Adjustments
7-26 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
Intermodulation
To check for high power, a range of test channel frequencies are provided. The
test channels 2 to 20 can be used to check the six bands for Intermodulation
Distortion (IMD) on the 2 to 26.5 MHz PA assembly. The test channels 4 to 29
can be used to check the six bans for IMD on the 2.25 to 30 MHz PA assembly (1
to 29 if the LF option is fitted). To check each band, there is a test channel
allocated near the bottom, top and centre of each band.
To check for low power of the 27 MHz CB channels (9323 only) the 27 MHz test
channel is used to check the IMD of the PA.
Use a spectrum analyser to test the IMD.
q Ensure the Exciter output is connected to the input J2 on the PA and Filter
PCB Assembly.
q Connect a 50 Ω dummy load to the antenna output J1.
q Connect the spectrum analyser via a 47 kΩ resistor to the antenna output J1.
This provides a low level output for the spectrum analyser.
Signal
Generator
Test
Transceiver
47 k
Ω
50
Ω
Spectrum
Anal
ser
Load
Figure 7 -4: Test set up
q Select the lowest frequency in the test channel (i.e. test channel 2 for the
2 to 26.5 MHz PA).
q Connect the signal generator to provide two-tone audio (700 Hz and
2300 Hz) via the test unit to the microphone socket.
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