Spa 400 PDF
Spa 400 PDF
Spa 400 PDF
Figure 1
is possible on a one-at-a-time basis. The transmitting mic disables all other
mics. When you are ready to talk to ATC, depress the transmit switch on your
yoke and your voice is automatically transmitted via the aircraft radio. (You will
hear your own voice when transmitting via the aircraft radio side-tone return, If
the radio does not have side-tone, then you will not hear your voice). (A minor
modification to the intercom will enable it to simulate side-tone).
III. RADIO MONITORING Radio monitoring is automatic. The radio monitor
circuit is always active; even with intercom power switch off.
IV. SOLO FLIGHTS Since the intercom is not needed during solo flights, it may
be turned off. The pilot will still hear the aircraft radio, since this circuit is always
active, and the pilot may transmit to ATC via his push-to-talk switch. (Co-pilot
position cannot transmit when intercom is off).
V. BACK-UP If a problem is suspected in the intercom, simply turn it off. You will
still receive the aircraft radio and will be able to transmit from the pilots position.
The hand mic may also be used, however, the Transcom should be turned off
and you should unplug your boom mic from the mic jack. (Leave headphone
plugged in for radio reception).
CHASSIS INSTALLATION
The Sigtronics SPA-400 has been designed to mount either horizontally or
vertically in your aircraft panel. All necessary mounting hardware has been
supplied for a 4-way installation. (A round faceplate is also available from
Sigtronics to fit a 2 1/4 round instrument hole).
HARDWARE SUPPLIED
Four Headphone Output Jacks Accept standard .250 aircraft headphone
plugs.
Four Microphone Input Jacks Accept standard .206 aircraft microphone
plugs (i.e. amplified dynamic or electret). (U93 plug compatible jacks can be
used in place of the jacks provided).
Mic Jack Insulating Washers: 4 shoulder and 4 flat.
Panel: Lettered on both sides.
Control Knobs (2), Switch Nut (1), 4-40 Screws (2)
Template: Hole size pattern for drilling aircraft panel.
Aircraft / Intercom interface cable (4 feet long)
The location selected requires a minimum front panel area of 2-1/2 by
1-1/16. Depth required behind panel is 4-3/16 plus cable access.
Caution: Move aircraft flight controls through limits of travel while observing
selected area to make sure rear of intercom and cable will not interfere with
aircraft control components.
PANEL PREPARATION:
1. Position adhesive template on aircraft panel in selected area.
2. Center punch each hole at cross lines. (The five holes are in straight line and
equally spaced 0.4 apart.)
3. Drill 1/8 pilot hole all five places.
4. Enlarge holes to 1/4 and 3/8 per template.
Sigtronics Corporation
178 East Arrow Highway
San Dimas, CA 91773
Phone: (909) 305-9399
E-mail: info@sigtronics.com
Web Site: www.sigtronics.com
AIRCRAFT
PANEL
Figure 2
Microphone Jack
Figure 3
TIP
POINT A
TO AIRCRAFT
POWER BUSS
12 / 28 VDC
AIRCRAFT
HEADPHONE
JACK
( INTERCOM
CENTRAL
GROUND
POINT )
(7) RED
(4) BLACK
INTERCOM
CIRCUIT
BREAKER
( 1 AMP )
PILOT
HEADPHONE JACK
RING
TIP
TIP
AIRCRAFT RADIO
12345
TO A
PILOT
PTT SWITCH
BARREL
PILOT
MIC JACK
(3) BLUE
CO-PILOT
PTT SWITCH
TO A
TO A
J1
INTERCOM
TIP
RING
BARREL
P1
MIC AUDIO
(6) BROWN
SPA-400
SPA-400
INTERCOM
(5) WHITE
(2) WHITE / RED
(10) WHITE / BLUE
AN
(9) T
(8) TAN
(3) BLUE
TIP
RING
BARREL
HEADPHONE
JACK
TIP
MIC
JACK
BARREL
TO A
TO A
TIP
RING
BARREL
HEADPHONE
JACK
PASSENGER 2
TIP
MIC
JACK
TIP
BARREL
PASSENGER 1
RING
BARREL
CO-PILOT
HEADPHONE
JACK
TIP
TO A
BARREL
CO-PILOT
MIC
JACK
Figure 4
Table 1
Plug
Wire Color
Function
Pin #
White /
Pilot Mic Input
1
Black
White /
Pilot Transmit Switch Input
2
Red *A
Headphone - Radio and
Blue *B
3
Intercom Outputs
4
Black *C
Ground
White *D
Brown
Red *E
Tan *F
Tan *F
9
10
11
White /
Blue
White /
Orange
Connect To:
Ring Terminal of Pilot Intercom Mic
Input Jack
Pilot Transmit Switch (PTT) (Switch to
Ground to Transmit)
Radio Headphone Output and all
Headphone Jacks
Hand Mic Jack Ground Terminal
(Point A)
Tip Terminal of Aircraft Mic Jack or
Key Input of Aircraft Radio or Audio
Panel
Ring Terminal of Aircraft Mic Jack or
Input of Aircraft Radio
or Audio Panel
Intercom Circuit Breaker
Ring Terminal of Passenger #1 Mic
Jack
Ring Terminal of Passenger #2 Mic
Jack
12
* See Wiring Instructions
4-22-2008