Sigtronics RES-400 User Manual

Sigtronics’ STEREOCOM-400

Discover the pleasure of flying with stereo music while

maintaining VHF and passenger communications!

The STEREOCOM is a voice actuated intercom that allows pilot co­pilot and two passengers to intercom, listen to their stereo, yet hear
the VHF radio. The pilot and co-pilot can also transmit using push-to­talk switches through the VHF radio to ATC. The music is
automatically interrupted when the VHF radio is active (transmit or
receive) or when talking on the intercom. The passengers may listen
to music only; music interrupted by VHF and intercom; or VHF and
intercom only. (See Mode Selection Table for various operating
modes.)

CONFIGURATION: The Stereocom is configured in two sections:
An SPA-400 intercom with transmit capability, and an RES-400
Stereo Switcher. Both units may be installed at the same time, or the
switcher section may be easily added to an existing SPA-400
Transcom installation. The SPA-400 unit is in a 1 x 2.5’ x 4 deep
panel mount chassis, which can be mounted either in a horizontal or
vertical position. Weight: 4.5 oz. The RES-400 unit is in a 4 x 2.9’ x 2
chassis that is to be mounted remotely. Weight: 7.5 oz. All stereo
headphone jacks, mike jacks, switches, controls, harness and
connectors are supplied. Power: Stereocom operates 10 through 34
VDC without switching or adapters.

Intercom Panel Controls:

Power Switch — Turns intercom on and off.
Volume Control — Controls intercom volume, only.
Squelch Control — Controls the threshold of intercom amplifier

turn-on. It is used to adjust for variations in background noise
found in various aircraft.

Switcher Panel Controls:

Music Switch — Turns switcher on or off.
Mode Selection Switch — Four modes of operation are

possible with Stereocom using the Music On/Off and Pilot/All
switch. These are described in detail in the Mode Selection
Table. In general, the modes allow the passengers to listen to
uninterrupted music or hear the VHF and intercom. The pilot’s
and co-pilot’s music is always interrupted by the VHF and
intercom to assure fail safe operation. In order to eliminate VHF
interrupt, it is necessary to turn the VHF radio volume down or
off.

HEADSETS: The Stereocom is normally supplied to accommodate
high impedance (300 to 600 ohm) stereo headsets, such as the
Sigtronics Stereo headsets.

ENTERTAINMENT SYSTEM SELECTION: See “Helpful Hints” on
back page.

178 East Arrow Highway, San Dimas, CA 91773 909-305-9399

INSTALLATION FOR COMPLETE SPA-400 pIus RES-400 SYSTEM

(If RES-400 is to be added to existing SPA-400 installation, proceed to Installation Retrofit.)

SPA-400 CHASSIS INSTALLATION

Hardware Supplied: (SPA-400, RES-400)

Four Headphone Output Jacks — Accept .250” stereo headphone
plugs.
Four Microphone Input Jacks — Accept standard .206” aircraft
microphone plugs.
Mike Jack Insulating Washers: 4 shoulders and 4 flat.
Transcom Panel: Lettered on both sides.
Control Knobs (2), Switch Nuts (3), 4-40 Screws (2)
Switcher Panel and harness
Template (Hole size pattern)
Aircraft/Intercom interface cable (4 ft. long)

Connectors for fabricating extension cable
The location selected requires a minimum front panel area of 21/2” by
1”. Depth required behind panel is 4” plus cable access.
Allow approximately 1” by 11/2” space nearby to mount the RES-400
switcher panel.

CAUTION: Move aircraft flight controls through limits of travel while

observing selected area to make certain intercom components 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 a

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.

MOUNTING CHASSIS: See Figure 1

1. Remove nut from Transcom ON-OFF switch bushing.

2. Remove knobs from VOL and SQ controls using .050 Allen wrench.

DO NOT REMOVE nuts from VOL and SQ control potentiometers.

3. Remove two 4-40 screws and remove panel from TRANSCOM

chassis.

4. Insert Transcom from rear of aircraft panel with appropriate arrow

pointing upwards.

5. Install panel and lightly thread nut on to ON-OFF switch. Nuts and

washers on VOL and SQ controls should fit inside the 3/8” diameter

holes drilled in aircraft panel.

6. Install two 4-40 screws through holes in Transcom panel. Tighten

ON-OFF switch nut.

7. Install knobs on VOL and SQ control shafts.

MOUNTING HEADPHONE AND MICROPHONE JACKS

1. Locate mounting areas. (One mike and one headphone jack for

each headset.)

2. Drill 3/8” diameter holes for headphone jacks and install.

3. Drill 1/2” diameter holes for mike jacks and install with insulating

washers supplied. (See Figure 2)

4. Terminals on the stereo phone jacks may be identified per the mike

jack shown in Figure 2. The phone jack bushings (sleeve terminal)

must be grounded to airframe or wired to aircraft ground.

INSTALLATION RETROFIT

If the Transcom SPA-400 has been previously installed, the RES-400
Switcher may be added as follows:

1. Mount the RES-400 chassis per paragraph “RES-400 Switcher
Chassis Installation”

2. Install the Music and Mode Switches and route the harness per
paragraph “Switcher Harness Installation”.

3. Unplug SPA-400 from its wiring harness and insert Connectors J1
and P2 on the RES-400 as shown in Figure 3. Connect remaining
plugs per Figure 3.

4. Remove the headphone jacks from the pilot, co-pilot, and passenger

1. As in mounting the intercom, select a mounting location which will

RES-400 SWITCHER CHASSIS INSTALLATION

not cause interference with flight controls. (If space allows, mounting
of the Switcher within a few inches of the intercom will allow
connectors J1 and P1 to be mated directly. Otherwise, an extension
cable may be fabricated, from the connectors provided, to permit
mounting the switcher chassis elsewhere.

2. Remove the four corner panel screws and remove unit from case.

3. Drill aircraft with same hole pattern as in the switcher case. Use a
#27 drill. (Clearance drill for 6/32”)

4. Secure case to aircraft with screw heads inside switcher case for

circuit board clearance. (Care should be taken not to crush
grommets while applying torque to screws.)

5. Replace unit in the case and secure.

SWITCHER HARNESS INSTALLATION

1. Select area on panel and drill ¼” diameter holes for Music (On/Off)
and Mode (Pilot/All) Switches.

2. Mount switches with bushing key slots down.

3. Route harness to Switcher to clear aircraft controls and secure with
suitable ties.

positions in aircraft. Wires which had been connected to the phone
jacks should be cut, insulated and tied back. If two or more wires
appear on a single jack terminal, they should be cut free of the jack,
then spliced together before insulating and tying back. Do Not Dis-

turb Microphone Jacks.

5. Replace headphone jacks with three-terminal type “stereo” jacks
supplied with the RES-400 switcher. Connect wires to the stereo
jacks per Figure 3. Terminals on the stereo phone jacks may be
identified per the mike jack shown in Figure 2. The jack bushings
(barrel terminal) must be grounded to the airframe or wired to
aircraft ground.