Since the IF frequency is 12.96 MHz, the VFO needs to tune 12.96 MHz below your desired tuning
range on 17 meters (18.000 12.96 = 5.04 MHz). You can use this method to calculate the frequency of
the VFO for your particular tuning selection.
Receiver & Transmitter RF Filter:
The easiest way to tune the RF
input filter is to peak C14 and
C18 in receive mode for loudest
signal while listening to a
relatively constant carrier from
your antenna. This provides both
receive and transmit mode
alignment of this filter.
Transmitter Driver
There is no tuning involved in adjusting the transmitter drivers section, but you do have to set
the bias adjustment. Drive level adjustment will be done in the RF PA alignment section.
1. Connect a 2 to 3 ampere DC ammeter in series with the +12 volt line to your
transceiver.
2. Disconnect the microphone or short it's output so there will be no audio entering
the microphone amplifier.
3. Key the transmitter and note the idling current. Unkey the transmitter.
4. Key the transmitter and slowly adjust R8 for an increase of 20 ma. Unkey the
transmitter.
NOTE: You can alternatively monitor the voltage drop across R7 to
measure idling current in the PA driver amplifier. This is a 2.2
ohm resistor so 20 ma of current would equal a voltage drop
of (0.02 X 2.2 =) 0.044 volts.
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