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crystal frequency. Once the "L" frequency mode has been set, momentarily pressing the AFA button
will repeat this "long" frequency measurement.
The 20m version uses an 11.059 MHz crystal, while the 30m version uses a 13.065 MHz crystal.
Measured frequency variations of 2 to 3 KHz from the specified crystal frequency are not unusual.
Set the spot switch to the "off" position. Set the RIT pot to one extreme and press the AFA button and
record the frequency. It should be close to the desired crystal frequency. Set the RIT pot to the other
extreme, press the AFA button and record the second frequency. The difference between the first
frequency and the second frequency should be at least 2 KHz, and represents total tuning range of the
RIT. If the spot switch is not set to the "off", but rather in the "on" position, the RIT pot will not cause
the VXO frequency to move. For these tests, the spot switch must be in the "off" position.
The RIT pot has a center detent. Set the RIT pot to this center position and measure the frequency. We
will now set the T/R offset trim post to a frequency 600 Hz lower than this frequency. Thus, by default,
when the RIT pot is centered in the center detent position, there will be a 600 Hz offset between transmit
and receive. To do this, set the spot switch on and tune the VXO T/R offset on board trim pot R53 (see
the detail on the VXO section) until the frequency is 600 Hz lower than just measured.
Later on, when the receiver is finished, you can take a signal and tune it in to where it "sounds right" to
you (your preferred pitch). Then using the spot switch in the "spot" position, trim pot R53 can be
adjusted until the received signal is zero beat. At that point, the transmit/receive offset will be adjusted
to your preference, which may not be a 600 Hz offset.
This series of tests verifies VXO, T/R offset, and AFA circuitry that has been built thus far.
Disconnect the 9v battery supply.
Disconnect the temporary wire connection installed above!
Norcal NC2030 v5
12-18-05
Page 58 of 128
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