SG-2000 MANUAL
153
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receiving quality.
Note: the next steps are not necessary if all previous steps were successful.
Fine tune the 82 MHz filter using a Spectrum Analyzer (see 82 MHz filter
calibration described above).
Turn the power supply to the radio OFF.
Connect RF output of the Tracking Generator to point A on the Exciter with 0
dB output 84.00 MHz.
Connect RF input of the Spectrum Analyzer to point B on the Exciter with the
attenuator set to 20 dB, scan width = 2 MHz per division, 10 dB Log scale, scan
mode = internal, scan trigger = Auto.
Adjust C160, T106, T107, T108 and L121-L127 to obtain on the Analyzer a graph
shape similar to the second graph described in the 82 MHz filter calibration
section above.
In the event of failure, check for shorts and bad components
23.1.9
AM Mode Alignment
Note: This step should be done after successfully aligning the radio in SSB
mode
Set radio to 10,009.0 KHz, A3J, USB, ATT off, Speaker on, VOC filter in and
minimum AGC.
Attach Oscilloscope and dB meter to RX Out on J301 (sheet 3 of 6).
See test setup schematic.
Apply a 0.5 µV, 10,010.0 KHz signal to the RCV In on J101 (see test setup
configuration). Check for 1 KHz signal on the oscilloscope and verify that the
S/N ratio is 15 ±5 dB.
Change the radio to 10,010.0 KHz, A3H mode. Make sure jumper on J507 is in
the AM position.
Change RF input to AM with about 50% modulation of a 1000 Hz tone.
Increase the output of the generator by 5 dB.
Adjust T301 and T302 in the AM filter and T202 for maximum audio output of
the modulating tone. Repeat the above step to reach a S/N ratio = 10 dB.