AES 7085 VE Users Manual

AES Corporation does not have a “user’s manual” for this device. The only manual that is available is a

“service manual” because of the intended use and sale of this product. This service manual is provided

below.

AES

7085-VE

VHF

SYNTHESISED

DATA TRANSCEIVER

Service Manual

40-7085-VE-SM Document Rev A1 10/2003

AES Corporation

285 Newbury Street. Peabody, Massachusetts 01960-1315

Tel [phone]. Fax [phone]

Copyright 2003, All rights Reserved

TABLE OF CONTENS

1. SPECIFICATION

2. CONNECTIONS AND OPERATION

3. CIRCUIT DESCRIPTION 4-

4. PERFORMANCE TEST AND ALIGNMENT

5. TEST EQUIPMENT CONFIGURATION

6. TRANSMITTER PERFORMANCE TEST

7. TROUBLESHOOTING

8. PROGRAMMER INSTRUCTION

9. PARTS LIST

22-35

17-19

20

13

14-16

2

3

12

12

10. PRINT CIRCUIT BOARD LAYOUT

11. PARTS ASSE MBLY

12. BLOCK DIAGRAM

13. SCHEMATICS DIAGRAM

44-49

50

51

36-43

PAGE 1

1. SPECIFICATION

GENERAL SPECIFICATIONS

POWER SOURCE +12VD.C. nominal (+10.8 to +15.6V )

TEMPERATURE RANGE

STORAGE 80ºC maximum -40ºC min.

25ºC nominal

OPERATING 60ºC maximum -20ºC min.

ANTENNA IMPEDANCE 50Ω

FREQUENCY CONTROL PLL SYNTHESISER

FREQUENCIES OF OPERATION 140MHZ - 174MHZ

FREQUENCY TOLERANCE AND STABILITY ±1.5PPM

HIGH HUMIDITY 90%

CHANNEL CAPABILITY 1

NOMINAL DIMENSIONS 134 mm (L) X60 mm (W) X20 mm (H)

WEIGHT 190g

RADIO DATA TRANSCEIVER NOMINAL PERFORMANCE

PERFORMANCE SPECIFICATIONS ETSI 300-113

RF OUTPUT POWER 5W/1W PROGRAMMABLE

MODULATION TYPE FM

INTERMEDIATE FREQUENICES 45 MHZ

455 KHZ

CHANNEL SPACING 12.5 KHZ , 6.25 KHZ (PROGRAMMABLE)

TRANSMIT ATTACK TIME < 25 mS

CURRENT CONSUMPTION

TRANSMIT 1500mA@5W, 800mA@1W

RECEIVE 85mA

PAGE 2

2. CONNECTIONS AND OPERATION

EXTERNAL CONNECTIONS

1-

50Ω BNC SOCKET

9 PIN “D” TYPE PLUG (J501)

2-

D-TYPE INTERCONNECTIONS

J501-1 DATA_IN ANALOGUE 100Mv-2.5VP-P EXTERNAL MODULATION INPUT
J501-2 DATA_OUT ANALOGUE 1VP-P RECEIVER AF OUTPUT
J501-3 PTT INPUT 0V/+5V TRANSMIT ENABLE
J501-4 GND GND 0V GND
J501-5 B+ V+ +13.8V POWER SUPPLY
J501-6 CDS OUTPUT OPEN/SHORT RF CARRIER DETECT
J501-7 NC NC NC NC
J501-8
J501-9 PGM_ENB INPUT 0V/5V PROGRAMMING ENABLE

PGM_DATA

INPUT 0V/NC PROGRAMMER DATA INPUT

PAGE 3

3. CIRCUIT DESCRIPTION

TRANSMITTER

The transmitter is comprised of:

• Audio amplifier connections from J501 pin 1

• Frequency Synthesizer

• Transmitter

• Automatic Power Control

Audio frequency connections

Processed data from the IC504 is applied to the VCO via P305 and applied to the TCXO
P701

Frequency synthesizer circuit

With data received from the EEPROM (IC502) the frequency synthesizer circuit controls
and Produces the RF carrier frequency for the transmitter during transmit and the local
oscillator frequency for the receiver. The frequency synthesizer circuit is comprised of:

• 12.8 MHZ Tcxo

• Voltage Controlled Oscillator (VCO) module

• Charge Pump and Loop Filter

• PLL Frequency Synthesizer

• Dual Modulus Prescaler

PAGE 4

PLL Synthesizer

The PLL synthesizer circuit is common to both the transmitter and receiver.

The synthesizer comprises:

TCXO

DC-DC

Converter

Data

IC1

PLL

Charge Pump

Loop Filter

RF Out

TX OR RX

VCO

Voltage controlled oscillator module (VCO)

The module contains two VCOs. One for producing carrier frequencies during transmit (TX
VCO) and one for producing the local oscillator frequency during receive (RX VCO). The
module also has RX and TX power line filters. Output is for PLL IC(IC1) Fin.

PAGE 5

RX and TX power line filters

Transistor Q308 is configured as a 5v power supply ripple filter. The filter reduces the noise
on the carrier and local oscillator signals.

RX

VCO

The RX VCO comprises JFET Q301, coil L301 , and varactor D301 and is configured as a
Colpitts Oscillator . D301 produces a change in frequency with a change in DC voltage and
is controlled by The tuning voltage signal present at the cathode. The local oscillator signal
at the source of Q301 is Applied to the cascode buffer/amplifier formed by Q16 and Q17.The
Local signal is applied to the Mixer when diode D2 is reverse biased and D3 is forward
biased.

TX VCO

The TX VCO comprises JFET Q301,coil L303 , and varactor D302 and D303 and is
configured as A Colpitts oscillator . D302 produces a change in frequency with a change in
DC voltage and is controlled by the tuning voltage signal present at the cathode. The AF
signal at J501 pin 1 is applied to the cathode of D303 to produce FM modulation. When
diode D2 is forward biased and D3 is reversed biased the modulated RF signal at the
collector of Q16 is passed to the power Amplifier and harmonic filter via the cascade
buffer/amplifier (Q21 and Q22).

PLL IC

The reference frequency from the TCXO, at 12.8 MHZ, is connected to pin 1 of IC1 (MB1504)
The appropriate VCO is connected to pin 11.

REFDIV divides the 12.8 MHz to produce a reference frequency (Fr) of 5 or 6. 25 kHz
dependent upon channel spacing selected. VARDIV divides the prescaled VCO frequency to
produce a variable frequency (Fv). Fv and Fr are fed to the phase detector.

Phase detector

When Fv=Fr, the phase detector output (pins 15 and 16,IC1) produces narrow negative
pulses And Fv and Fr pulse widths are identical. When FvFr pin 15 (V) pulses negative with
pin 16 (R) remaining high. When FvFr pin 16 (R) pulses negative with pin 15(V) remaining
high. The signal at pin 15 and 16 is smoothed the loop filter and applied to the VCO.

Out-of-lock detector

T

he out-of-lock detector produces a series of logic level pulses when the
loop is out of lock at pin 7 of IC1.The pulses at pin 7 of IC1 are buffered by
Q6 and then integrated by R17 and C19. The product of the integrating
circuit is fed to IC501 pin 25.

PAGE 6

Charge Pump and Loop Filter

Transistors Q2, Q4, Q10, and associated resistors and capacitors form
the charge pump and loop Filter. The phase detector output from IC1
pins 15 and 16 are combined by the charge pump to produce a 0 to
15V tuning voltage signal.
The signal is filtered by the loop filter (R13, C16 and C17) to remove
any residual reference Frequency harmonics from the signal. After
filtering the signal is applied to the voltage controlled Oscillator
module.

DC to DC Converter

The DC-to-DC converter converts the +7.5 V to a 14-16 V supply. This
is used to provide the Tuning voltage for the VCO. A wide voltage
range is required to allow for the wideband operation of the radio.
Q506 to Q508, and associated components, form a 200kHz oscillator.
The output of the oscillator is rectified and filtered by D503, D506,
C548 and C11. The resultant 16VDC is passed to R544 and then
becomes the supply rail for the charge pump.

Dual modulus prescaler

The prescaler divides the VCO frequency by 64 or 65.

Transmitter
The transmitter comprises:

VCO Buffer PA Module

Amp

Automatic

Power Control

RF LPF

ANTENNA

SWITCH

PAGE 7

Buffer

When the radio is in transmit mode the diode D2 is forward biases enabling the modulated RF signal

from the VCO to pass to the buffer/pre-amplifier Q21 and Q22 and associated components.

The output signal is passed from Q22 to IC5 via a matching network consisting of Inductor L7 and

C73.

PA module

The signal is then amplified for transmission by IC5, which is a power amplifier module.

Low pass filter

The amplified RF signal is passed through the stripline coupler and is fed to the harmonic low pass

filter, comprising L12 to L15 and C94-C98 and then to the antenna connector (ANT). The stripline

coupler provides a sample of the RF signal for the automatic power control.

Antenna Switch

When transmitting, the diodes D5 and D6 are forward biased, allowing the RF to pass to the antenna.

D6 is shorted to ground which makes L11 look open circuit (1/4 wave tuned stub). This prevents the

TX signal from passing to the receiver stage.

Automatic power control (APC) circuits

The automatic power control contains the stripline coupler, diode D4, variable resistor RV1, U4A

and transistors Q19 and Q23.

The RF signal present in the coupler is rectified by D4, to produce a DC voltage. This DC voltage is

passed to one input of IC4A, which is a differential amplifier. In transmit mode a DC reference level

for U4A is supplied by the potential divider R34/R35.

The reference level and the detected level from D4 are compared a difference signal is produced. The

difference signal drives Q19, which then drives Q23. Q23 controls the supply voltage to the first

amplifier stage in IC5. This control loop produces a constant power output at the antenna connector

( ANT ).

RV1 is used to adjust the voltage that is fed back from D4 which defines the output RF power level.

PAGE 8

Receiver

The receiver comprises:

Front End

Amp

ANTENNA

SWITCH

Rx

VCO

First Mixer

IF Filter

IF Amp

Second

Mixer

Local

Oscillator

Data Out

Audio Filter

FM

Limiter-

Discriminator

IF

Filter

PAGE 9

Squelch

Circuit

Antenna Switch

In receive, the diode D5 and D6 are reverse biased. L11 is now in circuit, passing the signal from the

antenna to the front end without signal loss.

Front End

The receiver signal is routed to pin 1 of the RF Front End module. It passes through the band pass

filter consisting of C800 to C808/L800 to L803.

Diode D800 serves as protection from RF overload from nearby transmitters.

The input signal is coupled to the base of Q800, which serves as an RF amplifier.

The output of Q800 is then coupled to a second band pass filter consisting of C814 to C822 / L804 to

L806.

The output of the front end module, pin6, is then coupled to the double-balanced mixer IC8.

The receiver front end module is factory pre-tuned and requires no adjustment.

Repair is effected by replacement of the entire module.

First Mixer

IC8, 2-pole crystal filters XF1 and XF2 and coils L16 and L18 form the First Mixer and First IF

Filter.

IC8 is a self-contained double balanced mixer. The RF signal, from the front end is applied to pin 4

and the VCO local oscillator signal is applied to pin 1.

The difference frequency of 45 MHz is taken from pin 5 and is filtered by the crystal filters XF1 and

XF2. The tuned circuits L16 and L18 and associated components provide matching of the crystal

filters to ensure a good pass-band response and selectivity.

The IF signal is amplified by Q24 and passed to the FM Detector IC.

Second mixer, Second IF, FM detector

The output of the IF amplifier is fed into the narrowband FM IF Integrated Circuit, IC6 (MC3371).

This is a single conversion FM receiver which contains the second mixer, second IF amplifier, and

FM detector.

PAGE 10

Crystal X1, connected to pin 1 of IC6, determines the second local oscillator frequency. In this case

the crystal has a frequency of 44.545MHz. The first IF signal is applied to the mixer and resultant

frequency of 455KHz, is the difference between the IF signal and second local oscillator.

The 455KHz IF signal is output from pin 3 and is applied to a 455KHz band-pass filter, CF1 (12.25

kHz channel spacing) or CF2 (6.25 kHz channel spacing). The selection of the filters is

accomplished by diodes D13 (input) and D14 (output) whose bias is controlled by software and

applied to the diodes from pin 21 of IC501.

The output of CF1/CF2 is passed via pin 5 to a high gain IF amplifier coupled to the adjustable

quadrature detector T2 (pin 8). Any detected signal is produced at pin 9 of IC6 and applied to the

Receiver Audio Circuit and the Mute (Squelch) Circuit.

Squelch (MUTE) Circuit

The noise detect circuit in conjunction with IC6 consists of diode D11 and RV2.

Any noise signal is amplified by IC6 internal noise amplifier rectified by D11 .D11 Signal is applied

to pin12 of IC6. The squelch trigger output (pin 14,IC6) is applied to the pin 6 of J501.

When noise is present, the voltage at pin 12 of IC6 is less than 0.7V. The squelch trigger output is

0V(logic 0) It’s make pin 6 of J501 open state.

When no noise is present, the voltage at pin 12 of IC6 exceeds 0.7v and pin 14 of IC6 IS AT

5v(logic 1). This make pin 6 of J501 short state.

Carrier Detect

A Carrier Detect (MUTE DETECT) output is available on pin 6 of J501.

AF Output Low Pass Filter

A low pass filter formed by C134, C135 and R82 removes any extraneous 455kHz energy from the

AF output of the FM receiver chip (pin 9 of IC6).

The filtered signal is passed to pin 2 of J501.

Micro controller

The PIC 16C57 microcontroller IC controls the programmable features and frequency synthesizer

data.

PAGE 11

Programming Mode

The programming mode allows the user to retrieve or program TX/RX frequencies, HI/LO power

Setting and channel spacing, when pin 9 of J501 is set to ground. Programming mode will Inhibit,

Serial communications can then be made in order to read/program the on- board EEPROM

( IC502 )which contains radio- specific data.

EEPROM

Relevant channel information, such as RX / TX frequencies, is stored in the EEPROM (IC502)

which is a 93C46. This information may be programmed and erased via the D- type socket. The

EEPROM has 1024 (8x128) capacity and is written serially.

Power supply circuit

The data radio is supplied with a nominal + 13.8V dc power supply input from external equipment

which is filtered using C532 ,L501 and C533.This supply is converted into three separate voltage

levels on the board using the switching transistor Q506 and associated components .

The +13.8Vdc supply and Q506 switching waveform are summed using D503 to supply a boosted

voltage supply, which is regulated at +16V using Zener diode D506. This supply is used as the

supply for the tuning voltage for the VCOs.

The +6V line is regulated by Zener diode D505 and filtered using L503 and C538.This +6V line is

fed to the RF circuit and is regulated to +5V using two regulators on the board.

4. PERFORMANCE TEST AND ALIGNMENT

The alignment and performance test procedures assume the use of the following equipment.

Discrete test equipment

Volt Meter Spectrum Analyzer and notch filter (option)

RF Power Meter. Coupler (20dB isolation)

DC Power Supply, 0-15V 2A min

Oscilloscope, 20 MHz dual beam

RF Frequency Counter,

100 kHz - 600 MHz

AF Signal Generator 0 – 20 kHz

RF Signal Generator

SINAD Meter

Modulation Meter

Audio Power Meter

PAGE 12

5. TEST EQUIPMENT CONFIGURATION.

RF Signal Generator

Watt Meter with

20dB Attenuator

Audio Generator

Modulation Meter

SINAD Meter OSCILLOSCOPE

RADIO

VOLT Meter

Spectrum Analyzer

DC Power Supply

Frequency Counter

Test Box

123.45678

Test Equipment Configuration PAGE 13

6. TRANSMITTER PERFORMANCE TESTS

Power Output

1. Set the power supply voltage to 13.8V DC and monitor the voltage during transmit.

2. Switch data radio TX and check and record the output power. The nominal output power is

adjustable between 1 and 5W depending on the programming.

3. Set the PTT switch to OFF.

Peak Deviation

1. 1. Connect the oscilloscope to the output of the modulation meter.

2. Set the AF signal generator to 100 Hz at 5Vpeak–to-peak and connect to DATA _IN Line (pin 1

of J501)

3. Switch data radio to TX and observe the oscilloscope display to check that the 100Hz tone is a

square wave.

4. Using the AF signal generator, sweep from 100 Hz to 3 kHz and record the peak deviation.

5. Check the peak deviation for appropriate channel spacing as follows:

For 12.5 kHz channel spacing, Peak deviation is not greater than 2.5 kHz.

For 6.25 kHz channel spacing, Peak deviation is not greater than 2 kHz.

Spectrum Test

It may be necessary to notch the fundamental signal during this test.

1. Connect a spectrum analyzer and RF power meter to the antenna socket.

2. Switch data radio to TX. Observe the output spectrum on the spectrum analyzer.

3. Adjust notch filter to minimize the carrier. All spurious and harmonics signals should be below-

36 dBm up to 1 GHz and below –30 dBm between 1 and 4 GHz.

4. Switch off the data radio transmit control.

Receiver Performance Tests

Sensitivity

The SINAD performance test may be used to test the sensitivity of the receiver.

1. Connect the RF signal generator to the data radio BNC antenna connector.

2. Set the RF signal generator to the receive frequency .

3. Connect the leads of the SINAD meter between 0 V and pin 2 on J501.

4. Set the deviation to 60% of the peak system deviation.

5. Set the AF generator to 1 kHz.

6. Adjust the RF signal generator level until the SINAD Meter reads 12 dB.

7. Check that the signal generator RF level is less than 0.35uV pd (-116 dBm).

PAGE 14