Transmitter selector switch (audio
control panel) - #1 or #2.
Off-volume control - Turn clockwise,
set volume as required.
Frequency selector - Set desired
Fly aircraft to a point 40 nautical
miles away from test station.
At 40 nautical miles, maintain
communication with test station
while flying a 360° flat turn
(not to exceed 5
Communication should be uniformly
loud and clear through these tests.
Repeat procedure for frequencies in
low, middle, and high ranges.
HF radio set - Check as follows
Transmitter selector switch
(audio control panel) - #4.
Mode selector (HF control
panel) - Set desired operating
Microphone switch - Press
momentarily and wait for
antenna coupler to tune. A
1000 Hz tone will be heard
in the headphones until tuning
is complete. Tuning time
should not exceed 30 seconds