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Technical Manual
♦
Adjust the TCXO to within +/- 20Hz.
♦
If the RX centre frequency cannot be adjusted the TCXO may be faulty.
♦
Distortion should be less than 3%.
♦
If the distortion is high then FL3A, FL3B or FL4 may be faulty.
♦
If the sensitivity is still poor then return the Module to your Service Centre.
6.4 Exciter Module
6.4.1 VCO Locking
♦
Check the reference frequency of X2 (13 MHz) is the same as the TX Reference
Freq. in the 'Hardware Settings' in the built in menu system.
♦
Connect a DVM to the 'TX VCO' TP on the Microcontroller PCB and PTT,
check the Tx locking voltage is between 2 – 14 V.
♦
If the Tx locking voltage is out of spec then slowly adjust L48 on the TX VCO
and check for a change in the locking voltage.
♦
If there is a change in locking voltage, then realign the VCO voltage to 14V at
Upper frequency of the VCO frequency band.
♦
If there is no change in the TX VCO locking voltage then check the VCO supply
voltage TP4 is approx. 7-8V and with a CRO check the TCXO is oscillating on
pin 12 of IC14.
♦
If all the above tests didn't pass then the VCO or IC14 may be faulty. Return the
to your nearest Customer Service Centre.
6.4.2 RF Power
♦
Using in-built menu system increase the 'Transmit Power' control to maximum
and check that the output power is greater than +24 dBm.
♦
To insure power control is at max Short C208 together, (located under SKB)
♦
If the Exciter power is low, check for the +8 V supply voltage at the outputs of
TR27 and TR16.
♦
Lift one side of C216 which leads to R128 and solder a flying lead to that end of
the capacitor, check the output power of the VCO is between ≥ +7dBm.
♦
Use a RF probe to check for gain through TR27 and TR16.
♦
If all the above tests didn't pass, then return to your nearest Customer Service
Centre.
6.5 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.
RELM/
BK RADIO
Installation and Operation
23
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