Adjustments
7-12 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
HPF/LPF filter alignment
HPF filter
The six high-pass filters are located on the Rx/Exciter PCB [108-04962 and
08-05322]. Each filter contains an adjustable inductor in series with a capacitor to
form a series tuned circuit. You will need to set up the following before checking
the alignment of the inductors.
q Connect an audio voltmeter to the audio output (across the speaker).
q Adjust the volume control for a suitable noise reference point on the audio
meter (about ¼ scale).
q Connect a signal generator to the receiver input.
©
It is important that the signal generator output level is always kept below the
AGC threshold to ensure the optimum tuning point can be seen on the audio
meter.
Checking the alignment of the inductors in Test mode
q Select the required test, signal generator frequency and the inductor number
from the list for test numbers below.
Test Signal generator frequency Inductor
6 1.40 MHz
1.401 MHz ±100 Hz
L19
7 2.18 MHz
2.181 MHz ±100 Hz
L16
8 3.48 MHz
3.481 MHz ±100 Hz
L13
9 5.30 MHz
5.301 MHz ±100 Hz
L10
10 8.26 MHz
8.261 MHz ±100 Hz
L7
11 12.6 MHz
12.601 MHz ±100 Hz
L4
©
Test 6, L19 is adjusted with link 1.6 removed. Link 1.6 to be refitted after
adjustment if used with 1.6 to 30 MHz PA assembly [108-05237].
q Set the signal generator frequency to the correct frequency according to the
list above.
q Adjust the output level for approximately +10 dB above the noise level
indicated on the audio meter (1 kHz tone should be heard in the speaker).
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