User's Manual

Table Of Contents

Technical Manual Fault Finding

6.5.2 RF Power

Using MXTOOLS increase the ‘Transmit Power’ control to maximum and

check that the output power is greater than +24 dBm.

If the Exciter power is low, check for the +8 V supply voltage at the outputs

of IC2 and TR4.

Use a RF probe to check for gain through IC2 and TR4.

Lift R2 and solder a flying lead to the junction of R1 and R2, check the

output power of the VCO is between 0 and +3dBm.

If all the above tests pass, then return the Exciter Module to your nearest

Customer Service Centre.

6.6 Power Amplifier

First do a visual check of all the components on the PA looking for any

damaged components.

Connect the input of the PA to signal generator with the RF output switched

off.

With PTT off measure the +13.8V supply at the Source of the driver and

output FET. If out of spec then check voltage at CN2-2, no volts then check

supply cable.

With PTT ON measure the PA bias current at the Gates of the FET’s. The

Bias current is band dependent. This is done by monitoring the current drain

of the whole PA with CN1 disconnected. Link the gate of TR2 to GND.

Measure current consumption (VHF High Band 200mA, VHF low And UHF

400mA.) This can be adjusted by RV2. Measure gate volts ≈ 3.4V

Remove link from TR2. Measure current consumption; adjust RV1 so that

current is 2Amp total (VHF & UHF) and VHF Low 1Amp. Measure gate

volts ≈ 3.9V

Connect the RF output Connector CN3 with a coax lead to a power meter.

Turn ON the supply voltage and the signal generator RF output, PTT the PA

and increase the generator output (Don’t exceed +24 dBm) whilst measuring

the output power output (≥50watts@ +24dBM).

If output power is low then turn the supply voltage OFF and lift one side of

the capacitors connecting to the directional coupler and solder a flying lead to

the lifted side. Connect the earth of the flying lead to the earth of the PA.

Connect Power metre to flying lead.

Turn ON the supply voltage and the signal generator RF output, PTT the PA

and increase the generator output (Don’t exceed +24 dBm) whilst measuring

the output power output (≥55watts@ +24dBM).

If all the above tests didn’t pass then the TR1 or TR2 may be faulty. Return to

your nearest Customer Service Centre.