RF Technology T70A VHF Transceiver User Manual users manual

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Eclipse Series
T7OIT150 Transmitter
Operation and Maintenance
RF TECHNOLOGY PTD. LTD,
FCC 1D: KRET70A
JOB #: 182U0
EXHIBIT #: I a
T7OIT150 - Operation and Maintenance
CONTENTS
Page
Operating Instructions 5
Internal Jumper Options 7
I/O Connections 8
Programming 9
Circuit Description 10
Alignment Procedures 15
Specifications 18
Appendix A — Parts List 24
Block Diagram 30
Schematic Diagrams
Exciter 31
66 — 88 MHz Power Amplifier 32
136 —l74 Mhz Power Amplifier 33
Board Layout
Exciter 34
66 — 88 MHz Power Amplifier 35
136 -174 Mhz Power Amplifier 36
RF1TI}BKMXX?YPTD,LTD
FCC ID: KRET70A
JOB #: ISZUO
EXHHHT#1 £5
RF Technology Pty. Ltd. 05/9118 R13 Issue 5 Page 3
T7OIT150 -- Operation and Maintenance
Operating Instructions
PTT -
The PTT button is used to key the transmitter during system test and
adjustment. Audio from the line input is automaticaly disabled so that an
unmodulated carrier with subaudible tone is transmitted.
LINE -
The LINE trimpot is used to set the line and direct audio input level. It is
normally set to give 60% of system deviation with 0 dBm (775 mV ) input at
1 KHz. The level can be measured between test socket pins 6 & 1 and
adjusted for inputs of -30 to +10 dBm,
An internal jumper provides a coarse adjustment step of 20 dB. This, in
conjunction with the trimpol, allows the level to be accurately set over a wide
range.
PWR LED —
The PWR LED shows that the do supply is connected to the transmitter.
TX LED -
The TX LED indicates that the transmitter is being keyed, the synthesizer is
locked and the output amplifier is enabled.
ALARM LED ~
The ALARM LED can indicate the detection of several different fault
conditions by the self test circuits. The alarm indicator shows the highest
priority fault present.
For transmitters using software issue number 5 and higher the alarm
condition is indicated by the cadence of the LED flesh.
LED Cadence Fault Condition
Flash 5 times, pause Synthesizer unlocked
Flash 4 times, pause Tuning voltage range
Flash 3 times, pause Low forward power
Flash 2 times, pause High reverse power
Flash 1 times, pause Low dc supply voltage
LED ON continuously Transmitter timed out
RF TECHNOLOGY PTD. LTD.
FCC ID: KRET70A
JOB#1 iszuo Q/
RF Technology Pty. Ltd. 05/9116 R13 Issue 5 Page 5 EXHIBIT #:
T70/T150 - Operation and Maintenance
For transmitters using issue number 4 or lower the alarm condition is
indicated by the flash rate.
LED indication
Flashing, 8 per second
Flashing, 4 per second
Flashing, 2 per second
Flashing, 1 per second
Continuous
ALC LED —
Synthesizer unlocked
Tuning voltage range
Low forward power
High reverse power
dc supply voltage low
or high
The ALC LED indicates that the transmitter output power is being controlled
by an external amplifier through the external ALC input.
REF LED -
The REF LED indicates that the synthesizer frequency reference is locked to
an external reference,
TEST MIC.
The TEST MIC. DIN socket is provided for use with a standard mobile or
handset 200 Ohm dynamic microphone. The external audio inputs are
disabled when the TEST MiCt's PTT is on.
RF Technology Pty. Ltd. 05/9116 R13 Issue 5 Page 6
JPZ -
JP3 -
JP4-
JP6 —
JP7 -
JP8-
T70/T150 -- Operation and Maintenance
Transmitter internal Jumper Options
EPROM Type
270256
27064
600 Ohm Line dc Loop PTT Input
dc Loop Connected
dc Loop Not Connected
Audio Input Source Selection
GOO Ohm Line input
Hi-Z Balanced input
Input Level Attenuation
0 dB
20 dB
Audio Frequency Response
750 uSec. Pre—emphasis
Flat Response
Subaudible Tone Source
Internal CTCSS
External Input
Em
2-3 *
1-2
JP9, JP10, JPI1 dc Loop PTT ll‘iput Configuration (JP3 1-2)
Current Loop Input
+12 Vdc Loop Source
* = Standard Ex-anctory Configuration
OFF
JPIO J 11
OFF OFF *
ON ON
RF TECHNOLOGY PI'D. LTD.
FCC 1D: KRE'WOA
JOB #: 182U0
EXHIBlT #: 2
RF Technology Pty. Ltd. 05/9116 R13 Issue 5 Page 7
T70/T150 - Operation and Maintenance
T7OIT150 Transmitter IIO Connections
25 Pin Connector
Function/Signal
dc Power +12 Vdc
-12 Vdc
Channel Selection
R8232 Serial Data input
600 Ohm Line High
150 Ohm/Hybrid Connections
Direct PTT input
T/R Relay Driver Output
Hi-Z Audio input +
Sub-Audible Tone Input +
External ALC input
20
7,19
16
401.41;
Specification
+114 to 16 Vdc
BCD Code
0 = Open Circuit
or 0 Vdc
1: +5 to +16Vdc
Test & Programming
9600, 8 data 2 stop
bits
Transformer Isolated
Balanced 0 dBm input
Switch to ground to
key the transmitter
Open collector
switch, 250mA, 30V
High impedance AC
coupled direct input
1 - 250 Hz input
ALC input for Power
amplifiersDecreases
from 7V with
increasing power
RF TECHNOLOGY Pro
FCC 1D: KRET70A ' LTD'
JOB #: 13on
EXHIBIT #: l
RF Technology Pty. Ltd. 05/9116 R13 issue 5 Page 8
T70/T150 -K Operation and Maintenance
Channel and Tone Frequency Programming
Channel and tone frequency programming is most easily acomplished with
R.F.Techno|ogy TecHelp software. This software can be run on any IBM
compatible PC and provides; a number of additional useful faciliities.
TecHeip provides a simple means of calibrating the forward and reverse
power detectors and alarms.
TecHeIp can be supplied by your dealer, distributor
or by contacting RF. Technology directr
RF mcrmomoY pro. cm
FCC m; KRET70A
JOB it: 132110
EXHIBIT #: i
RF Technology Ply. Ltd. 05/9116 R13 issue 5 Page 9
T70/T150 - Operation and Maintenance
Circuit Description
The following descriptions should be read as an aid to understanding the
block and schematic diagrams at the rear of this manual.
VCO Section A
The Voltage Controlled Oscillator uses a junction FEET Q19 which oscillates at
the required transmitter output frequency. Varactor diodes D25 and D26 are
used by the PLL circuit to keep the oscillator on the desired frequency.
Transistor QZO is used as an active filter to reduce the noise on the oscillator
supply voltage, ’
The VCO is keyed ON by the microcontroller through 010. It is keyed ON
when any of the PTT inputs are active and OFlF at all other times.
The VCO output is amplified and buffered by monolythic amplifiers MA2 and
MAS before being fed to the PLL lC U6.
Amplifiers MA1, MA4 and MA5 increase the VCO output to approximately 10
mW to drive the power amplifier. MA1 is not switched on until the PLL has
locked and had time to settle. This prevents any momentary off channel
transmission when the transmitter is keyed.
PLL Section -
The frequency reference for the synthesizer is a crystal oscillator using
transistors Q26 and 027 and crystal Y3. The temperature stability is better
than 5 ppm and it can be synchronized to an external reference for improved
stability. External reference option board 11/9119 is required when using an
external reference.
A positive temperature coefficient thermistor, XH1, is used in versions
intended for operation down to ~30 degrees Celsius. The thermistor heats the
crystal's case to maintain its temperature above —1(l degrees thus extending
the oscillator stability of 5 ppm down to -30 degrees; ambient.
Varactor diodes D27-30 are used to frequency moclulate the oscillator. The
processed transmit audio signal from U7b varies the diodes bias voltage to
modulate the reference frequency. This extends the modulation capability
down to a few Hz for sub-audible tones and digital squelch codes. A two point
modulation scheme is used with the audio also being fed to the VCO to
modulate the higher audio frequencies.
The the 12.8 MHz output of 027 is amplified by QZEland Q29 to drive the
reference input of the PLL synthesizer IC U6. This lC is a single chip
synthesizerwhich includes a 1.1 GHz pre-scaler, programmable divider,
reference divider and phase/frequency detector The frequency data for U6 is
supplied through serial data link by the microprocessor,
The phase detector output signals of us are used to control two switched
current sources. The output of the positive and negative sources' Q3 and OS,
produce the tuning voltage which is smoothed by the loop filter components
to bias the V.C.O. varactor diode D3.
RF TECHNOLOGY PTD. LTD.
FCC ID: KRET70A
1013111 182U0 H
RF Technology Pty. Ltd. 05/9116 R13 Issue 5 Page 10 Em‘w'j’
T7OIT150 -- Operation and Maintenance
Power Amplifier -
The 10 mW output from the main board connects to the power amplifier
board through a short miniature 50 Ohm coaxial cable.
Q2 on the power amplifier board increases the signal to approximately
200 mW. The bias current of 02 is controlled by Q1 and the power leveling
circuitry to adjust the drive to the output module U2,
U2 increases the power to 30 watts before it is fed to the directional coupler,
low pass filter and output connector. The directional coupler detects the
forward and reverse power components and provides proportional dc
voltages which are amplified by IJ1a and U1 b. ’
The forward and reverse voltages from U1a and U1b are compared to the DC
reference voltage from RVt. The difference is amplified by U1c, Q3 and 04
The resulting control voltage supplies Q2 through R10, R12 and completes
the power leveling control loop,
Temperature Protection -
Thermistor RT1 on the power amplifier board is used to sense the case
temperature of the output module U2. if the case temperature rises above 90
degrees C., the voltage across FlT1 will increase and transistor 05 will be
turned on. This reduces the dc reference voltage to the power regulator which
inturn reduces the outpower by 63—10 dB.
600 Ohm Line input -
The 600 Ohm balanced line input connects to line isolation transformer T1.
T1 has two 150 Ohm primary windings which are normally connected in
series for 600 Ohm lines. The dual primary windings can be used to privide
DC loop PTT signalling or a 2/4 wire hybrid connection. All four leads are
available at the rear panel system connector.
The secondary of T1 can be terminated with an internal 600 Ohm load
through JP5 or left unterminated in high impedance applications.
Direct Coupled Audio input —
A high impedance( 10k) direct AC coupled input is available at the system
connector. The direct coupled input connects to U9a which is configured as a
unity gain bridge amplifier.
The bridge configuration allows audio signal inversion by interchanging the
positive and negative inputs and minimizes ground loop problems. Both
inputs should be connected, with one lead going to the source output pin and
the other connected to the source audio ground.
RF TECHNOLOGY P’I'D. LTD.
FCC ID: KRET70A
JOB #: 182U0
EXHIBIT #: j}_
RF Technology Pty. Ltd. 05/9116 R13 issue 5 Page 11
T7OIT150 - Operation and Maintenance
Local Microphone input -
The local microphone input is provided for use with a standard low
impedance dynamic microphone. The microphone output is amplified by U9a
before connecting to analog switch U10a. Utob inverts the local microphone
PTT input to switch U10a ON when the microphone PTT button is pressed.
U10a is OFF at all other times.
The local microphone audio has priority over the other inputs. Activation of
the local microphone PTT input switches OFF the audio from the line or direct
inputs through D16 and U10c,
CTCSS and Tone Filter —
The CTCSS encoder module H1 is a microcontroller based hybrid module.
Under control of the main microprocessor U13 it can encode all 38 E.l.A.
tones and 12 additional commonly used tones.
The tone output of H1 connects to jumper JPS which is used to select either
H1 or an external tone source. The selected source is coupled to U9c which
is a balanced input unity gain amplifier. The buffered tone from U9c is fed to
300 Hz low pass filter U7c. RV3, the tone deviation trimmer, is used to adjust
the level of the tone from U7c before it is combined with the voice audio
signal in the summing amplifier U7a.
Back to back diodes 04 and D5 limit the maximum tone signal amplitude to
prevent excessive tone deviation when external tone sources are used.
Audio Signal Processing -
Jumper JP4 selects either the line or direct input source. The selected source
is then connected to JP6. JP8 can be removed to provide 20 dB attenuation
when the input level is above 10 dBm to expand the useful range of the line
level trimmer RV4,
The wiper of RV4 is coupled to the input of the input amplifier U9d. U9d
Bree/ides a votlage gain of ten before connecting to the input of analog switch
c.
The outputs of U10a and Uioc are connected to the frequency response
shaping networks 052, R133 (750 uSec. pre-eimphasis) and C61,R55 (flat).
JP? selects the pre-emphasised or flat response.
The audio signal is further amplified 100 times by U7d. U7d also provides the
symetrical clipping required to limit the maximum deviation. The output level
from U7d is adjusted by RV1, the deviation adjustment, before being
combined with the tone audio signal in the summing amplifier U7a.
The composite audio from U7a is fed through the 3Khz low pass filter U7b.
The filtered audio is coupled to the TCXO voltage tuning input and the
modulation balance trimmer RV2.
RV2 adjusts level of the audio used to modulate the VCO. This primarily
effects the deviation of audio frequencies above 500 Hz. RV2 is used to
balance the high and low frequency deviation to obtain an flat frequency
response relative to the desired characteristic.
RF TECHNOLOGY FTD. LTD.
FCC ID: KRET70A
JOB #: 182U0
RF Technology Pty. Ltd, 05/9116 R13 Issue 5 Page 12 EXHIBIW: 7 j
T70lT150 -- Operation and Maintenance
PTT and DC Remote Control -
Two main PTT inputs are provided. The first, a direct logic level input, is
connected to pin 3 of the system connector. The transmitter can be keyed by
applying a logic low or ground on pin 3. Pin 3 connects to the PTT loglc and
microprocessor through D10.
DC current loop control can be used for remote PTT operation. The current
loop can be configured by JP9, JP10 and JP11 for use with either a remote
free switch or a remote switched source.
Opto-isolator lSOt is used to isolate the loop current signal from the
transmitter PTT logic. The loop current passes through the input of lSOi and
the output of ISO1 connects to the PTT logic.
A bridge consisting of diodes D6, D8, D9 and D14 ensures correct operation
regardless of the current polarity. 017 limits the current and D7 limits the
voltage input to lSOt.
Any low voltage current source capable of providing 2 mA at 4 V or switching
circuit with less than 4.8K Ohms loop resistance can be used to switch the DC
loop.
The test PTT button on the front panel and the local microphone PTT button
will also key the transmitter. Both of these also mute the line audio input.
Microprocessor Controller -
The microprocessor controFer circuit uses an advanced eight bit processor
and several support chips. The processor U13 includes non-volitile EE
memory for channel frequencies, tones, and other information. it also has an
asynchronous serial port, a synchronous serial port and an eight bit analog to
digital converter.
The program is stored in US, a (ZJMOS EPROM. U4 is an address latch forthe
low order address bits. U2 is used to read the channel select lines onto the
data bus. U11 is an address decoder for U5 and U2. U3 is a supervisory chip
which keeps the processor reset unless the +5 Volt supply is within operating
iimitls. U1 translates the asynchronous serial port data to standard RS232
eve s.
The analog to digital converter is used to measure the toward and reverse
power, tuning voltage and dc supply voltage.
The processor keys the VCO through 010, switches the 9.2 Volt transmit line
through 014 and 016, and the alarm LED D1 through 01.
Voltage Regulator -
The dc input voltage is regulated down to 9.4 Vdc by a discrete regulator
circuit. The series pass transistor 023 is driven by error amplifiers 08 and
018. 09 is used to start up the regulator and once the circuit turns on, it plays
no further part in the operation.
RF TECHNOLOGY PTD. LTD.
FCC iD'. KRET70A
JOB #: iszuo
RF Technology Pty. Ltd. 05/9116 R13 Issue 5 Page 13 EXHIBIT til—ZA-
T70/T150 - Operation and Maintenance
This circuit is short circuit and overload proof by virtue of the component
current and power ratings, The maximum current and dissipation rating of the
pass transistor can not be exceeded under any load condition.
The descrete component circuit provides much better line isolation and lower
dropout voltage than can be obtained with current integrated circuit
regulators.
The +5 Volt supply for the logic circuits is provided by an integrated circuit
regulator U14 which is run off of the regulated 94 Volt supply,
RF TECHNOLOGY P'I'D. LTD.
FCC l'D: KRET70A
JOB #: 182U0
E)G-II'BIT #:
RF Technoloov Ptv. Ltd. 05/9116 R13 issue 5 l‘age 14

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