACITOR 1065 3824 270 Top

C102 151102A2 2.2PF NPO 0805 50V CHIP CAP 949 3929 180 Top

C103 15110120 12PF NPO 0805 50V CHIP CAP 791 4059 90 Top

C104 15110220 22PF NPO 0805 50V CHIP CAP 909 3824 270 Top

C105 15110180 18PF NPO 0805 50V CHIP 1018 3608 270 Top

C106 15110180 18PF NPO 0805 50V CHIP 869 3716 180 Top

C107 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 734 3620 180 Top

C108 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 675 3519 90 Top

C109 151106A8 6.8PF NPO 0805 50V CHIP 637 3994 90 Top

C110 151103A9 3.9PF NPO 0805 50V CHIP 557 3993 270 Top

C111 151103A3 3.3pf NPO 0805 CHIP CAPACITOR 516 4099 180 Top

C112 151103A3 3.3pf NPO 0805 CHIP CAPACITOR 382 4099 180 Top

C113 15110100 10PF NPO 0805 50V CHIP CAP 476 3993 270 Top

C114 151108A2 8.2PF NPO 0805 50V CHIP 275 4059 270 Top

C115 15110150 15PF 0805 NPO 50V CHIP CAP 380 3786 0 Top

C116 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 276 3382 180 Top

C117 15110150 15PF 0805 NPO 50V CHIP CAP 199 3598 180 Top

C118 15110470 47PF NPO 0805 50V CHIP 160 3491 90 Top

C119 15181472 .0047uF CAPACITOR, CHIP, 0402, X7R,5/10% 485 3367 270 Top

C120 151108A2 8.2PF NPO 0805 50V CHIP 407 3548 0 Bottom

C121 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 138 947 90 Bottom

C122 152B6106 10uF 10V 3.4 X 2.8 CHIP TANTALUM 451 1669 0 Bottom

C123 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 450 946 90 Bottom

C124 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 349 884 0 Bottom

C125 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 350 1364 0 Bottom

C126 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 441 1557 0 Bottom

C127 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 69 2203 0 Bottom

C128 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 225 2114 270 Bottom

C129 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 392 1802 0 Bottom

C130 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 571 904 90 Bottom

C131 15110330 33PF NPO 0805 50V CHIP 38 1263 0 Bottom

C132 15110330 33PF NPO 0805 50V CHIP 64 1156 270 Bottom

C133 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 69 2100 0 Bottom

C134 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 39 1635 90 Top

C135 15110220 22PF NPO 0805 50V CHIP CAP 171 1533 180 Bottom

C201 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1302 3153 90 Bottom

C202 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 871 3384 270 Bottom

C203 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 997 3248 90 Bottom

C204 152A8105 1MFD 16V ~3.2 X 1.6~ CHIP TANTALUM 1100 3496 270 Top

C205 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1019 3494 90 Top

C206 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1748 3308 90 Bottom

C207 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1748 3104 90 Bottom

C208 15110100 10PF NPO 0805 50V CHIP CAP 1796 2406 90 Top

C209 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 1427 2284 90 Bottom

C210 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1492 2264 90 Bottom

C211 15110560 56PF NPO 0805 50V CHIP CAPACITOR 1715 2211 270 Top

C212 15110101 100PF NPO 0805 50V CHIP CAP 1788 3787 90 Top

C213 151103A9 3.9PF NPO 0805 50V CHIP 1682 3828 180 Top

C214 15110100 10PF NPO 0805 50V CHIP CAP 1652 4093 90 Top

C215 FACTORY SELECT 1439 4093 90 Top

C216 15110101 100PF NPO 0805 50V CHIP CAP 953 4136 90 Top

C217 151105A6 5.6PF NPO 0805 50V CHIP CAPACITOR 1035 4136 90 Top

C301 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 774 817 180 Bottom

SST-444 SCHEMATIC REFERENCE PARTS LIST

Ref Ritron PN Description X Y Theta Loc

C302 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 275 522 270 Top

C303 152B4226 22uF 6.3V 3.4 X 2.8 CHIP TANTALUM CAP 199 647 180 Top

C304 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1261 4590 90 Bottom

C305 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1027 427 0 Top

C306 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 613 402 270 Top

C307 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 20 4621 270 Top

C308 15111102 .001MF X7R 0805 50V CHIP CAP 0 0 0 Bottom

C309 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 496 1867 90 Bottom

C310 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 1107 3264 0 Bottom

C311 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1229 2967 90 Bottom

C312 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 544 4622 270 Top

C313 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 169 3033 270 Top

C314 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1280 2568 180 Bottom

C315 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1280 2271 180 Bottom

C316 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 826 2291 180 Top

C317 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 704 2321 0 Bottom

C318 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 826 2371 180 Top

C319 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 704 2407 0 Bottom

C320 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1280 2410 180 Bottom

C321 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1280 2488 180 Bottom

C322 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1280 2311 180 Bottom

C323 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1280 2771 180 Bottom

C324 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 969 2221 0 Top

C325 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1280 2687 180 Bottom

C326 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1280 2607 180 Bottom

C327 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1280 2371 180 Bottom

C328 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 704 2446 0 Bottom

C329 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 638 2501 270 Bottom

C330 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 704 2571 0 Bottom

C331 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 704 2610 0 Bottom

C332 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 737 2672 270 Bottom

C333 152A6475 4.7UF 10V A-SIZE TANTALUM CHIP CAP 502 2703 180 Top

C334 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 95 2765 180 Bottom

C335 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 420 2842 270 Bottom

C336 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 454 3156 90 Bottom

C337 152B6106 10uF 10V 3.4 X 2.8 CHIP TANTALUM 724 3558 270 Bottom

C338 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 254 3129 90 Top

C339 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 245 2945 270 Top

C340 15111333 .033MFD X7R 0805 50V CHIP CAP 366 2665 270 Bottom

C341 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 585 2328 270 Bottom

C342 15110821 820PF NPO 0805 50V CHIP CAP 638 2964 180 Bottom

C343 15111122 .0012MF X7R 0805 50V CHIP 637 3045 180 Bottom

C344 15181472 .0047uF CAPACITOR, CHIP, 0402, X7R,5/10% 184 2436 0 Top

C345 15181472 .0047uF CAPACITOR, CHIP, 0402, X7R,5/10% 269 2436 0 Top

C346 152A8105 1MFD 16V ~3.2 X 1.6~ CHIP TANTALUM 614 2232 90 Top

C347 15180180 18pF CAPACITOR, CHIP, 0402, COG, 5% 286 2500 90 Top

C348 15119473 .047uF X7R 0805 25V CHIP CAPACITOR 474 2595 0 Top

C349 15111333 .033MFD X7R 0805 50V CHIP CAP 127 2621 90 Bottom

C350 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 493 3156 90 Bottom

C351 15181222 .0022uF CAPACITOR, CHIP, 0402, X7R,5/10% 19 2670 180 Top

C352 15180100 10pF CAPACITOR, CHIP, 0402, COG, 5% 436 3228 90 Top

C353 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 593 3133 180 Top

C354 15180221 220pF CAPACITOR, CHIP, 0402, COG, 5% 379 2436 90 Bottom

C355 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 301 2435 90 Bottom

C356 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 258 2393 90 Bottom

C357 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 153 2415 180 Top

C358 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 585 2498 90 Bottom

C359 15180100 10pF CAPACITOR, CHIP, 0402, COG, 5% 490 2589 90 Bottom

C360 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 470 2270 270 Top

C361 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 492 2074 0 Top

C362 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 981 752 270 Bottom

SST-444 SCHEMATIC REFERENCE PARTS LIST

Ref Ritron PN Description X Y Theta Loc

C363 152B6106 10uF 10V 3.4 X 2.8 CHIP TANTALUM 1231 427 0 Top

C364 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 1058 503 180 Bottom

C365 01503212 220MF 10V ELT CAPACITOR, 5mm HEIGHT 1491 5052 0.302 Top

C366 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 1482 659 90 Bottom

C367 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 1357 798 90 Bottom

C368 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 247 2708 270 Bottom

C369 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 664 2454 90 Top

C401 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1566 1966 270 Top

C402 151101A5 1.5PF NPO 0805 50V CHIP 1640 194 90 Top

C403 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1680 1828 90 Top

C404 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1066 1850 180 Top

C405 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1353 2013 180 Top

C406 151101A5 1.5PF NPO 0805 50V CHIP 1182 1785 270 Top

C407 151104A7 4.7PF 0805 50V CHIP CAP. 1463 1604 0 Top

C408 151104A7 4.7PF 0805 50V CHIP CAP. 1572 1634 270 Top

C409 15119104 .1uF X7R 0805 25V CERAMIC CHIP CAP 980 1766 90 Top

C410 151104A7 4.7PF 0805 50V CHIP CAP. 1355 158 270 Top

C411 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1262 130 270 Top

C412 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1047 1788 90 Top

C413 151101A8 1.8PF NPO 0805 50V CHIP 1462 1441 270 Top

C414 152B6106 10uF 10V 3.4 X 2.8 CHIP TANTALUM 722 1625 0 Top

C415 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 1535 969 270 Top

C416 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1731 1114 270 Top

C417 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1538 1356 90 Top

C418 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 677 1121 180 Top

C419 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 678 1201 180 Top

C420 15181102 .001uF CAPACITOR, CHIP, 0402, X7R, 5/10% 678 1240 180 Top

C421 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1053 1576 180 Top

C422 15110100 10PF NPO 0805 50V CHIP CAP 1119 1512 180 Top

C423 151101A0 1.0PF NPO 0805 50V CHIP 1256 1400 0 Top

C424 151108A2 8.2PF NPO 0805 50V CHIP 1187 1252 270 Top

C425 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1069 937 90 Top

C426 15111222 .0022uF X7R 0805 50V CHIP CAPACITOR 832 922 180 Top

C427 152AB334 .33MF 35V ~3.2X1.6~ CHIP TANTALUM 812 1015 0 Top

C428 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 855 1473 270 Top

C429 15111333 .033MFD X7R 0805 50V CHIP CAP 1029 1015 0 Top

C430 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 971 1460 270 Top

C431 15182103 .01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20 687 1393 180 Top

C432 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 766 1100 180 Top

C433 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 932 1460 90 Top

C434 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 1101 1264 0 Top

C435 15180101 100pF CAPACITOR, CHIP, 0402, COG, 5% 687 1355 180 Top

DIODES

CR101 48D100A2 MA4CP101A PIN DIODE, SOT-23 1178 3820 90 Top

CR102 48E1005G MMBD-352LT1 SCHOTTKY DIODE SOT23 908 3608 270 Top

CR103 48A1005C MMBD7000, DUAL DIODES IN SERIES, SOT-23 356 2147 0 Bottom

CR201 48D100A2 MA4CP101A PIN DIODE, SOT-23 1302 3991 0 Top

CR301 48B61012 1N4742A ZENER DIODE, 12V 1W DL-41 MELF 991 604 90 Top

CR302 48AA01SA DIODE, 1A, 50V, SMT, D0214AC CASE 1154 630 90 Top

CR303 48A1005B MMBD6100, DUAL DIODES, COM CATHODE, SOT2 363 431 90 Top

CR304 48A100A3 MMBD2835, DUAL DIODES, COM ANODE, SOT-23 65 4089 0 Top

CR305 48A1005C MMBD7000, DUAL DIODES IN SERIES, SOT-23 626 2802 0 Bottom

CR306 48A1005C MMBD7000, DUAL DIODES IN SERIES, SOT-23 449 2956 90 Bottom

CR307 48AA01SA DIODE, 1A, 50V, SMT, D0214AC CASE 1290 630 90 Top

CR401 48A1005C MMBD7000, DUAL DIODES IN SERIES, SOT-23 695 1808 90 Top

CR402 48C1004E MMBV-105G DIODE VVC, SOT-23 1147 1115 180 Top

CR403 48C1004G MMBV-2101L DIODE VVC SOT-23 1119 1400 180 Top

CR404 48A1004D MMBV3401 PIN/UHF DIODE SOT-23 1552 1239 270 Top

SST-444 SCHEMATIC REFERENCE PARTS LIST

Ref Ritron PN Description X Y Theta Loc

FUSE

F301 06000040 WIRE; #40AWG TINNED BUS (INCHES) 754 603 270 Bottom

INTEGRATED CIRCUITS

IC101 31030003 MC3371D SUBSYSTEM IC, SO-16 314 1158 270 Bottom

IC301 314G0301 MCU, 28 PIN, SOIC, SST/JMX 4-SERIES v01 992 2546 0 Bottom

IC302 31210005 EEPROM, 512X8, 24C04 989 2501 180 Top

IC303 310K0004 LMV324MT RAIL TO RAIL QUAD OP AMP 474 2442 180 Top

IC304 311K0003 SWITCH,ANALOG,TRIPLE SPDT,4053,TSSOP-16 241 2683 0 Top

IC305 310K0003 LMV358MM DUAL OP AMP, GP LV R/R TSSOP 404 3120 0 Top

IC306 310K0001 DS1806E 6 PROG POTS 10K OHM 20-PIN TSSOP 242 2185 0 Top

IC307 31010004 LM386MX-1 AUDIO AMP SO-8 1331 567 90 Bottom

IC308 310K0002 MAX7410 5TH ORDER SW CAP BUTTERWORTH LPF 407 2935 0 Top

IC309 310E0002 REGULATOR,LDO,LP2980,5V,W ENABLE,SOT-25 162 504 0 Top

IC401 313K0004 SYNTHESIZER TSSOP MC145192 891 1265 180 Top

JACKS

J301 02100001 2.5MM PC-MT JACK; ANT-CHGR 1178 4668 0 Top

J303 02100053 3.5MM STEREO JACK; PANEL MOUNT 1560 4646 0 Top

INDUCTORS

L101 01850201 1.5T SW COIL W/5MM SHIELD & ALUM CORE 721 4291 90 Top

L102 18110151 CHIP INDUCTOR .15uhy 629 3722 270 Top

L103 01850201 1.5T SW COIL W/5MM SHIELD & ALUM CORE 484 4291 270 Top

L104 01850201 1.5T SW COIL W/5MM SHIELD & ALUM CORE 204 4292 270 Top

L105 18433103 3T AIRCOIL, SMT, 8.0nH, .120 X .145 332 3901 180 Top

L106 18110102 CHIP INDUCTOR 1.0uhy 280 3474 0 Top

L107 18433101 1T AIRCOIL, SMT 2.5nH, .120 X .145 480 3492 180 Top

L108 18110681 CHIP INDUCTOR .68uhy 51 1648 180 Bottom

L201 18414104 4.5T AIRCOIL #24AWG .0625” ID RHH SMT 929 3459 270 Top

L202 18110150 INDUCTOR, CHIP, 15nH 1454 2281 180 Top

L203 18414104 4.5T AIRCOIL #24AWG .0625"ID RHH SMT 1695 3948 90 Top

L204 18414104 4.5T AIRCOIL #24AWG .0625"ID RHH SMT 1479 3945 180 Top

L205 18110102 CHIP INDUCTOR 1.0uhy 1230 3667 0 Top

L206 18414105 5.5T AIRCOIL #24AWG .0625"ID RHH SMT 1093 3979 90 Top

L207 18433102 2T AIRCOIL SMT 5.0nH .120 X .145 932 4343 0 Top

L401 18433209 9T AIRCOIL, SMT, 9.85 nH, .159 X .056 1376 1418 270 Top

L402 18414109 9.5T AIRCOIL #24AWG .0625"ID RHH SMT 1352 118 0 Top

L403 18110820 INDUCTOR, CHIP 82nH 1548 109 270 Top

L404 18110101 CHIP INDUCTOR 0.1uhy 1187 966 270 Top

L405 18110101 CHIP INDUCTOR 0.1uhy 753 1485 0 Top

MICROPHONE

M301 05500037 MICROPHONE; ELECTRET, MINIATURE 0 0 0 Bottom

CONNECTORS

P201 25500700 CONTACT, PCB MNT, ANTENNA,SST 896 4550 90 Top

P302 21310021 HEADER, 2 PIN SIDE ENTRY SHROUDED 754 737 0 Top

TRANSISTORS

Q101 4801002A MMBT3906 PNP, SOT23 675 3405 270 Top

Q102 482100V0 TRANSISTOR, NPN, UHF, SOT-23, PBR-941 734 3828 0 Top

Q103 4841006U MMBFJ309LT1, N-CHAN, RF, SOT23 340 3639 270 Top

Q104 4821003B MMBT918LT1 VHF SOT23 (3B) 270 3548 0 Bottom

SST-444 SCHEMATIC REFERENCE PARTS LIST

Ref Ritron PN Description X Y Theta Loc

Q105 4821003B MMBT918LT1 VHF SOT23 (3B) 38 1374 180 Bottom

Q201 4801002A MMBT3906 PNP, SOT23 908 3268 90 Bottom

Q202 4801001Q MMBT5088 NPN, SOT-23 766 3268 270 Bottom

Q203 04801503 M68710H 2W RF MODULE 450-470 MHz 6.0V 1819 2710 90 Top

Q204 482100V0 TRANSISTOR, NPN, UHF, SOT-23, PBR-941 1603 2274 270 Top

Q301 48010R02 MUN2211T1, NPN, INT 10K/10K BIAS, "8A", 1133 2987 90 Bottom

Q302 4801002A MMBT3906 PNP, SOT23 1094 3124 90 Bottom

Q303 4801001Q MMBT5088 NPN, SOT-23 583 519 0 Top

Q304 480100DH BCW68GLT1 .8AMP PNP SOT-23 445 668 0 Top

Q306 4801002A MMBT3906 PNP, SOT23 1222 2259 90 Top

Q307 4801001Q MMBT5088 NPN, SOT-23 964 615 0 Bottom

Q308 480100DH BCW68GLT1 .8AMP PNP SOT-23 1162 712 0 Bottom

Q401 482100V0 TRANSISTOR, NPN, UHF, SOT-23, PBR-941 1470 1919 270 Top

Q402 482100V0 TRANSISTOR, NPN, UHF, SOT-23, PBR-941 1289 1920 270 Top

Q403 482100V0 TRANSISTOR, NPN, UHF, SOT-23, PBR-941 1460 1714 270 Top

Q404 4801001Q MMBT5088 NPN, SOT-23 837 1766 270 Top

Q405 4801006A MUN2111T1, PNP, INT 10K/10K BIAS, SC-59 1634 1376 270 Top

Q406 48010R02 MUN2211T1, NPN, INT 10K/10K BIAS, "8A", 1691 1234 0 Top

RESISTORS

R101 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 579 3344 90 Top

R102 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 734 3581 180 Top

R103 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 774 3716 270 Top

R104 47180392 3.9K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 829 3810 270 Top

R105 47180561 560 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 714 3519 270 Top

R106 47180152 1.5K OHM RESISTOR, CHIP, 0402, 1/16W,5% 475 3610 270 Top

R107 47180152 1.5K OHM RESISTOR, CHIP, 0402, 1/16W,5% 388 3484 180 Bottom

R108 47180223 22K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 251 3450 180 Bottom

R109 47180101 100 OHM RESISTOR, CHIP, 0402,1/16W,5% 167 3450 180 Bottom

R110 47180154 150K OHM RESISTOR, CHIP, 0402, 1/16W,5% 411 946 270 Bottom

R111 47180122 1.2K OHM RESISTOR, CHIP, 0402, 1/16W,5% 529 904 270 Bottom

R112 47180224 220K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 349 966 180 Bottom

R113 47180123 12K OHM RESISTOR, CHIP, 0402, 1/16W,5% 489 946 90 Bottom

R114 47180152 1.5K OHM RESISTOR, CHIP, 0402, 1/16W,5% 551 966 0 Bottom

R115 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 161 2174 270 Bottom

R116 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 161 2089 90 Bottom

R117 47180393 39K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 117 1676 90 Top

R118 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 79 1533 90 Bottom

R119 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 59 1470 180 Bottom

R120 47180681 680 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 78 1635 90 Top

R201 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 790 3384 90 Bottom

R202 47180471 470 OHM RESISTOR, CHIP, 0402, 1/6W, 5% 669 3248 270 Bottom

R203 47180181 180 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 908 3151 90 Bottom

R204 47100270 27 OHM 0805 CHIP RESISTOR 1796 2211 270 Top

R205 47180822 8.2K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1555 2244 0 Bottom

R206 47180182 1.8K OHM RESISTOR, CHIP, 0402, 1/16W,5% 1618 2264 270 Bottom

R207 47180181 180 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1184 3549 270 Top

R208 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 879 4148 90 Top

R301 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 536 686 90 Top

R302 47100471 470 OHM 0805 CHIP RES. 475 479 270 Top

R303 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 325 546 90 Top

R304 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 623 639 270 Top

R305 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 402 547 270 Top

R306 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 535 1867 90 Bottom

R307 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 995 3143 90 Bottom

R308 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 1127 3328 180 Bottom

R309 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 1257 2891 270 Bottom

R310 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 704 2191 0 Bottom

R311 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 504 4622 270 Top

R312 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 704 2230 0 Bottom

SST-444 SCHEMATIC REFERENCE PARTS LIST

Ref Ritron PN Description X Y Theta Loc

R313 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 1184 2376 270 Top

R314 47180472 4.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1260 2375 270 Top

R315 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 738 2841 90 Bottom

R316 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 761 2557 90 Top

R317 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 800 2506 90 Top

R318 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 704 2521 180 Bottom

R319 47180471 470 OHM RESISTOR, CHIP, 0402, 1/6W, 5% 737 2756 270 Bottom

R320 47180471 470 OHM RESISTOR, CHIP, 0402, 1/6W, 5% 698 2879 270 Bottom

R321 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 636 2899 0 Bottom

R322 47180393 39K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 294 3070 270 Bottom

R323 47180823 82K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 371 3070 270 Bottom

R324 47180224 220K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 332 3070 270 Bottom

R325 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 416 3156 90 Bottom

R326 47180183 18K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 585 2413 270 Bottom

R327 47180183 18K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 624 2328 90 Bottom

R328 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 493 2774 270 Bottom

R329 47180153 15K OHM RESISTOR, CHIP, 0402, 1/16W,5% 168 2374 90 Top

R330 47180100 10 OHM RESISTOR, CHIP,0402, 1/16W 5% 664 2369 90 Top

R331 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 269 2396 0 Top

R332 47180154 150K OHM RESISTOR, CHIP, 0402, 1/16W,5% 207 2501 90 Top

R333 47180473 47K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 246 2500 90 Top

R334 47180273 27K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 566 2588 90 Top

R335 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 60 2787 270 Top

R336 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 23 2787 270 Top

R337 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 532 3156 270 Bottom

R338 47180224 220K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 397 3228 90 Top

R339 47180394 390K OHM RESISTOR, CHIP, 0402, 1/6W, 5% 420 2347 270 Bottom

R340 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 340 2436 90 Bottom

R341 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 239 2455 0 Bottom

R342 47180184 180K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 153 2376 180 Bottom

R343 47180473 47K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 731 3133 0 Bottom

R344 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 67 2416 180 Bottom

R345 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 153 2455 180 Bottom

R346 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 732 3094 180 Top

R347 47180274 270K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 568 2588 90 Bottom

R348 47180473 47K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 529 2589 90 Bottom

R349 47180823 82K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 29 2146 0 Top

R350 47180564 560K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 29 2198 0 Top

R351 47180222 2.2K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 431 2269 90 Top

R352 47100475 4.7M OHM 0805 CHIP RESISTOR 44 2406 0 Top

R353 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 453 2158 180 Top

R354 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 847 653 180 Bottom

R355 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 912 772 90 Bottom

R356 47180273 27K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1293 780 90 Bottom

R357 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 1147 534 90 Bottom

R358 47180153 15K OHM RESISTOR, CHIP, 0402, 1/16W,5% 1187 534 90 Bottom

R359 47180100 10 OHM RESISTOR, CHIP,0402, 1/16W 5% 1482 773 270 Bottom

R401 47180221 220 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1517 2006 90 Top

R402 47180101 100 OHM RESISTOR, CHIP, 0402,1/16W,5% 1640 1828 270 Top

R403 47180272 2.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1450 2013 180 Top

R404 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 1452 1825 180 Top

R405 47180101 100 OHM RESISTOR, CHIP, 0402,1/16W,5% 1153 1900 270 Top

R406 47180272 2.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1193 1900 270 Top

R407 47180470 47 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1086 1788 270 Top

R408 47180470 47 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1067 1726 180 Top

R409 47180271 270 OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1636 1655 90 Top

R410 47180153 15K OHM RESISTOR, CHIP, 0402, 1/16W,5% 1266 162 5180 Top

R411 47180153 15K OHM RESISTOR, CHIP, 0402, 1/16W,5% 1363 1694 270 Top

R412 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 1271 1827 180 Top

R413 47180472 4.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 677 1903 0 Top

R414 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 1634 1531 270 Top

SST-444 SCHEMATIC REFERENCE PARTS LIST

Ref Ritron PN Description X Y Theta Loc

R415 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 1641 1068 90 Top

R416 47180104 100K OHM, RESISTOR, CHIP, 0402,1/16W,5% 1138 1576 0 Top

R417 47180102 1K OHM RESISTOR, CHIP,0402, 1/16W,5% 938 937 90 Top

R418 47180473 47K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 938 1022 90 Top

R419 47180822 8.2K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 718 906 0 Top

R420 47180103 10K OHM, RESISTOR, CHIP, 0402,1/16W,5% 718 946 180 Top

R421 47180223 22K OHM RESISTOR, CHIP, 0402, 1/16W, 5% 1101 1303 0 Top

R422 47180100 10 OHM RESISTOR, CHIP,0402, 1/16W 5% 894 1461 90 Top

R423 47180474 470K OHM RESISTOR, 0402, 1/16W, 5% 850 1100 180 Top

SPEAKER

SP301 05500045 SPEAKER, 45MM, 1W, LOW PROFILE SST/RTX 0 0 0 Bottom

SWITCHES

SW301 05100042 SWITCH SPST MOMENTARY MINI PC 260GM 268 4587 180 Top

SW302 05100042 SWITCH SPST MOMENTARY MINI PC 260GM 788 4588 180 Top

SW303 05100046 SWITCH, TACT LO PROFILE RT ANGLE 160gf 82 3097 270 Top

SW304 05100046 SWITCH, TACT LO PROFILE RT ANGLE 160gf 82 3948 270 Top

TRANSFORMER

T101 05600018 455KHZ IF TRANSFORMER (5MM) 128 1822 180 Top

CRYSTAL

Y302 23050003 TCVCXO, 14.400 MHz, 1.5 PPM, VC=30 PPM/V 146 837 90 Top

FILTERS

YF101 02301403 43.650 MHz Crystal Filter +/-6.0KHz UM-1 44 3524 90 Top

YF102 02301013 FILTER,CERAMIC,450KHz,+/-7.5KHz,6 POLE 249 1614 90 Top

HARDWARE

1750240B PCB, ML4 FR4 5UPM, .062 MIX, SST-444

25602500 CRYSTAL SUPPORT, RUBBER PAD, SMALL/UM-1

06001021 #28 AWG STRANDED WIRE; RED (INCHES)

06001023 #28 AWG STRANDED WIRE;GREEN INCHES

06001026 #28 AWG STRANDED WIRE; BLACK INCHES

06001029 #28 AWG STRANDED WIRE; BLUE INCHES

25105500 SHIELD, SST-PLUS SYNTHESIZER

25603000 FOAM, MOUNTING, SPEAKER,SST

25603900 SPACER, MIC FOAM, SST

25605700 MICROPHONE HOLDER, SST-PLUS

25900700 ADHESIVE, MTG, MIC HOLDER

26200800 HEATSINK, TOP, SST+

26200900 HEATSINK, BOTTOM, SST+

2811H401 SCREW #4-40 X .25 LG TRIM HEAD PHILLIPS

SST-444 CASE ASSEMBLY PARTS LIST

Ref Ritron PN Description

MAIN CASE ASSEMBLY

13250000 CASE W/INSERT, PLASTIC, SST BLACK

13578000 DOOR, BATTERY, PLASTIC, SST 2-PC

13588000 LATCH, BATTERY DOOR, PLASTIC SST 2-PC

25106400 BATTERY DOOR HINGE RETAINER

25201500 RETAINER, PLASTIC, PTT, SST

25400600 BUSHING, THREADED, PLATED, ANTENNA SS

25603300 GRILLE CLOTH, SPEAKER, SST

25603400 DUAL JACK PLUG, RUBBER,SST

25606200 HINGE, BATTERY DOOR, SST

25800500 ACTUATOR, RUBBER,PTT,SST

25800600 ACTUATOR, RUBBER, TACT, SST

02802026 NUT; KNURLED; M4PO.5;/2.5MM JACK

02802027 NUT; KNURLED; M6PO.5/3.5MM JACK

28112401 SCREW 4-40 X 1/4" PHFLST

28233G03 KNURLED NUT, ANTENNA, JMX

CASE BOTTOM ASSEMBLY

13564000 CASE, BOTTOM, PLASTIC, SST 2-PC

2142D021 CONNECTOR, CABLE ASSEMBLY, 2-POS, SST+

25400800 SPRING CONTACT, BATTERY, SST W/O TABSC

25400900 CONTACT BATTERY SST-PLUS (POLARIZED)

25604800 SPACER, PCB, FOAM, SST 2-PC

CASE LABELS

14220001 LABEL, CONTROLS, SST

14222029 LABEL, NAMEPLATE, SST

14290002 BLANK LABEL, .75" X .25" GLOSSY WHITE +

14200037 LABEL SST/JMX MFG DATE CODE

14200039 LABEL FCC SERIAL SST-450

BELT CLIP

25201600 BELT CLIP, PLASTIC, SST BLACK

2811B600 SCREW 6-32 X 1/4" PHTRST

BATTERY PACK AND INSULATOR

BPS-6N-SC BATTERY,RECHG,7.2V NiCd,BLUE ,SST

14230088 LABEL, BATTERY, BPS-6N-SC, SST

25300600 INSULATOR, BATTERY, FIBRE, SST

25606000 FOAM SUPPORT, BATTERY JMX SERIES

25601600 BATTERY SHIM; ASSEMBLY ~X~ SERIES

ANTENNA

AFS-450 ANTENNA UHF MOLDED, 450-470 REG LEN SST

PACKING MATERIALS

14210004 LOW BATTERY NOTICE LABEL

14312006 SHIPPING CARTON, CARDBOARD,SST

14321002 FOAM INSERT, PACKING, SST/MINI

14500008 MANUAL, OWNERS, JMX/SST

14500016 USER MANUAL SST-444

14540006 WARRANTY REGISTRATION CARD

Ritron RIT13-450 UHF-FM Handheld Radio Transceiver User Manual SST 454 THEORY OF OPERATION

Ritron Inc UHF-FM Handheld Radio Transceiver SST 454 THEORY OF OPERATION

Maintenance manual

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