Sigtronics SAS-640 User Manual

Page 3

4. Install insulating washers as necessary if the barrel of the

mic jack is mounted in metal.

For the headphone jack, just add the blue wire (pin 3) to

the tip terminal. No need to remove existing wires on the

headphone jack.

WIRING INSTRUCTIONS

Connections should be made as shown in Figure 4 and

indicated in Table 1. If longer wire lengths are required, use

a good quality hook-up wire - 22 gauge or larger. Although

not necessary, shielded audio wire can be used if desired.

This can simplify the wiring process.
*1. The blue wire from Pin 3 must be connected to the aircraft

radio headphone output - NOT the speaker output.

*2. Connect all intercom mic jack grounds to a single aircraft

chassis ground point - Point “A” - as shown in Figure

4. (Use the black washers supplied to insulate the

intercom mic jacks from aircraft chassis ground). Note

this intercom central grounding point is used to eliminate

any unwanted electrical noises, such as alternator whine

or strobe noise, from being induced into the intercom

system through the grounds. All intercom mic jack barrels

must be insulated from ground where they are mounted

and connected back to Point “A” on their own individual

ground wire. Similarly, both intercom ground wires (pin

4) and the push-to- talk switch grounds must also be

connected back to Point “A”. It is not necessary, however,

to connect the headphone jack barrels to Point “A”. They

can either be grounded where they are mounted or some

place nearby.

*3. The red wire may be connected to either 12V (14V) or

24V (28V) power source. No switching or adjustments

are required to operate from either source.

*4. Tan wires (pins 8 and 9) are only used on installations

that require extra intercom positions.

*5. Provided on SAS-640 units only.
Skip down to the INSTALLATION CHECK OUT AND

ADJUSTMENTS section on page 4.

��

� ��

��

�

��

�

��

��
��

��

��
��

��

�

��

�

��

�

��

��
��

��
��
��
��

��

�

��

�

��

�

��

TABLE 1 – See Wiring Instructions

PIN

WIRE COLOR

FUNCTION

CONNECT TO

White / Black

Pilot Mic Input

Ring Terminal of Pilot Mic Jack

White / Red

Pilot and Radio Transmit

Switch Input

Pilot Transmit Switch (PTT) & Radio

Key Input (Switch to Ground to

Transmit)

Blue *1

Pilot Headphone - Radio &

Intercom Outputs

Radio Headphone Output and Tip

Terminal of Pilot Headphone Jack

Black *2

Intercom Central Grounding

Point “A”

Aircraft Chassis Ground

N/C

None

No Connection

Brown

Transmit Mic Audio Output

Ring Terminal of Aircraft Hand Mic

Jack or Mic Input of Aircraft Radio

or Audio Panel

Red *3

12 through 24 VDC Power

Input

Intercom Circuit Breaker

Tan *4

Passenger #1 Mic Input

Ring Terminal of Passenger #1

Intercom Mic Jack

Tan *4

Passenger #2 Mic Input

Ring Terminal of Passenger #2

Intercom Mic Jack

10 White / Blue

Co-Pilot Radio Transmit

Switch Input

Co-Pilot Transmit Switch (PTT)

(Switch to Ground to Transmit)

White / Orange Co-Pilot Mic Input

Ring Terminal of Co-Pilot Intercom

Mic Jack

12 White / Green

Co-Pilot & Passenger

Intercom Headphone Output

Tip Terminal of Co-Pilot &

Passenger Headphone Jacks

13 Tan *5

Passenger #3 Mic Input

Ring Terminal of Passenger #3

Intercom Mic Jack

14 Tan *5

Passenger #4 Mic Input

Ring Terminal of Passenger #4

Intercom Mic Jack

This manual is related to the following products:

SAS-440