Vco Tune - Philips FM92E Manual

20: VCO Tune:

Rx Board:
Make sure that you have the 6 metre EPROM installed, connect the speaker, microphone, dummy load (through
a power meter, however you should not see any TX power yet) and 12 volt DC power, then switch on. Connect a
multimeter to the test point below the VCO module, this is TP 201 (positive on pin, negative on case, care should
be taken with your test lead, that it does not short to ground on the module case). If you have a push-on socket,
then that will even be better.
Set the radio to the highest frequency [channel 59], set the multimeter to a 12 volt DC range and with a plastic,
or ceramic tuning tool, adjust the core of the MAIN coil until you get a reading of around 11.7 Volts (not above
12V !). When this has been achieved, key the transmitter and adjust the core of the OFFSET coil until you get a
matching voltage reading. When satisfied that both RX & TX are about the same, select the lowest frequency
[channel 1] and check to make sure the VCO test point voltage is above 4 Volts DC on both RX & TX (we found
ours to be around 5.6 - 7 volts).
Philips FM92E Conversion to 6 Meters: Version 3.9 Page 35