User Manual

A-3
B. Determine if the image frequency for the VHF Comm falls within the range of the TFM-138
series unit. If so, select a set of frequencies that will cause the TFM-138 series unit to be
set as close as possible to the image frequency. Any one of the many possible sets will
suffice. Record those values in the spaces provided in the following chart. Modulate the
TFM-138 series transmitter on the following frequencies for at least 20 seconds. Listen for
any noise or detected audio signals on the VHF comm.
Example - Bendix/King KY 196A:
The first IF frequency is 11.4 MHZ. The L.O. is above the received frequency (high side
injection), therefore the image frequency is 22.8 MHZ above the selected frequency. Set
the KY 196A to 120.000 MHZ and the TFM-138 series Transceiver to 142.8000 MHZ.
FREQUENCIES RESULTS
VHF #1 TFM-138 series PASS FAIL
135.975 138.0000
121.150 157.5000
131.250 157.5000
Image:
FREQUENCIES RESULTS
VHF #2 TFM-138 series PASS FAIL
135.975 138.0000
121.150 157.5000
131.250 157.5000
Image:
NOTES: