D.
Tuning to Channel Frequencies (Cont’d)
3.
Adjustment of Crystal Frequencies
(a) Adjust the speech clarifier control so the arrow points directly up (toward top of front
panel).
(b) Turn the power on and measure the frequency at the RX H.F.O. test jack (on main
printed circuit board). Use a coupling capacitor between the test jack and the counter
of not greater than 10 pF capacity.
(c) Adjust the RX crystal trimmer screw of the channel being tuned until the counter
reads the crystal frequency stamped on top of the crystal case.
(d) Transfer the counter test probe to the TX H.F.O. test jack using the same coupling
capacitor.
(e) Press the P.T.T. button on the microphone and adjust the TX crystal trimmer screw of
the channel being tuned until the TX crystals are on their correct frequencies.
4.
Receiver Tuning to Channel Frequencies
(a) Connect the signal generator to the ANT-GND terminals, and the audio metre across
the speaker terminals.
(b) Inject an unmodulated R.F. signal of the channel frequency desired, at a level of 0.1
Volt.
(c) With the volume turned midway CW tune the signal generator carefully until an audio
note of about 1000 Hz is heard.
(d) Reduce the level of the signal generator until the audio voltage across the speaker is
about 1 Volt.
(e) Tune the slugs of the receiver channel filter being tuned from the ‘all out’ position
(slugs flush with top of coil can) until an increase in sensitivity is noted.
