11
TRANSMIT MICROPHONE GAIN ADJUSTMENTS
Transmit microphone gain adjustments for both the FM and the aircraft
radios are provided through two small holes on the top of the SPCC
unit. These adjustments set the microphone audio level going to the
radios during transmit. Adjustment should be made only if the
outgoing radio transmissions are reported as weak or garbled. The
Aircraft Radio Mic Gain Adjustment is set at the factory for standard
aircraft radios and should not need any adjustment. The FM Radio Mic
Gain Adjustment, however, will more than likely need to be initially
set to your particular FM radio. This level, once set, should never
need adjustment again unless, of course, the type of FM radio used is
changed. The following simple procedures take you through the
adjustment of the FM and A/C mic gain levels. If desired, a qualified
radio technician can do this for you.
FM Radio Mic Gain Adjustment can be made through the hole to the
right of the FM radio interface connector with a small, flat bladed
screwdriver. The basic adjustment concept is simple. You will be
setting the level and clarity of outgoing transmissions of the FM
radio, when it is hooked up through the SPCC, to match or exceed that
of transmissions on the radio when it is not connected to the SPCC.
To do this, you will need to transmit and receive on the FM radio to
a remote station. Arrange to have someone nearby with a radio
compatible to the FM radio you are using with the SPCC. Then . . .
Step 1 - Set the ON/BYPASS switch to the "BYPASS" position and
connect the SPCC up to power, as normal. Plug in the
observer's PTT switch and headset. Do not connect the
FM radio to the SPCC at this time. (It is not necessary
to connect the A/C radios or the pilot's headset or PTT
switch for this adjustment.) Set the observer's XMIT
SELECT switch to "FM", the AUTO/OFF/BOTH switch to
"AUTO", and the AUX switch to "OFF".
Step 2 - Set the SPCC aside for a moment. With the FM radio
disconnected from the SPCC, transmit as normal, on the
FM radio, to the remote station. Transmit long enough
so that the receiving station can get "calibrated" to
your transmission (voice) level.
Step 3 - Connect the FM radio to the SPCC as normal with the FM
interface cable. Put on the observer's headset and turn
the SPCC "ON". Verify FM radio reception. If OK, use
observer's PTT to transmit to your receiving party. If
receiving station reports weak transmission, use the
screwdriver to turn the FM MIKE GAIN ADJ clockwise a
small amount. If they report garbled or broken
transmissions, turn the FM MIKE GAIN ADJ
counterclockwise a small amount. Repeat as necessary
until the receiving party reports that transmissions
through the SPCC sound as good or better then when the
FM radio is used separate from the SPCC. That's all
there is to it!
Summary of Contents for SPCC-2
Page 5: ...3 FIGURE 1 ...
Page 7: ...5 NOTES ...
Page 16: ...14 FIGURE 3 FIGURE 4 FIGURE 5 SPCC SPECIFICATIONS ...
