Sigtronics SPCC-2 - Manual (Page 4)

The SPCC is compatible with all standard general
aviation type portable push-to-talk switches. The
male plug on the PTT switches plug directly into
the XMIT SW jacks of the SPCC unit. If your PTT
switches also have a female jack, it is not used. The
pilot should strap the switch end of his portable
PTT switch to the yoke or stick of the aircraft.
The observer’s PTT can similarly be strapped to
the co-pilot controls or operated as a hand-held
switch. Various types of push-to-talk switches are
available from Sigtronics, including one that does
not have the female jack.
If you already have permanently wired push-to-
talk switches in the aircraft, and wish to use them
with the SPCC instead of the portable type, then
wiring modifications will have to be made to the
aircraft. Again, your avionics technician should be
able to do this for you.
6. Headset Hookup: All standard general aviation
headsets are compatible with the SPCC unit.
Helicopter type headsets can also be used if
adapter cables are used. (Sigtronics manufactures
cables that adapt the helicopter plugs to general
aviation plugs).
Plug the microphone and headphone plugs
on the headsets into the jacks labeled MIC and
HDPH, on the front panel of the SPCC. Put on
the headset, and position the boom mic close
to the mouth, as is the practice with hand-held
microphones. Voice clarity is best when the mic
is about 1/4” away and slightly off center from the
lips. Turn headset volume control(s), if any, all the
way up.
INITIAL SYSTEM CHECK-OUT
The following System Check-Out will provide you
with a “personalized” system. Perform the next
few steps while on the ground to assure that all
functions on the unit and radios are set to your
personal hearing and speaking comfort.
CAUTION - As is standard practice with all aircraft
equipment, be sure that the radio(s) and the SPCC
are turned OFF when you start up the aircraft
engine.
1. To assure that the aircraft radios, and pilot’s
headset and PTT switch are connected and
functioning properly, put ON/BYPASS switch
into “BYPASS” position. Then turn on the aircraft
radios, and verify that the pilot can hear the radios
and can transmit using his push-to-talk switch
and headset. All other intercom functions should
be inoperable in the BYPASS mode.
2. Intercom operation and adjustment can be
performed by the following procedure:
A. First set the ON/BYPASS switch to the “ON”
position and turn both REC VOL controls all the
way down (counterclockwise).
B. Turn both intercom volume controls to the 9
o’clock position and both squelch controls all
the way up (clockwise). Notice the intercom is
now continually activated and you should be
able to talk between headsets.
C. To adjust the intercom squelch controls for voice
activated operation (VOX), it is helpful to have
some background noise present. It may also
be necessary to turn up the intercom volume
controls. Turn both intercom squelch controls
all the way counterclockwise. Now, without
speaking, rotate one of the squelch controls
clockwise until you hear the background
noise in your headset. Next, using that same
control, rotate counterclockwise small,
incremental amounts until the background
noise disappears. (This procedure is necessary
because the squelch is a “fast on, slow off”
system). That squelch control is now set.
D. Adjust the other intercom squelch control
similarly by turning it clockwise until you hear
background noise. Rotate counterclockwise
incremental amounts until the background
noise disappears.
Small adjustments may be necessary if aircraft
background noise changes significantly - such
as from idle to full power.
3. Radio Selection of both the aircraft and the FM
radios is provided by two switches.
A. XMIT SELECT determines the radio you wish to
transmit on.
B. AUTO/OFF/BOTH selects which radios you
receive in your headset.
i. “AUTO” position allows you to hear the radio
that the XMIT SELECT switch is set to.
ii. “OFF” prevents you from hearing either
radio.
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