Sigtronics SPA-400 - Manual (Page 2)

MOUNTING CHASSIS (continued)
5. Install panel and lightly thread nut on to ON-OFF switch. Nuts and washers on
Volume and Squelch controls should fit inside the 3/8” diameter holes.
6. Select two 4-40 screws through holes in intercom panel. Tighten ON-OFF
switch nut.
7. Install knobs on Volume (VOL) and Squelch (SQ) control shafts using .050”
Allen wrench.
MOUNTING HEADPHONE AND MICROPHONE JACKS:
1. Select mounting areas. (One mic and one headphone jack for each
headset). Again, make sure the jacks will not interfere with aircraft control
components.
2. Drill 3/8” diameter holes for headphone jacks and install.
3. Drill 1/2” diameter holes for mic jacks and install with insulating washers
supplied. (See Figure 3).
WIRING INSTRUCTIONS
Connections should be made as shown in Figure 4 and indicated in Table 1
*A. White / red (pilot push-to-talk) must correspond with white / black (pilot mic
input) as shown.
*B. The blue wire from Pin 3 must be connected to the aircraft radio headphone
output- NOT the speaker output.
*C. Connect all intercom mic jack grounds to Point A as shown in Figure 4. (Use
black washers supplied to insulate intercom mic jacks from aircraft chassis
ground).
*D. Do NOT connect transmit switches to white (key) wire.
*E. Red wire may be connected to either 12 (14V) or 24 (28V) power source. No
switching or adjustments are required to operate from either source.
*F. Tan wires from Pins 8 and 9 are only used on 4-way installations.
FINAL CHECKOUT AND ADJUSTMENT
After the unit is installed, again check that the intercom chassis, jacks, and wiring
harness are clear of all aircraft operating controls and cause no interference with
them. Check out the intercom functions by following the Operating Instructions.
It may be necessary at this time to adjust the intercom mic output to the aircraft
radios. A small, square, adjustable trimmer potentiometer is provided inside
the unit for this purpose. It is accessible through a hole in the side of the case,
marked “Mod. Adj.”, and can be adjusted with a screwdriver. In the event of over
modulation (garbled) or reports of weak transmissions over the aircraft radio, an
appropriate adjustment can be made. Clockwise rotation increases the output
level to the aircraft radio mic input. Counter-clockwise rotation decreases
modulation level. This adjustment sometimes needs to be made after initial
installation of the intercom or if a new radio is installed. (The output is set for unity
gain at Sigtronics.)
Weight: Intercom with panel and knobs (4.5 oz.)
Jacks and wiring harness (5.5 oz. maximum)
Current Draw: 0.06 amps @ 28 volts
FAA TSO: C50b ENV. CAT (DO-160) CFBBBX
SPA-400
INTERCOM
CO-PILOT
HEADPHONE
JACK
CO-PILOT
MIC
JACK
PILOT
HEADPHONE JACK
AIRCRAFT
HEADPHONE
JACK
AIRCRAFT
HAND MIC
JACK
PILOT
MIC JACK
BARREL
BARREL
BARREL
BARREL
TIP
TIP
TIP TIP
TIP
TIP
RING
RING
RING
AIRCRAFT RADIO
12345
AIRCRAFT / INTERCOM INTERFACE AREA
PILOT
PTT SWITCH
CO-PILOT
PTT SWITCH
TO AIRCRAFT
POWER BUSS
12 / 28 VDC
INTERCOM
CIRCUIT
BREAKER
( 1 AMP )
(3) BLUE
(3) BLUE
(1) WHITE / BLACK
(6) BROWN
(5) WHITE
(8) TAN
(9
)T
A
N
(2) WHITE / RED
(10) WHITE / BLUE
(11) WHITE / ORANGE
(7
)R
E
D
(4
)B
LA
C
K
P1
J1
HEADPHONE AUDIO
MIC AUDIO
RADIO MIC KEY
HEADPHONE
JACK
MIC
JACK
BARREL BARREL
TIP TIP RING
PASSENGER 2
HEADPHONE
JACK
MIC
JACK
BARREL BARREL
TIP TIP RING
PASSENGER 1
TO A
TO A TO A
TO A
TO A TO A
POINT A
( INTERCOM
CENTRAL
GROUND
POINT )
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INTERCOM SPA-400
Table 1
Plug
Pin #
Wire Color Function Connect To:
1
White /
Black
Pilot Mic Input
Ring Terminal of Pilot Intercom Mic
Input Jack
2
White /
Red *A
Pilot Transmit Switch Input
Pilot Transmit Switch (PTT) (Switch to
Ground to Transmit)
3 Blue *B
Headphone - Radio and
Intercom Outputs Radio Headphone Output and all
Headphone Jacks
4 Black *C Ground
Hand Mic Jack Ground Terminal
(Point A)
5 White *D
Transmit Relay (Key)
Control Output
Tip Terminal of Aircraft Mic Jack or
Key Input of Aircraft Radio or Audio
Panel
6 Brown Mic Audio Output
Ring Terminal of Aircraft Mic Jack or
Input of Aircraft Radio
or Audio Panel
7 Red *E
12 VDC through 24 VDC
Power Input
Intercom Circuit Breaker
8 Tan *F Passenger #1 Mic Input
Ring Terminal of Passenger #1 Mic
Jack
9 Tan *F Passenger #2 Mic Input
Ring Terminal of Passenger #2 Mic
Jack
10
White /
Blue
Copilot Transmit Switch Copilot Transmit Switch (PTT)
11
White /
Orange
Copilot Mic Input
Ring Terminal of Intercom Copilot Mic
Input Jack
12 No Connection
* See Wiring Instructions
SPA-400 Installation Drawing Figure 4
spa-400.pdf 4-22-2008 Form SPA-400-IS REV H