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

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Document ID	108261
Application ID	0XiEwVzmlU2R8ypMItKm/g==
Document Description	Maintenance manual
Short Term Confidential	No
Permanent Confidential	No
Supercede	No
Document Type	User Manual
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Filesize	24.14kB (301748 bits)
Date Submitted	2000-07-07 00:00:00
Date Available	2000-09-21 00:00:00
Creation Date	2000-07-06 09:33:55
Producing Software	Acrobat Distiller 4.0 for Windows
Document Lastmod	2000-07-06 09:36:49
Document Title	SST-454 THEORY OF OPERATION
Document Creator	Microsoft Word 8.0
Document Author:	Sherri Sawaski

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)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
FCC Identifier.
A copy of the installation and operating instructions.
Type of emission.
Frequency range.
Range of operating power, and means to provide variation in operating power.
Maximum power rating.
DC voltage chart.
Tune-up procedure.
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
RECEIVER
TRANSMITTER
2.
3.
INTRODUCTION
GENERAL
Inspection
Model Identification
FCC REGULATIONS
Licensing
Safety Standards
BATTERY CARE
CHARGING
BATTERY REPLACEMENT
PRECAUTIONS
4.
DESCRIPTION OF CONTROLS AND CONNECTORS
Fig. 2 Controls and Connectors
Belt Clip Installation
10
11
11
5.
OPERATION
On-Off/Volume
Receive
Monitor
Selective Signaling Squelch
Battery Saver
Transmit
Channel Selection
WHAT THE RADIO TONES MEAN
Power On/Self Check “OK
Error Tones
Channel Select
Tone Squelch
Recharge Battery Alert
OPTIONAL RADIO TONES
Receiver Squelch Tone
Busy Channel Inhibit
Transmitter Time Out
TROUBLESHOOTING
General
Battery
Error Tones
Tone Coded Squelch
6.
PROGRAMMING THE RADIO
PTT (PUSH-TO-TALK) PROGRAMMING
Placing the Radio in PTT Programming Mode
How To Find Out What Is Already Programmed
PTT Programming the Radio
PTT Programming Mistakes
Return To Normal Operation
Table 1 – PTT Programming Frequency Table
12
12
12
12
12
13
13
13
13
13
13
13
14
14
14
15
15
15
16
17
17
18
18
18
19
Table 2 – Quiet Call Codes and Frequencies
COMPUTER SOFTWARE COPYRIGHTS
PROGRAMMING THE RADIO USING A PC COMPUTER
Programmable Features
Description of Features
19
19
20
20
21
SST-444 THEORY OF OPERATION
INTRODUCTION
POWER SUPPLY AND VOLTAGE DISTRIBUTION
Power Strobe
Low Battery Voltage Detection
REFERENCE OSCILLATOR
SYNTHESIZER
Pin Numbers
Prescaler Divider / Synthesizer Controller
VCO / Buffer Amplifiers
Oscillator Modulation
DIGITAL POTENTIOMETERS
RECEIVER
RF Amplifier
1st Mixer
FM Receiver Subsystem
Voice / Tone Conditioning in Receiver Mode
Voice Band
Sub-Audible
Audio Amplifier
ANTENNA SWITCHING / LOW-PASS FILTER
TRANSMITTER
Keying
+VTX Supply
Power Amplifier
Voice/Tone Conditioning in Transmit Mode
Voice Band
Sub-Audible
MICROCONTROLLER
22
22
22
22
23
23
23
23
24
24
24
25
25
25
25
25
26
26
26
26
27
27
27
27
27
27
28
28
SST-444 ALIGNMENT PROCEDURE
RECOMMENDED TEST EQUIPMENT
RADIO PREPARATION
REFERENCE FREQUENCY
MODULATION BALANCE
TRANSMITTER TONE DEVIATION
TRANSMITTER VOICE DEVIATION
TRANSMITTER POWER
RECEIVER SENSITIVITY AND SQUELCH
RECEIVER NOISE SQUELCH
SYNTHESIZER
30
30
31
31
31
32
32
32
33
33
SST-444 VOLTAGE CHART
Measurement Conditions
SST-444 Voltages
34
34
10.
SST-444 SCHEMATIC REFERENCE PARTS LIST
40
11.
SST-444 CASE ASSEMBLY PARTS LIST
47
12.
SCHEMATIC AND PART PLACEMENT DRAWINGS
48
7.
8.
9.
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:
Sleep:
Avg. Standby with Power Saver:
Receive:
Transmit:
52 mA
12 mA
24 mA
125 mA
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
Volume Down/Off
Both Volume Buttons
Channel
Single beep when radio is turned on, followed by increasing audio
to adjust volume.
Decreasing audio to adjust volume, with two tones when unit is
turned off.
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.
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
L.O. Injection:
Low side
QC/DQC Decode Time:
per EIA Standards
2nd - 450 KHz
SST-444 SPECIFICATIONS
TRANSMITTER
RF Power Output:
High :
Low:
Programmable per channel for high or low power
4 Watts (3.5 Watts minimum @ +7.2 VDC)
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 460470 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.
Fig. 1
Battery Replacement
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.
10
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.
11
DESCRIPTION OF CONTROLS AND CONNECTORS
Antenna
Jack Cover
Vol Down/Off
Audio Accessory Jack
On/Vol Up
Charge Jack
LD
/H
FF
LU
Push-to-Talk
Speaker
Channel Selector
CH
Microphone
Battery Access Door
(Case bottom)
Fig. 2
Battery Charger Contacts
(Case bottom)
Controls and Accessory Connectors
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.
12
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.
13
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.
14
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.
15
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
As expected.
The radio has been factory or dealer programmed for
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
expected.
Review the battery charging instructions.
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
switched on.
See "Error Tones" in the Operation section.
An error tone sounds while you are talking
(and the transmitter shuts off).
Refer to “Error Tones”
16
OPERATION
TROUBLESHOOTING
Problem
Possible Solutions
Tone Coded Squelch
You cannot screen out calls from users
outside of your tone group.
Make sure the channel is programmed with tone squelch.
Activate Tone (coded) squelch. (Note 7.)
You cannot hear Tone coded messages
while in Tone (coded) squelch.
Confirm that the channel is programmed to detect the
same code as the calling radio(s) transmits. (Note 7.)
Others in your tone group cannot hear your
tone coded messages.
Verify that you transmit the same code as the radio(s) you
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.
17
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.
18
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.
19
PROGRAMMING THE RADIO
Table 1 – PTT Programming Frequency Table
Code
Frequency
Description
Code
Frequency
Description
01
02
03
04
05
06
07
08
09
10
467.7625
467.8125
464.5500
464.5000
467.8500
467.8750
467.9000
467.9250
469.2625
462.5750
Yellow Dot
Brown Dot
Silver Star
Gold Star
Red Star
Blue Star
11
12
13
14
15
16
17
18
19
20
462.6250
462.6750
464.3250
464.8250
469.5000
469.5500
463.2625
464.9125
464.6000
464.7000
Black Dot
Orange Dot
White Dot
Table 2 – Quiet Call Codes and Frequencies
QC
Code
Freq
(Hz)
QC
Code
Freq
(Hz)
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
67.0
71.9
74.4
77.0
79.7
82.5
85.4
88.5
91.5
94.8
97.4
100.0
103.5
107.2
110.9
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
114.8
118.8
123.0
127.3
131.8
136.5
141.3
146.2
151.4
156.7
162.2
167.9
173.8
179.9
186.2
QC
Code
Freq
(Hz)
31
192.8
32
203.5
33
210.7
34
218.1
35
225.7
36
233.6
37
241.8
38
250.3
39
69.4
40
159.8
41
165.5
42
171.3
43
177.3
44 No Tone
45
183.5
QC
Code
Freq
(Hz)
46
47
48
49
50
51
189.9
196.6
199.5
206.5
229.1
254.1
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.
20
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
Automatic Inactivity Turn-off
Battery Saver Enable
Battery Saver Off Time
Beep Volume Level
Beep Fixed Volume Level
Busy Channel Transmit Inhibit
Carrier Only, No Tones or Codes
Channel Selection Mode
Digital Tone Invert RX
Digital Tone Invert TX
Digital Quiet Call (DCS)
Disable Monitor
Channel Beep Rate
Narrow Band Channel
Quiet Call (CTCSS)
Quiet Call Encode Only
Receive Squelch Tone
Squelch Tightener
Transmit Power
Transmit Time Out Timer (60 s)
Turn On To Medium Volume Level
Yes - No
Yes - No
Fixed – Controlled
Yes - No
Increment - Enter
Yes - No
Yes - No
Yes - No
Slow - Fast
Yes - No
See Table 2
Yes - No
Yes - No
Yes - No
Low - High
Yes - No
Yes - No
Standard Setting
Yes
Yes
Fixed
No
Increment
No
No
No
Slow
No
No
No
No
High
Yes
Yes
Per Channel
√
√
√
√
√
√
√
√
√
√
√
√
21
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.
22
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.
23
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
IC301
Y302
IC401
Clock
12
18
Data
19
Latch
20
17
LD
12
T/R SW
11
REF IN REF OUT +5SW
27
10
20
12
+5V
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.
24
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.
25
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 lownoise 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.
26
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.
27
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.
28
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
RESET is connected to the SST-444 +5V to start the radio in a known state on power up.
TX KEY input is pulled LOW when either the internal or external PTT switch is pressed to initiate
transmitter operation.
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.
DATA output sends serial data to frequency synthesizer IC401 to program frequency information,
IC302 EEPROM memory, and to IC306 to set the digital potentiometers.
EECLOCK output sends serial data clock pulses to EEPROM IC302 when reading or writing.
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.
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.
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.
29
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.
30
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:
- FM Deviation Meter
- RF Wattmeter
- Frequency Counter (to 470 MHz)
- SINAD Measuring Device
4) VTVM or DMM
5) RITRON PC Programming Kit
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
Frequency
Mod Bal
Tone
Voice
Power
Alignment
Transmit frequency
Modulation balance
QC/DQC tone encode deviation – wide band
QC/DQC tone encode deviation – narrow band
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
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.
31
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.
32
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.
33
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.
34
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 =
GND =
No connection
Ground
Voltage is strobed in Power Saver mode
→
See note in right column
SOT-23
SST-444 VOLTAGES
DEVICE
PIN
Transmit
Receive
Standby
DESCRIPTION
CR101
0.7
NC
GND
0.0
NC
GND
0.0
NC
GND
TX/RX switching
CR102
GND
GND
0.0
GND
GND
0.0
GND
GND
Voltage clamp
CR103
GND
0.0
0.0
GND
→
< 0.5
GND
Noise detection
→ amplified receiver noise
CR201
1.4
NC
0.7
0.0
NC
0.0
0.0
NC
0.0
CR301
7.5
GND
7.5
GND
7.5
GND
CR302
7.5
2.2
7.5
4.8
7.5
4.8
Reverse voltage protection
CR303
6.8
4.2
6.1
6.8
4.2
6.1
6.8
4.2
6.1
Turn-on detection
CR304
2.0
2.2
2.4
4.7
4.7
5.0
4.7
4.7
5.0
PTT switching
CR305
GND
5.0
0.0
GND
5.0
0.0
GND
5.0
0.0
Voltage clamp
CR306
2.4
NC
2.4
2.4
NC
2.4
2.4
NC
2.4
Voltage clamp
CR307
7.5
0.0
7.5
→
7.5
Reverse voltage protection
→ receive audio amp output
TX/RX switching
Over voltage protection
35
SST-444 VOLTAGE CHART
DEVICE
PIN
Transmit
Receive
Standby
DESCRIPTION
CR401
5.0
4.8
NC
5.0
4.8
NC
NC
CR402
GND
NC
→
GND
NC
→
GND
NC
VCO tuning
CR403
GND
NC
2.4
GND
NC
2.4
GND
NC
VCO modulation
CR404
0.8
NC
0.0
0.0
NC
4.8
NC
TX/RX VCO switching
IC101
10
11
12
13
14
15
16
0.0
NC
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
NC
NC
GND
0.0
4.7
NC
3.8
4.7
3.8
3.8
3.8
4.7
2.0
0.6
2.4
0.0
NC
NC
GND
1.7
NC
NC
NC
GND
RX FM-IF subsystem
IC301
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
5.0
0.0
5.0
0.0
0.0
0.0
0.0
0.0
→
0.0
5.0
5.0
5.0
GND
5.0
4.2
5.0
2.4
0.0
5.0
→
0.0
0.0
NC
0.0
NC
→
5.0
5.0
5.0
0.0
0.0
0.0
0.0
0.0
0.0
→
0.0
0.0
5.0
5.0
GND
5.0
4.2
5.0
2.4
0.5
5.0
2.4
5.0
0.0
NC
0.0
NC
→
5.0
5.0
5.0
0.0
0.0
0.0
0.0
0.0
0.0
→
0.0
5.0
GND
5.0
4.2
5.0
5.0
0.0
0.0
NC
0.0
NC
→
5.0
Microcontroller
Biasing
→ 1.5 – 4.5 VDC VCO tuning voltage
→ 0.0 VDC on Channel 1 else 5.0 VDC
→ 0-5 VDC tone encode waveform
→ 3.6 MHz clock signal
36
SST-444 VOLTAGE CHART
DEVICE
PIN
Transmit
Receive
Standby
DESCRIPTION
IC302
GND
GND
GND
GND
0.0
0.0
GND
5.0
GND
GND
GND
GND
0.0
0.0
GND
5.0
GND
GND
GND
GND
0.0
0.0
GND
5.0
EEPROM
IC303
10
11
12
13
14
2.4
2.4
2.4
5.0
2.4
2.4
2.4
2.4
2.4
2.4
GND
2.4
2.4
2.4
2.4
2.4
2.4
5.0
2.4
2.4
2.4
2.4
2.4
2.4
GND
2.4
2.4
2.4
GND
Audio processing
IC304
10
11
12
13
14
15
16
0.0
2.4
2.4
2.4
0.0
GND
GND
GND
5.0
5.0
5.0
2.4
NC
0.0
0.0
5.0
0.0
2.4
2.4
2.4
2.5
GND
GND
GND
0.0
0.0
0.0
2.4
NC
2.4
2.4
5.0
GND
GND
GND
0.0
0.0
0.0
NC
5.0
Audio signal switching
IC305
2.4
2.4
2.4
GND
2.4
2.4
2.4
5.0
2.4
2.4
2.4
GND
2.4
2.4
2.4
5.0
GND
Audio processing
37
SST-444 VOLTAGE CHART
DEVICE
PIN
Transmit
Receive
Standby
DESCRIPTION
IC306
10
11
12
13
14
15
16
17
18
19
20
2.0
3.8
GND
0.0
2.4
2.4
2.4
0.0
5.0
GND
NC
0.0
2.4
2.4
2.4
2.4
2.4
4.0
5.0
5.0
2.0
0.0
GND
2.5
2.4
2.4
2.4
0.0
5.0
GND
NC
0.0
2.4
2.4
2.4
2.4
2.4
4.0
5.0
5.0
GND
GND
NC
Audio signal level control
IC307
NC
0.0
GND
GND
0.0
0.0
0.0
NC
NC
0.0
GND
GND
3.7
7.5
3.7
NC
NC
0.0
GND
GND
0.0
0.0
0.0
NC
Audio amplifier
IC308
2.4
2.4
GND
5.0
2.4
2.4
5.0
3.2
2.4
2.4
GND
5.0
2.4
2.4
5.0
3.2
GND
Tone low pass filter
IC309
7.5
GND
7.5
NC
5.0
7.5
GND
7.5
NC
5.0
7.5
GND
7.5
NC
5.0
+5 VDC voltage regulator
38
SST-444 VOLTAGE CHART
DEVICE
PIN
Transmit
Receive
Standby
DESCRIPTION
IC401
10
11
12
13
14
15
16
17
18
19
20
→
5.0
NC
NC
5.0
→
GND
2.2
NC
2.4
2.4
5.0
NC
5.0
0.0
NC
5.0
5.0
0.0
2.2 →
→
5.0
NC
NC
5.0
→
GND
2.2
NC
2.4
2.4
5.0
NC
5.0
0.0
NC
5.0
5.0
0.0
2.2 →
→
NC
NC
5.0
GND
NC
NC
5.0
NC
5.0
Q 101
5.0
5.0
0.0
4.3
5.0
4.7
RX +V switching
Q 102
0.0
GND
0.0
0.7
GND
3.0
GND
RX RF amplifier
Q 103
0.0
0.0
0.0
4.7
0.0
1.8
Q 104
0.0
GND
0.0
0.7
GND
1.2
GND
RX IF amplifier
Q 105
0.0
GND
0.0
0.7
GND
4.6
GND
RX 2
Q 201
6.8
7.5
6.0
7.5
7.5
0.0
7.5
7.5
0.0
TX +V switching
Q 202
5.0
4.3
6.8
0.0
0.0
7.5
0.0
0.0
7.5
TX +V switching
Q 203
0.0
3.8
7.5
0.0
GND
0.0
0.0
7.5
0.0
GND
0.0
0.0
7.5
0.0
GND
Q 204
0.9
0.3
6.0
0.0
0.0
0.0
0.0
0.0
0.0
→ 3.6 MHz clock signal
Frequency synthesizer
→ 1.5 – 4.5 VDC VCO tuning voltage
→ 14.4 MHz reference signal
RX mixer
nd
LO multiplier/amp
TX RF final amplifier
TX RF driver amplifier
39
SST-444 VOLTAGE CHART
DEVICE
PIN
Transmit
Receive
Standby
DESCRIPTION
Q 301
5.0
GND
0.0
0.0
GND
5.0
0.0
GND
5.0
PTT detection
Q 302
4.3
5.0
5.0
5.0
5.0
0.0
5.0
5.0
0.0
PTT detection
Q 303
5.0
4.3
6.8
5.0
4.3
6.8
5.0
4.3
6.8
Battery +V switching
Q 304
6.8
7.5
7.5
6.8
7.5
7.5
6.8
7.5
7.5
Battery +V switching
Q 306
4.3
5.0
5.0
4.3
5.0
5.0
5.0
5.0
+5V switching
Q 307
0.0
0.0
7.5
5.0
4.3
6.8
0.0
0.0
7.5
Audio amplifier enable
Q 308
7.5
7.5
0.0
6.8
7.5
7.5
7.5
7.5
0.0
Audio amplifier +V switching
Q 401
0.7
GND
2.9
0.7
GND
2.9
GND
VCO buffer amplifier
Q 402
0.7
GND
2.8
0.7
GND
2.8
GND
VCO buffer amplifier
Q 403
2.3
1.6
4.3
2.3
1.6
4.3
VCO oscillator
Q 404
4.7
4.3
5.0
4.7
4.3
5.0
VCO voltage de-coupling
Q 405
0.0
4.3
4.2
4.3
4.3
0.0
TX/RX VCO switching
Q 406
0.0
GND
4.3
4.3
GND
0.0
GND
TX/RX VCO switching
40
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
Y Theta
Loc
CAPACITORS
C101
C102
C103
C104
C105
C106
C107
C108
C109
C110
C111
C112
C113
C114
C115
C116
C117
C118
C119
C120
C121
C122
C123
C124
C125
C126
C127
C128
C129
C130
C131
C132
C133
C134
C135
C201
C202
C203
C204
C205
C206
C207
C208
C209
C210
C211
C212
C213
C214
C215
C216
C217
C301
151103A3
151102A2
15110120
15110220
15110180
15110180
15181102
15181102
151106A8
151103A9
151103A3
151103A3
15110100
151108A2
15110150
15182103
15110150
15110470
15181472
151108A2
15181102
152B6106
15181102
15181102
15119104
15119104
15119104
15119104
15119104
15182103
15110330
15110330
15119104
15182103
15110220
15180101
15181102
15180101
152A8105
15181102
15180101
15181102
15110100
15119104
15180101
15110560
15110101
151103A9
15110100
15110101
151105A6
15181102
3.3pf NPO 0805 CHIP CAPACITOR
2.2PF NPO 0805 50V CHIP CAP
12PF NPO 0805 50V CHIP CAP
22PF NPO 0805 50V CHIP CAP
18PF NPO 0805 50V CHIP
18PF NPO 0805 50V CHIP
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
6.8PF NPO 0805 50V CHIP
3.9PF NPO 0805 50V CHIP
3.3pf NPO 0805 CHIP CAPACITOR
3.3pf NPO 0805 CHIP CAPACITOR
10PF NPO 0805 50V CHIP CAP
8.2PF NPO 0805 50V CHIP
15PF 0805 NPO 50V CHIP CAP
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
15PF 0805 NPO 50V CHIP CAP
47PF NPO 0805 50V CHIP
.0047uF CAPACITOR, CHIP, 0402, X7R,5/10%
8.2PF NPO 0805 50V CHIP
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
10uF 10V 3.4 X 2.8 CHIP TANTALUM
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.1uF X7R 0805 25V CERAMIC CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
33PF NPO 0805 50V CHIP
33PF NPO 0805 50V CHIP
.1uF X7R 0805 25V CERAMIC CHIP CAP
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
22PF NPO 0805 50V CHIP CAP
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
1MFD 16V ~3.2 X 1.6~ CHIP TANTALUM
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
10PF NPO 0805 50V CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
100pF CAPACITOR, CHIP, 0402, COG, 5%
56PF NPO 0805 50V CHIP CAPACITOR
100PF NPO 0805 50V CHIP CAP
3.9PF NPO 0805 50V CHIP
10PF NPO 0805 50V CHIP CAP
FACTORY SELECT
100PF NPO 0805 50V CHIP CAP
5.6PF NPO 0805 50V CHIP CAPACITOR
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
1065
949
791
909
1018
869
734
675
637
557
516
382
476
275
380
276
199
160
485
407
138
451
450
349
350
441
69
225
392
571
38
64
69
39
171
1302
871
997
1100
1019
1748
1748
1796
1427
1492
1715
1788
1682
1652
1439
953
1035
774
3824
3929
4059
3824
3608
3716
3620
3519
3994
3993
4099
4099
3993
4059
3786
3382
3598
3491
3367
3548
947
1669
946
884
1364
1557
2203
2114
1802
904
1263
1156
2100
1635
1533
3153
3384
3248
3496
3494
3308
3104
2406
2284
2264
2211
3787
3828
4093
4093
4136
4136
817
270
180
90
270
270
180
180
90
90
270
180
180
270
270
180
180
90
270
90
90
270
90
270
90
180
90
270
90
270
90
90
90
90
90
90
270
90
180
90
90
90
90
180
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Bottom
Bottom
Top
Top
Bottom
Bottom
Top
Bottom
Bottom
Top
Top
Top
Top
Top
Top
Top
Bottom
41
SST-444 SCHEMATIC REFERENCE PARTS LIST
Ref
Ritron PN
Description
C302
C303
C304
C305
C306
C307
C308
C309
C310
C311
C312
C313
C314
C315
C316
C317
C318
C319
C320
C321
C322
C323
C324
C325
C326
C327
C328
C329
C330
C331
C332
C333
C334
C335
C336
C337
C338
C339
C340
C341
C342
C343
C344
C345
C346
C347
C348
C349
C350
C351
C352
C353
C354
C355
C356
C357
C358
C359
C360
C361
C362
15181102
152B4226
15181102
15180101
15180101
15182103
15111102
15182103
15119104
15181102
15182103
15181102
15181102
15181102
15182103
15181102
15181102
15181102
15181102
15181102
15180101
15181102
15119104
15180101
15180101
15181102
15181102
15181102
15181102
15181102
15181102
152A6475
15119104
15180101
15181102
152B6106
15180101
15119104
15111333
15182103
15110821
15111122
15181472
15181472
152A8105
15180180
15119473
15111333
15180101
15181222
15180100
15182103
15180221
15181102
15181102
15181102
15181102
15180100
15181102
15180101
15119104
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
22uF 6.3V 3.4 X 2.8 CHIP TANTALUM CAP
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
.001MF X7R 0805 50V CHIP CAP
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
.1uF X7R 0805 25V CERAMIC CHIP CAP
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.1uF X7R 0805 25V CERAMIC CHIP CAP
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
4.7UF 10V A-SIZE TANTALUM CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
10uF 10V 3.4 X 2.8 CHIP TANTALUM
100pF CAPACITOR, CHIP, 0402, COG, 5%
.1uF X7R 0805 25V CERAMIC CHIP CAP
.033MFD X7R 0805 50V CHIP CAP
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
820PF NPO 0805 50V CHIP CAP
.0012MF X7R 0805 50V CHIP
.0047uF CAPACITOR, CHIP, 0402, X7R,5/10%
.0047uF CAPACITOR, CHIP, 0402, X7R,5/10%
1MFD 16V ~3.2 X 1.6~ CHIP TANTALUM
18pF CAPACITOR, CHIP, 0402, COG, 5%
.047uF X7R 0805 25V CHIP CAPACITOR
.033MFD X7R 0805 50V CHIP CAP
100pF CAPACITOR, CHIP, 0402, COG, 5%
.0022uF CAPACITOR, CHIP, 0402, X7R,5/10%
10pF CAPACITOR, CHIP, 0402, COG, 5%
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
220pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
10pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
.1uF X7R 0805 25V CERAMIC CHIP CAP
275
199
1261
1027
613
20
496
1107
1229
544
169
1280
1280
826
704
826
704
1280
1280
1280
1280
969
1280
1280
1280
704
638
704
704
737
502
95
420
454
724
254
245
366
585
638
637
184
269
614
286
474
127
493
19
436
593
379
301
258
153
585
490
470
492
981
Y Theta
522
647
4590
427
402
4621
1867
3264
2967
4622
3033
2568
2271
2291
2321
2371
2407
2410
2488
2311
2771
2221
2687
2607
2371
2446
2501
2571
2610
2672
2703
2765
2842
3156
3558
3129
2945
2665
2328
2964
3045
2436
2436
2232
2500
2595
2621
3156
2670
3228
3133
2436
2435
2393
2415
2498
2589
2270
2074
752
270
180
90
270
270
90
90
270
270
180
180
180
180
180
180
180
180
180
180
180
270
270
180
180
270
90
270
90
270
270
270
180
180
90
90
90
90
180
90
180
90
90
90
180
90
90
270
270
Loc
Top
Top
Bottom
Top
Top
Top
Bottom
Bottom
Bottom
Bottom
Top
Top
Bottom
Bottom
Top
Bottom
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Bottom
Bottom
Top
Top
Bottom
Bottom
Bottom
Bottom
Top
Top
Top
Top
Top
Bottom
Bottom
Top
Top
Top
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Top
Top
Bottom
42
SST-444 SCHEMATIC REFERENCE PARTS LIST
Ref
Ritron PN
Description
Y Theta
C363
C364
C365
C366
C367
C368
C369
C401
C402
C403
C404
C405
C406
C407
C408
C409
C410
C411
C412
C413
C414
C415
C416
C417
C418
C419
C420
C421
C422
C423
C424
C425
C426
C427
C428
C429
C430
C431
C432
C433
C434
C435
152B6106
15119104
01503212
15119104
15119104
15181102
15180101
15180101
151101A5
15181102
15181102
15180101
151101A5
151104A7
151104A7
15119104
151104A7
15180101
15181102
151101A8
152B6106
15181102
15180101
15180101
15180101
15181102
15181102
15180101
15110100
151101A0
151108A2
15180101
15111222
152AB334
15180101
15111333
15180101
15182103
15180101
15180101
15180101
15180101
48D100A2
48E1005G
48A1005C
48D100A2
48B61012
48AA01SA
48A1005B
48A100A3
48A1005C
48A1005C
48AA01SA
48A1005C
48C1004E
48C1004G
48A1004D
Loc
10uF 10V 3.4 X 2.8 CHIP TANTALUM
.1uF X7R 0805 25V CERAMIC CHIP CAP
220MF 10V ELT CAPACITOR, 5mm HEIGHT
.1uF X7R 0805 25V CERAMIC CHIP CAP
.1uF X7R 0805 25V CERAMIC CHIP CAP
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
1.5PF NPO 0805 50V CHIP
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
1.5PF NPO 0805 50V CHIP
4.7PF 0805 50V CHIP CAP.
4.7PF 0805 50V CHIP CAP.
.1uF X7R 0805 25V CERAMIC CHIP CAP
4.7PF 0805 50V CHIP CAP.
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
1.8PF NPO 0805 50V CHIP
10uF 10V 3.4 X 2.8 CHIP TANTALUM
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
.001uF CAPACITOR, CHIP, 0402, X7R, 5/10%
100pF CAPACITOR, CHIP, 0402, COG, 5%
10PF NPO 0805 50V CHIP CAP
1.0PF NPO 0805 50V CHIP
8.2PF NPO 0805 50V CHIP
100pF CAPACITOR, CHIP, 0402, COG, 5%
.0022uF X7R 0805 50V CHIP CAPACITOR
.33MF 35V ~3.2X1.6~ CHIP TANTALUM
100pF CAPACITOR, CHIP, 0402, COG, 5%
.033MFD X7R 0805 50V CHIP CAP
100pF CAPACITOR, CHIP, 0402, COG, 5%
.01uF CAPACITOR, CHIP, 0402,Z5U,5/10/20
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
100pF CAPACITOR, CHIP, 0402, COG, 5%
1231
1058
1491
1482
1357
247
664
1566
1640
1680
1066
1353
1182
1463
1572
980
1355
1262
1047
1462
722
1535
1731
1538
677
678
678
1053
1119
1256
1187
1069
832
812
855
1029
971
687
766
932
1101
687
427
503 180
5052 0.302
659
90
798
90
2708 270
2454
90
1966 270
194
90
1828
90
1850 180
2013 180
1785 270
1604
1634 270
1766
90
158 270
130 270
1788
90
1441 270
1625
969 270
1114 270
1356
90
1121 180
1201 180
1240 180
1576 180
1512 180
1400
1252 270
937
90
922 180
1015
1473 270
1015
1460 270
1393 180
1100 180
1460
90
1264
1355 180
Top
Bottom
Top
Bottom
Bottom
Bottom
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
MA4CP101A PIN DIODE, SOT-23
MMBD-352LT1 SCHOTTKY DIODE SOT23
MMBD7000, DUAL DIODES IN SERIES, SOT-23
MA4CP101A PIN DIODE, SOT-23
1N4742A ZENER DIODE, 12V 1W DL-41 MELF
DIODE, 1A, 50V, SMT, D0214AC CASE
MMBD6100, DUAL DIODES, COM CATHODE, SOT2
MMBD2835, DUAL DIODES, COM ANODE, SOT-23
MMBD7000, DUAL DIODES IN SERIES, SOT-23
MMBD7000, DUAL DIODES IN SERIES, SOT-23
DIODE, 1A, 50V, SMT, D0214AC CASE
MMBD7000, DUAL DIODES IN SERIES, SOT-23
MMBV-105G DIODE VVC, SOT-23
MMBV-2101L DIODE VVC SOT-23
MMBV3401 PIN/UHF DIODE SOT-23
1178
908
356
1302
991
1154
363
65
626
449
1290
695
1147
1119
1552
3820
3608
2147
3991
604
630
431
4089
2802
2956
630
1808
1115
1400
1239
Top
Top
Bottom
Top
Top
Top
Top
Top
Bottom
Bottom
Top
Top
Top
Top
Top
DIODES
CR101
CR102
CR103
CR201
CR301
CR302
CR303
CR304
CR305
CR306
CR307
CR401
CR402
CR403
CR404
90
270
90
90
90
90
90
90
180
180
270
43
SST-444 SCHEMATIC REFERENCE PARTS LIST
Ref
Ritron PN
Description
06000040
WIRE; #40AWG TINNED BUS (INCHES)
Y Theta
Loc
FUSE
F301
754
603
270
Bottom
31030003
314G0301
31210005
310K0004
311K0003
310K0003
310K0001
31010004
310K0002
310E0002
313K0004
MC3371D SUBSYSTEM IC, SO-16
314
MCU, 28 PIN, SOIC, SST/JMX 4-SERIES v01
992
EEPROM, 512X8, 24C04
989
LMV324MT RAIL TO RAIL QUAD OP AMP
474
SWITCH,ANALOG,TRIPLE SPDT,4053,TSSOP-16
241
LMV358MM DUAL OP AMP, GP LV R/R TSSOP
404
DS1806E 6 PROG POTS 10K OHM 20-PIN TSSOP
242
LM386MX-1 AUDIO AMP SO-8
1331
MAX7410 5TH ORDER SW CAP BUTTERWORTH LPF 407
REGULATOR,LDO,LP2980,5V,W ENABLE,SOT-25
162
SYNTHESIZER TSSOP MC145192
891
1158
2546
2501
2442
2683
3120
2185
567
2935
504
1265
270
180
180
90
180
Bottom
Bottom
Top
Top
Top
Top
Top
Bottom
Top
Top
Top
02100001
02100053
2.5MM PC-MT JACK; ANT-CHGR
3.5MM STEREO JACK; PANEL MOUNT
1178
1560
4668
4646
1.5T SW COIL W/5MM SHIELD & ALUM CORE
CHIP INDUCTOR .15uhy
1.5T SW COIL W/5MM SHIELD & ALUM CORE
1.5T SW COIL W/5MM SHIELD & ALUM CORE
3T AIRCOIL, SMT, 8.0nH, .120 X .145
CHIP INDUCTOR 1.0uhy
1T AIRCOIL, SMT 2.5nH, .120 X .145
CHIP INDUCTOR .68uhy
4.5T AIRCOIL #24AWG .0625” ID RHH SMT
INDUCTOR, CHIP, 15nH
4.5T AIRCOIL #24AWG .0625"ID RHH SMT
4.5T AIRCOIL #24AWG .0625"ID RHH SMT
CHIP INDUCTOR 1.0uhy
5.5T AIRCOIL #24AWG .0625"ID RHH SMT
2T AIRCOIL SMT 5.0nH .120 X .145
9T AIRCOIL, SMT, 9.85 nH, .159 X .056
9.5T AIRCOIL #24AWG .0625"ID RHH SMT
INDUCTOR, CHIP 82nH
CHIP INDUCTOR 0.1uhy
CHIP INDUCTOR 0.1uhy
721
629
484
204
332
280
480
51
929
1454
1695
1479
1230
1093
932
1376
1352
1548
1187
753
4291
3722
4291
4292
3901
3474
3492
1648
3459
2281
3948
3945
3667
3979
4343
1418
118
109
966
1485
90
270
270
270
180
180
180
270
180
90
180
90
270
270
270
Top
Top
Top
Top
Top
Top
Top
Bottom
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Bottom
CONTACT, PCB MNT, ANTENNA,SST
HEADER, 2 PIN SIDE ENTRY SHROUDED
896
754
4550
737
90
MMBT3906 PNP, SOT23
TRANSISTOR, NPN, UHF, SOT-23, PBR-941
MMBFJ309LT1, N-CHAN, RF, SOT23
MMBT918LT1 VHF SOT23 (3B)
675
734
340
270
3405
3828
3639
3548
270
270
INTEGRATED CIRCUITS
IC101
IC301
IC302
IC303
IC304
IC305
IC306
IC307
IC308
IC309
IC401
JACKS
J301
J303
Top
Top
INDUCTORS
L101
L102
L103
L104
L105
L106
L107
L108
L201
L202
L203
L204
L205
L206
L207
L401
L402
L403
L404
L405
01850201
18110151
01850201
01850201
18433103
18110102
18433101
18110681
18414104
18110150
18414104
18414104
18110102
18414105
18433102
18433209
18414109
18110820
18110101
18110101
MICROPHONE
M301
05500037
MICROPHONE; ELECTRET, MINIATURE
CONNECTORS
P201
P302
25500700
21310021
Top
Top
TRANSISTORS
Q101
Q102
Q103
Q104
4801002A
482100V0
4841006U
4821003B
Top
Top
Top
Bottom
44
SST-444 SCHEMATIC REFERENCE PARTS LIST
Ref
Ritron PN
Description
Y Theta
Loc
Q105
Q201
Q202
Q203
Q204
Q301
Q302
Q303
Q304
Q306
Q307
Q308
Q401
Q402
Q403
Q404
Q405
Q406
4821003B
4801002A
4801001Q
04801503
482100V0
48010R02
4801002A
4801001Q
480100DH
4801002A
4801001Q
480100DH
482100V0
482100V0
482100V0
4801001Q
4801006A
48010R02
MMBT918LT1 VHF SOT23 (3B)
MMBT3906 PNP, SOT23
MMBT5088 NPN, SOT-23
M68710H 2W RF MODULE 450-470 MHz 6.0V
TRANSISTOR, NPN, UHF, SOT-23, PBR-941
MUN2211T1, NPN, INT 10K/10K BIAS, "8A",
MMBT3906 PNP, SOT23
MMBT5088 NPN, SOT-23
BCW68GLT1 .8AMP PNP SOT-23
MMBT3906 PNP, SOT23
MMBT5088 NPN, SOT-23
BCW68GLT1 .8AMP PNP SOT-23
TRANSISTOR, NPN, UHF, SOT-23, PBR-941
TRANSISTOR, NPN, UHF, SOT-23, PBR-941
TRANSISTOR, NPN, UHF, SOT-23, PBR-941
MMBT5088 NPN, SOT-23
MUN2111T1, PNP, INT 10K/10K BIAS, SC-59
MUN2211T1, NPN, INT 10K/10K BIAS, "8A",
38
908
766
1819
1603
1133
1094
583
445
1222
964
1162
1470
1289
1460
837
1634
1691
1374
3268
3268
2710
2274
2987
3124
519
668
2259
615
712
1919
1920
1714
1766
1376
1234
180
90
270
90
270
90
90
90
270
270
270
270
270
Bottom
Bottom
Bottom
Top
Top
Bottom
Bottom
Top
Top
Top
Bottom
Bottom
Top
Top
Top
Top
Top
Top
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
3.9K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
560 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1.5K OHM RESISTOR, CHIP, 0402, 1/16W,5%
1.5K OHM RESISTOR, CHIP, 0402, 1/16W,5%
22K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
100 OHM RESISTOR, CHIP, 0402,1/16W,5%
150K OHM RESISTOR, CHIP, 0402, 1/16W,5%
1.2K OHM RESISTOR, CHIP, 0402, 1/16W,5%
220K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
12K OHM RESISTOR, CHIP, 0402, 1/16W,5%
1.5K OHM RESISTOR, CHIP, 0402, 1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
39K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
680 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
470 OHM RESISTOR, CHIP, 0402, 1/6W, 5%
180 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
27 OHM 0805 CHIP RESISTOR
8.2K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1.8K OHM RESISTOR, CHIP, 0402, 1/16W,5%
180 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
470 OHM 0805 CHIP RES.
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
579
734
774
829
714
475
388
251
167
411
529
349
489
551
161
161
117
79
59
78
790
669
908
1796
1555
1618
1184
879
536
475
325
623
402
535
995
1127
1257
704
504
704
3344
3581
3716
3810
3519
3610
3484
3450
3450
946
904
966
946
966
2174
2089
1676
1533
1470
1635
3384
3248
3151
2211
2244
2264
3549
4148
686
479
546
639
547
1867
3143
3328
2891
2191
4622
2230
90
180
270
270
270
270
180
180
180
270
270
180
90
270
90
90
90
180
90
90
270
90
270
270
270
90
90
270
90
270
270
90
90
180
270
270
Top
Top
Top
Top
Top
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Top
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Top
Top
Top
Top
Top
Top
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Bottom
RESISTORS
R101
R102
R103
R104
R105
R106
R107
R108
R109
R110
R111
R112
R113
R114
R115
R116
R117
R118
R119
R120
R201
R202
R203
R204
R205
R206
R207
R208
R301
R302
R303
R304
R305
R306
R307
R308
R309
R310
R311
R312
47180103
47180103
47180102
47180392
47180561
47180152
47180152
47180223
47180101
47180154
47180122
47180224
47180123
47180152
47180104
47180103
47180393
47180103
47180102
47180681
47180103
47180471
47180181
47100270
47180822
47180182
47180181
47180102
47180103
47100471
47180104
47180102
47180104
47180103
47180103
47180103
47180103
47180104
47180104
47180103
45
SST-444 SCHEMATIC REFERENCE PARTS LIST
Ref
Ritron PN
Description
R313
R314
R315
R316
R317
R318
R319
R320
R321
R322
R323
R324
R325
R326
R327
R328
R329
R330
R331
R332
R333
R334
R335
R336
R337
R338
R339
R340
R341
R342
R343
R344
R345
R346
R347
R348
R349
R350
R351
R352
R353
R354
R355
R356
R357
R358
R359
R401
R402
R403
R404
R405
R406
R407
R408
R409
R410
R411
R412
R413
R414
47180104
47180472
47180102
47180103
47180103
47180104
47180471
47180471
47180103
47180393
47180823
47180224
47180104
47180183
47180183
47180103
47180153
47180100
47180104
47180154
47180473
47180273
47180102
47180104
47180103
47180224
47180394
47180104
47180104
47180184
47180473
47180104
47180104
47180102
47180274
47180473
47180823
47180564
47180222
47100475
47180103
47180102
47180103
47180273
47180102
47180153
47180100
47180221
47180101
47180272
47180102
47180101
47180272
47180470
47180470
47180271
47180153
47180153
47180102
47180472
47180103
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
4.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
470 OHM RESISTOR, CHIP, 0402, 1/6W, 5%
470 OHM RESISTOR, CHIP, 0402, 1/6W, 5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
39K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
82K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
220K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
18K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
18K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
15K OHM RESISTOR, CHIP, 0402, 1/16W,5%
10 OHM RESISTOR, CHIP,0402, 1/16W 5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
150K OHM RESISTOR, CHIP, 0402, 1/16W,5%
47K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
27K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
220K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
390K OHM RESISTOR, CHIP, 0402, 1/6W, 5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
180K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
47K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
270K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
47K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
82K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
560K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
2.2K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
4.7M OHM 0805 CHIP RESISTOR
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
27K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
15K OHM RESISTOR, CHIP, 0402, 1/16W,5%
10 OHM RESISTOR, CHIP,0402, 1/16W 5%
220 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
100 OHM RESISTOR, CHIP, 0402,1/16W,5%
2.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
100 OHM RESISTOR, CHIP, 0402,1/16W,5%
2.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
47 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
47 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
270 OHM RESISTOR, CHIP, 0402, 1/16W, 5%
15K OHM RESISTOR, CHIP, 0402, 1/16W,5%
15K OHM RESISTOR, CHIP, 0402, 1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
4.7K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
Y Theta
1184
1260
738
761
800
704
737
698
636
294
371
332
416
585
624
493
168
664
269
207
246
566
60
23
532
397
420
340
239
153
731
67
153
732
568
529
29
29
431
44
453
847
912
1293
1147
1187
1482
1517
1640
1450
1452
1153
1193
1086
1067
1636
1266
1363
1271
677
1634
2376 270
2375 270
2841
90
2557
90
2506
90
2521 180
2756 270
2879 270
2899
3070 270
3070 270
3070 270
3156
90
2413 270
2328
90
2774 270
2374
90
2369
90
2396
2501
90
2500
90
2588
90
2787 270
2787 270
3156 270
3228
90
2347 270
2436
90
2455
2376 180
3133
2416 180
2455 180
3094 180
2588
90
2589
90
2146
2198
2269
90
2406
2158 180
653 180
772
90
780
90
534
90
534
90
773 270
2006
90
1828 270
2013 180
1825 180
1900 270
1900 270
1788 270
1726 180
1655
90
162 5180
1694 270
1827 180
1903
1531 270
Loc
Top
Top
Bottom
Top
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Top
Top
Top
Top
Top
Top
Top
Bottom
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Bottom
Bottom
Top
Top
Top
Top
Top
Bottom
Bottom
Bottom
Bottom
Bottom
Bottom
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
Top
46
SST-444 SCHEMATIC REFERENCE PARTS LIST
Ref
Ritron PN
Description
R415
R416
R417
R418
R419
R420
R421
R422
R423
47180102
47180104
47180102
47180473
47180822
47180103
47180223
47180100
47180474
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
100K OHM, RESISTOR, CHIP, 0402,1/16W,5%
1K OHM RESISTOR, CHIP,0402, 1/16W,5%
47K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
8.2K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
10K OHM, RESISTOR, CHIP, 0402,1/16W,5%
22K OHM RESISTOR, CHIP, 0402, 1/16W, 5%
10 OHM RESISTOR, CHIP,0402, 1/16W 5%
470K OHM RESISTOR, 0402, 1/16W, 5%
Y Theta
Loc
1641
1138
938
938
718
718
1101
894
850
1068
1576
937
1022
906
946
1303
1461
1100
90
90
90
180
90
180
Top
Top
Top
Top
Top
Top
Top
Top
Top
SWITCH SPST MOMENTARY MINI PC 260GM
SWITCH SPST MOMENTARY MINI PC 260GM
SWITCH, TACT LO PROFILE RT ANGLE 160gf
SWITCH, TACT LO PROFILE RT ANGLE 160gf
268
788
82
82
4587
4588
3097
3948
180
180
270
270
Top
Top
Top
Top
455KHZ IF TRANSFORMER (5MM)
128
1822
180
Top
TCVCXO, 14.400 MHz, 1.5 PPM, VC=30 PPM/V
146
837
90
Top
43.650 MHz Crystal Filter +/-6.0KHz UM-1
FILTER,CERAMIC,450KHz,+/-7.5KHz,6 POLE
44
249
3524
1614
90
90
Top
Top
SPEAKER
SP301 05500045
SPEAKER, 45MM, 1W, LOW PROFILE SST/RTX
Bottom
SWITCHES
SW301
SW302
SW303
SW304
05100042
05100042
05100046
05100046
TRANSFORMER
T101
05600018
CRYSTAL
Y302
23050003
FILTERS
YF101
YF102
02301403
02301013
HARDWARE
1750240B
25602500
06001021
06001023
06001026
06001029
25105500
25603000
25603900
25605700
25900700
26200800
26200900
2811H401
PCB, ML4 FR4 5UPM, .062 MIX, SST-444
CRYSTAL SUPPORT, RUBBER PAD, SMALL/UM-1
#28 AWG STRANDED WIRE; RED (INCHES)
#28 AWG STRANDED WIRE;GREEN INCHES
#28 AWG STRANDED WIRE; BLACK INCHES
#28 AWG STRANDED WIRE; BLUE INCHES
SHIELD, SST-PLUS SYNTHESIZER
FOAM, MOUNTING, SPEAKER,SST
SPACER, MIC FOAM, SST
MICROPHONE HOLDER, SST-PLUS
ADHESIVE, MTG, MIC HOLDER
HEATSINK, TOP, SST+
HEATSINK, BOTTOM, SST+
SCREW #4-40 X .25 LG TRIM HEAD PHILLIPS
47
SST-444 CASE ASSEMBLY PARTS LIST
Ref
Ritron PN
Description
MAIN CASE ASSEMBLY
13250000
13578000
13588000
25106400
25201500
25400600
25603300
25603400
25606200
25800500
25800600
02802026
02802027
28112401
28233G03
CASE W/INSERT, PLASTIC, SST BLACK
DOOR, BATTERY, PLASTIC, SST 2-PC
LATCH, BATTERY DOOR, PLASTIC SST 2-PC
BATTERY DOOR HINGE RETAINER
RETAINER, PLASTIC, PTT, SST
BUSHING, THREADED, PLATED, ANTENNA SS
GRILLE CLOTH, SPEAKER, SST
DUAL JACK PLUG, RUBBER,SST
HINGE, BATTERY DOOR, SST
ACTUATOR, RUBBER,PTT,SST
ACTUATOR, RUBBER, TACT, SST
NUT; KNURLED; M4PO.5;/2.5MM JACK
NUT; KNURLED; M6PO.5/3.5MM JACK
SCREW 4-40 X 1/4" PHFLST
KNURLED NUT, ANTENNA, JMX
CASE BOTTOM ASSEMBLY
13564000
2142D021
25400800
25400900
25604800
CASE, BOTTOM, PLASTIC, SST 2-PC
CONNECTOR, CABLE ASSEMBLY, 2-POS, SST+
SPRING CONTACT, BATTERY, SST W/O TABSC
CONTACT BATTERY SST-PLUS (POLARIZED)
SPACER, PCB, FOAM, SST 2-PC
CASE LABELS
14220001
14222029
14290002
14200037
14200039
LABEL, CONTROLS, SST
LABEL, NAMEPLATE, SST
BLANK LABEL, .75" X .25" GLOSSY WHITE +
LABEL SST/JMX MFG DATE CODE
LABEL FCC SERIAL SST-450
BELT CLIP
25201600
2811B600
BELT CLIP, PLASTIC, SST BLACK
SCREW 6-32 X 1/4" PHTRST
BATTERY PACK AND INSULATOR
BPS-6N-SC
14230088
25300600
25606000
25601600
BATTERY,RECHG,7.2V NiCd,BLUE ,SST
LABEL, BATTERY, BPS-6N-SC, SST
INSULATOR, BATTERY, FIBRE, SST
FOAM SUPPORT, BATTERY JMX SERIES
BATTERY SHIM; ASSEMBLY ~X~ SERIES
ANTENNA
AFS-450
ANTENNA UHF MOLDED, 450-470 REG LEN SST
PACKING MATERIALS
14210004
14312006
14321002
14500008
14500016
14540006
LOW BATTERY NOTICE LABEL
SHIPPING CARTON, CARDBOARD,SST
FOAM INSERT, PACKING, SST/MINI
MANUAL, OWNERS, JMX/SST
USER MANUAL SST-444
WARRANTY REGISTRATION CARD
48

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File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.3
Linearized                      : No
Modify Date                     : 2000:07:06 09:36:49-05:00
Create Date                     : 2000:07:06 09:33:55-05:00
Title                           : SST-454 THEORY OF OPERATION
Author                          : Sherri Sawaski
Creator                         : Microsoft Word 8.0
Producer                        : Acrobat Distiller 4.0 for Windows
Page Count                      : 48

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