Sigtronics SAS-640 - Manual (Page 6)

When all are silent release the “SQ” button. The intercom
will immediately go quiet. In approximately one second
the intercom will briefly pop on. This tells you the squelch
has finished automatically setting. If someone did speak
while the intercom was setting, it will have to be set again.
This is because the intercom would have tried to set to
a level just above the persons voice level instead of just
above the aircraft background noise level.
Once set, the intercom stays silent until someone speaks
in their headset microphone (mic). Then it instantly turns
on and relays the conversation. After about a second of no
conversation the intercom goes silent again.
In most aircraft the squelch level wont need to be set again
until the next flight. In some high noise aircraft it is better to
set the squelch during climb or cruise.
HOT MIC MODE
When the SAS intercom turns on, it automatically comes
up in “hot mic” mode (non voice activated mode). During a
flight, if you want to deactivate the voice activated mode and
return to hot mic mode, simply turn the OFF/ALL/ISO switch
to “OFF” and wait 3 seconds and then turn it back to “ALL”
or “ISO”. To facilitate automatic setting of the squelch level,
whenever the “SQ” button is held down, the intercom also
goes into hot mic mode.
RADIO TRANSMIT MODE
When the SAS is in the “ALL” mode, transmitting from both
pilot and co-pilot positions is possible on a one-at-a-time
basis. As normal, the pilot selects the appropriate radio he
wishes to use. When the pilot presses his PTT switch, his
headset mic is automatically routed through the intercom
to the radio. Only his mic will be live. The microphones
of the co-pilot and any passengers, will be muted when
the pilot transmits. Similarly in the “ALL” mode, when the
co-pilot transmits, only the co-pilots mic will go out on the
radio. When transmitting, the pilots will hear their own voice
via the aircraft radio sidetone return. (If the radio does
not provide transmit sidetone, then you will not hear your
voice. A minor modification to the SAS unit will enable it to
simulate sidetone. (See “SAS-440 / SAS-640 SIDETONE
MODIFICATION” on page 4)
When the SAS is set to the “ISO” mode, only the pilot can
transmit and receive on the aircraft radio(s). The pilot will
not hear intercom and cannot talk to the other headsets.
The co-pilot and passengers still have intercom, but do not
hear the radios.
SOLO FLIGHTS
Since the intercom is not needed during solo flights, it may
be turned “OFF”. The pilot will still hear the aircraft radio(s),
since this circuit is always active, and may transmit to ATC
via his headset and push-to-talk switch.
FAIL-SAFE
If power to the SAS unit fails, the pilot can still transmit and
receive on the a/c radio(s) (assuming the radio(s) are still
functioning). Additionally, if a problem is ever suspected in
the intercom, simply turn it to “OFF”. In this mode you will
also be able to transmit and receive on the aircraft radio(s)
from the pilot’s position. The hand mic may also be used,
however, the SAS unit should be turned to “OFF” and you
should unplug your headset mic plug from the mic jack.
(Leave headphone plug in for radio reception).
Sigtronics Corporation
178 East Arrow Highway
San Dimas, CA 91773
Phone: (909) 305-9399
E-mail: [email protected]
Web Site: www.sigtronics.com
2-15-2007 sasinstl.pdf
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