Sigtronics SPCC-2 User Manual

Sigtronics SPCC-2 Communication Controllers

OPERATING INSTRUCTIONS

Models SPCC-2, SPCC-2+2, and SPCC-2+2T

INTRODUCTION

The Sigtronics Portable Communications Controller
(SPCC) provides a pilot/observer “mission team”
with the ability to transmit and receive on multiple
transceivers simultaneously; talk to each other via a
voice activated (VOX) intercom; and monitor a third
audio source. All these features, plus its portability,
make it ideal for the airborne or the ground mission
team!

Typical Radio Configurations: Use with your
aircraft radios (permanently installed or hand­held models) and an additional “FM” transceiver. A
typical “FM” radio transceiver would be: business
band, police, ham, CB, flight phone, hand-held
aircraft, marine, etc. (Some of these are actually
AM radios, however they can be used).

Dual Audio Panel capability allows each headset
position to select which radios to transmit and

receive on - independent of the other headset. Each
headset position has dual volume controls, one for
radio reception, and the other for their intercom
volume level.

Voice Activated Intercom feature allows “hands­free” communication between headsets connected
to the SPCC. Start speaking and the intercom
instantly turns on to relay your message clearly to
the other headset. Stop talking and it turns off to
reduce background noise.

Auxiliary Input lets you monitor a third audio
source, such as a police scanner, music source, etc.

Portable design gives flexibility and eliminates
expensive installation costs. Especially useful
to small departments that rent or lease. Or if a
scheduled aircraft is down, the SPCC can be used
in an alternate aircraft.

igtronics

S

®

Specialists in “SOUND” Management

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

TECHNICAL HIGHLIGHTS which make the SPCC
unbeatable are:

Fail-Safe Bypass Switch allows the pilot to operate
the aircraft radios even if the unit is turned off.

Automatic Sidetone Generation lets the pilot and
copilot hear what the other is transmitting over the
radios.

Separate Transmitter Microphone Gain
Adjustments adjust the aircraft radio and the FM

radio.

Excellent RF Immunity guarantees clean, clear
transmissions.

Power Requirements: A standard cigarette lighter
socket (11 to 34 VDC) or a battery pack.

Standardized to general aviation headsets and
portable push-to-talk switches. (The unit can also
be wired into permanently installed PTT switches).
Helicopter headsets will also work with the unit if
headset plug adapters are used.

APPLICATIONS

CONTROL FUNCTIONS

ON / BYPASS - Power Switch - In “ON” position;

supplies power to all SPCC circuits. In “BYPASS”
position; disables all unit functions, and connects
pilot directly to the aircraft radios. A fail-safe feature!

VOL - Intercom Volume - Adjusts intercom volume
level.

SQ - Intercom Squelch - Adjusts VOX operation of
the intercom for variations in headset microphones
and background noise levels.

XMIT SELECT -Transmit Select - Used to select
which radio to transmit on.

BOTH / OFF / AUTO - Receive Select - Used to select
which radio is heard. In “BOTH” position, you hear
both aircraft and FM radios. In “OFF” position, you
do not hear either radio. In “AUTO” position, only
the radio selected by the XMIT SELECT switch is
heard.

AUX / OFF -Auxiliary Select - Turns the auxiliary
input source on or off.

REC VOL - Receive Volume - A general control used
to set the volume level of the aircraft radio(s), FM
radio, and the auxiliary monitor input.

• Airborne Law Enforcement - Small police
departments to large organizations like the FBI.

• Civil Air Patrol/Coast Guard -Air search and
rescue operations.

• Medevac Helicopters - Medical emergency
aircraft

• Airborne Fire Control

• Forestry Departments

• Wild Life Organizations - Survey and tracking

operations

• TV News Crews

• Airborne Traffic Reporters

• Ground Operations requiring more than one

radio.

• Additional aircraft VHF radio capability -Add an
inexpensive hand-held aircraft radio as a second
radio without installation costs.

A/C RADIO MIC GAIN ADJ - Aircraft Radio
Microphone Gain Adjustment - Sets the transmit
mic audio level for the aircraft radio(s).

FM RADIO MIC GAIN ADJ - FM Radio Microphone
Gain Adjustment - Sets the transmit mic audio level
for FM radio.

SPCC INSTALLATION

The SPCC requires six simple connections to put it
into operation. The power cord, the aircraft radio,
the FM radio, the auxiliary audio input source
(optional), the push-to-talk switches, and the
headsets must all be connected for the system to
work as designed. But do not fear, Sigtronics has
simplified the connection process, so it will just
take a few moments. Refer to the SPCC connection
drawing Figure 1 on page 3.

1. Power Cord: The four foot power cord with
LED Power Indicator is designed to plug directly
into a standard cigarette lighter socket. The LED
indicator will be on if power is available, it will
be off if no power or reversed socket wiring.
Note: The LED shows power available, not SPCC
On or Off. The SPCC will run on 11-34 VDC, so it

Page 2

FIGURE 1

Auxiliary

Audio

Source

* Portable

Transmit Switch

* The female jack on portable

push-to-talk switch is not used.

Aux. Audio

Input Jack

Mic Plug

Transmit Plug

Headphone Plug

Aircraft

Hand Mic

Jack

A/C Radio

Mic Adjust

AUX BOTH

OFF

AUTO REC

OFF

VOL

MIC

A/C

FM

XMIT

XMIT SW

SELEC T

HDPH

INTER COM INTER COM

SQ

Aircraft

Headphone

Jack

AUX BOTH

OFF

A/C

SPCC- 2

ON

BYPASSVOL

SQ VOL

Cigarette Lighter or

Portable Battery Pack

OFF

AUTO REC

VOL

MIC

FM

XMIT

XMIT SW

SELEC T

HDPH

LED Power

Indicator

Interface Cable

FM Radio

Interface Jack

FM Radio

Mic Adjust

Mic Plug

Transmit Plug

Headphone Plug

FM

Radio

FM Radio

* Portable

Transmit Switch

automatically adjusts to 12 or 24 volt aircraft. The
SPCC can also be powered by an auxiliary battery
pack, if desired.

2. Aircraft Radio: The mic and headphone cords
on the unit are designed to plug into the mic
and headphone jacks in the panel of the aircraft.
If the aircraft does not have either one of these
jacks, they can be installed by any qualified
avionics technician. If you plan to use the SPCC in
a helicopter, please contact Sigtronics for advise
on adapting the general aviation plugs to the
helicopter jacks.

3. FM Radio: An interface cable is needed to
connect the SPCC to the FM radio. On one end
of the cable will be a five pin connector to plug
into the jack on the top of the SPCC. On the other
end will be whatever is required by your FM radio.
Since virtually any radio can be used and there
is little standardization among manufacturers,
no one cable will work for all radio transceivers.
Therefore, the FM radio interface cable will have
to be fabricated for your particular radio. This
cable can be supplied to you by Sigtronics or
made up by your radio technician. If you decide to

purchase a completed interface cable, Sigtronics
has an extensive cable making facility and can
provide you with one at minimum cost. We will
need to know what length cable you require and
the manufacturer and model number of the radio
you wish to use.

If you would rather have your radio technician

make the cable, the FM radio interface cable
connector pin assignments and some typical
cable wiring examples are located on page 7. A
five pin connector plug is supplied with each SPCC
unit for this purpose. You will also need the radio
mating connector and connection schematic or
hook-up drawing for your particular FM radio.
These can usually be obtained from the radio
manufacturer.

4. Auxiliary Radio: If you are using an auxiliary
radio, then a simple interface cable is also needed
to connect the SPCC to the auxiliary audio
input source. The SPCC accepts a standard 1/8”
monaural mini plug.

5. Push-to-Talk Switches: In order for pilot and
observer to transmit on their selected radios,
they will each need a push-to-talk (PTT) switch.

Page 3

The SPCC is compatible with all standard general
aviation type portable push-to-talk switches. The
male plug on the PTT switches plug directly into
the XMIT SW jacks of the SPCC unit. If your PTT
switches also have a female jack, it is not used. The
pilot should strap the switch end of his portable
PTT switch to the yoke or stick of the aircraft.
The observer’s PTT can similarly be strapped to
the co-pilot controls or operated as a hand-held
switch. Various types of push-to-talk switches are
available from Sigtronics, including one that does
not have the female jack.

If you already have permanently wired push-to-

talk switches in the aircraft, and wish to use them
with the SPCC instead of the portable type, then
wiring modifications will have to be made to the
aircraft. Again, your avionics technician should be
able to do this for you.

6. Headset Hookup: All standard general aviation
headsets are compatible with the SPCC unit.
Helicopter type headsets can also be used if
adapter cables are used. (Sigtronics manufactures
cables that adapt the helicopter plugs to general
aviation plugs).

Plug the microphone and headphone plugs

on the headsets into the jacks labeled MIC and
HDPH, on the front panel of the SPCC. Put on
the headset, and position the boom mic close
to the mouth, as is the practice with hand-held
microphones. Voice clarity is best when the mic
is about 1/4” away and slightly off center from the
lips. Turn headset volume control(s), if any, all the
way up.

INITIAL SYSTEM CHECK-OUT

The following System Check-Out will provide you
with a “personalized” system. Perform the next
few steps while on the ground to assure that all
functions on the unit and radios are set to your
personal hearing and speaking comfort.

CAUTION - As is standard practice with all aircraft
equipment, be sure that the radio(s) and the SPCC
are turned OFF when you start up the aircraft
engine.

1. To assure that the aircraft radios, and pilot’s
headset and PTT switch are connected and
functioning properly, put ON/BYPASS switch
into “BYPASS” position. Then turn on the aircraft

radios, and verify that the pilot can hear the radios
and can transmit using his push-to-talk switch
and headset. All other intercom functions should
be inoperable in the BYPASS mode.

2. Intercom operation and adjustment can be
performed by the following procedure:

A. First set the ON/BYPASS switch to the “ON”

position and turn both REC VOL controls all the
way down (counterclockwise).

B. Turn both intercom volume controls to the 9

o’clock position and both squelch controls all
the way up (clockwise). Notice the intercom is
now continually activated and you should be
able to talk between headsets.

C. To adjust the intercom squelch controls for voice

activated operation (VOX), it is helpful to have
some background noise present. It may also
be necessary to turn up the intercom volume
controls. Turn both intercom squelch controls
all the way counterclockwise. Now, without
speaking, rotate one of the squelch controls
clockwise until you hear the background
noise in your headset. Next, using that same
control, rotate counterclockwise small,
incremental amounts until the background
noise disappears. (This procedure is necessary
because the squelch is a “fast on, slow off”
system). That squelch control is now set.

D. Adjust the other intercom squelch control

similarly by turning it clockwise until you hear
background noise. Rotate counterclockwise
incremental amounts until the background
noise disappears.

Small adjustments may be necessary if aircraft

background noise changes significantly - such
as from idle to full power.

3. Radio Selection of both the aircraft and the FM
radios is provided by two switches.

A. XMIT SELECT determines the radio you wish to

transmit on.

B. AUTO/OFF/BOTH selects which radios you

receive in your headset.

i. “AUTO” position allows you to hear the radio

that the XMIT SELECT switch is set to.

ii. “OFF” prevents you from hearing either

radio.

Page 4

iii. “BOTH” position permits you to hear both

the aircraft radio(s) and the FM radio at the
same time.

4. The AUXliary audio source is selected by the AUX/
OFF switch. In the “AUX” position, you can hear it,
and in the “OFF” position you cannot.

5. Receive Volume Controls (REC VOL) are general
volume controls, meant to provide overall
listening level for all three radios simultaneously

- A/C, FM, and AUX. Finite volume adjustments of
any individual radio should be done by altering
the radio volume control at the radio itself.

SYSTEM OPERATION

Once the radios are selected, pilot or observer can
transmit at any time simply by pressing their PTT
switch. When one position transmits, several things
take place automatically to the transmitting side of
the SPCC:

• The intercom between the two positions is turned
off.

• The Auxiliary audio, if selected, is muted.

• The receive audio of the radio not selected by the
XMIT SELECT switch is muted, regardless of the
position of the AUTO/OFF/BOTH switch.

• The selected radio is put into transmit mode.

• The headset microphone audio (your voice) is
sent to the selected transmitter.

• Sidetone is generated and sent to your
headphones.*

* Sidetone is a portion of the transmitted voice
signal sent back into your headset, so that you can
hear what you are saying while transmitting. The
RECeive VOLume control adjusts the volume level
of the sidetone that you hear in your headset. If the
AUTO/OFF/BOTH switch is in the “OFF” position
however, you will not hear this sidetone.

The non-transmitting side is not affected (except for
intercom) when the other side transmits. The non­transmitting side can monitor the transmissions of
the other side by simply selecting the same radio on
his side of the SPCC. Of course, when the PTT switch
is released, (stop transmitting) all functions return
to normal, instantly and automatically.

Simultaneous Transmit is the most attractive
and powerful feature of the SPCC. Both pilot and

observer can transmit at the same time - either on
separate radios or on the same radio transmitter!
When on different radios, the pilot and observer
will not interfere with each other’s communications.
For example, the pilot can talk to air traffic control
while the observer talks on the FM radio to the
ground crew, or vice versa. On the other hand, they
can also transmit on the same radio transmitter. If,
for example, the observer is talking on one of the
radios, the pilot can jump right in and add to the
conversation simply by pressing his PTT switch.
Both voices will be heard by the receiving station.

NOTE: Only the aircraft radios and the FM radio
can be transmitted on. The AUXiliary input is for
listening only. It can be used for listening to a police
scanner, monitoring the audio portion of a video
camera, listening to background music, and many
other possibilities.

TRANSMIT MICROPHONE GAIN ADJUSTMENTS

Transmit microphone gain adjustments for both
the FM and the aircraft radios are provided through
two small holes on the top of the SPCC unit. These
adjustments set the microphone audio level going
to the radios during transmit. Adjustment should be
made only if the outgoing radio transmissions are
reported as weak or garbled. The Aircraft Radio Mic
Gain Adjustment is set at the factory for standard
aircraft radios and should not need any adjustment.
The FM Radio Mic Gain Adjustment, however, will
more than likely need to be initially set to your
particular FM radio. This level, once set, should never
need adjustment again unless, of course, the type
of FM radio used is changed. The following simple
procedures take you through the adjustment of the
FM and A/C mic gain levels. If desired, a qualified
radio technician can do this for you.

FM Radio Mic Gain Adjustment can be made
through the hole to the right of the FM radio
interface connector with a small, flat bladed
screwdriver. The basic adjustment concept is
simple. You will be setting the level and clarity of
outgoing transmissions of the FM radio, when it is
hooked up through the SPCC, to match or exceed
that of transmissions on the radio when it is not
connected to the SPCC. To do this, you will need to
transmit and receive on the FM radio to a remote
station. Arrange to have someone nearby with a

Page 5

radio compatible to the FM radio you are using
with the SPCC. Then . . .

1. Set the ON/BYPASS switch to the “BYPASS”
position and connect the SPCC up to power, as
normal. Plug in the observer’s PTT switch and
headset. Do not connect the FM radio to the SPCC
at this time. (It is not necessary to connect the
A/C radios or the pilot’s headset or PTT switch for
this adjustment.) Set the observer’s XMIT SELECT
switch to “FM”, the AUTO/OFF/BOTH switch to
“AUTO”, and the AUX switch to “OFF”.

2. Set the SPCC aside for a moment. With the FM
radio disconnected from the SPCC, transmit as
normal, on the FM radio, to the remote station.
Transmit long enough so that the receiving
station can get “calibrated” to your transmission
(voice) level.

3. Connect the FM radio to the SPCC as normal with
the FM interface cable. Put on the observer’s
headset and turn the SPCC “ON”. Verify FM radio
reception. If OK, use observer’s PTT to transmit to
your receiving party. If receiving station reports
weak transmission, use the screwdriver to turn the
FM MIKE GAIN ADJ clockwise a small amount. If
they report garbled or broken transmissions, turn
the FM MIKE GAIN ADJ counterclockwise a small
amount. Repeat as necessary until the receiving
party reports that transmissions through the SPCC
sound as good or better then when the FM radio
is used separate from the SPCC. That’s all there is
to it!

1. Set the ON/BYPASS switch to the “BYPASS”
position and connect the unit as normal to power
and aircraft radios. Plug in the pilot’s headset and
PTT switch into the jacks on the left side of the
SPCC. (The FM radio and observer’s headsets and
PTT switches are not needed for this adjustment.)
On the pilot’s side of the SPCC, set the XMIT

SELECT switch to the “A/C” position, the AUTO/
OFF/BOTH switch to “AUTO”, and the AUX/OFF

switch to “OFF”.

2. Put on the pilot’s headset. Transmit and receive to
your nearby station, using the pilot’s PTT switch
and headset, as described in the Initial System
Check-Out section on page 8. Verify good
transmission and reception. In this mode you are
bypassing the SPCC and verifying the clarity of the
aircraft radios.

3. If radios check out OK, then turn the ON/BYPASS
switch to the “ON” position. Verify aircraft radio
reception. If OK, use the pilot’s PTT to transmit
to your receiving party. If the receiving station
reports weak transmissions, use the screwdriver
to turn the A/C MIKE GAIN ADJ clockwise a
small amount. If they report garbled or broken
transmissions, turn the A/C MIKE GAIN ADJ
counterclockwise a small amount. Repeat as
necessary until the receiving party reports that
transmissions with the SPCC turned “ON” sound
as good as that when the ON/BYPASS switch is
“BYPASS” mode.

The A/C Radio Mic Gain Adjustment is located to
the left of the FM radio interface connector. Again,
the A/C Mic Gain Adjustment, in most cases, will not
have to be changed from its original factory setting.
If however, your aircraft radio transmissions through
the SPCC are reported as weak or garbled, you will
need to reset this level. The adjustment procedure
is similar to that of the FM mic gain adjustment
above. You can, however, use the “BYPASS” mode
of the SPCC to aid in the adjustment. Arrange to
have someone with an aircraft radio nearby with
whom you can transmit and receive. Then, proceed
as follows:

Page 6

FM RADIO INTERFACE CABLE WIRING

FM Radio Interface Cable Connector

Pin Assignment

FIGURE 2

Male five pin connector shown from solder side:

Pin Function

1 Mic audio output to FM radio

3 Receive audio input from FM radio

4 FM radio ground

Transmit key output to FM radio (Normally

2,5

open relay contacts closed during FM ra­dio transmit)

FM RADIO INTERFACE CABLE WIRING

The following are some examples of possible wiring
schemes for the FM interface cable. Only the FM
radio functions are shown for the FM radio end of
the interface cable, because the connector(s) used
by radio manufacturers varies widely. You will
have to consult the radio manual or manufacturer
for the connector(s) used and pin assignments
for your particular FM radio. Also, Sigtronics has
extensive radio interface experience and can assist
in any question you might have concerning this or
any other aspect of the SPCC. Of course, Sigtronics
can build a FM interface cable for you to your
specifications, if desired.

Figure 3 shows the most common of such cables
with its “high level mic input” and standard “ground
to key” interface. This cable will work with most
standard police, fire, and business band radios as
well as aircraft type radios.

1

PLUG END SOLDER END

3

4

5

2

FIGURE 3

SPCC
Pin #

1

2

4

3

5

FM RADIO

Mic Audio Input

Ground

Headphone Audio
Outpu t

Transmit Key Input

FIGURE 4

SPCC
Pin #

33K *

1

2

1K *

4

3

5

* Use 1/8 or 1/4 watt resistors

FM RADIO

Mic Audio Input

Ground

Headphone Audio
Outpu t

Transmit Key Input

3

5

1

4

2

Figure 4 is similar to Figure 3 but is used for radios
requiring a low level mic input such as marine type
radios.

Figure 5 shows typical cable wiring for radios that
sense the presence of mic current to transmit. Most
ICOM hand-held radios are set-up this way.

Page 7

SPCC
Pin #

1

2

3

4

5

FIGURE 5

FM RADIO

Headphone Audio
Outpu t

Ground

Transmit Key Input

THREE YEAR WARRANTY

SPCC SPECIFICATIONS

Every Sigtronics’ Product has been carefully
inspected before shipment. We guarantee to
correct any defect caused by faulty material or
workmanship free of charge to the user who
originally purchased the product per the enclosed
warranty card. Our obligation assumed under this
guarantee is limited to the replacing of any part
or parts which prove to our satisfaction, upon
examination to have been defective, and which
have not been misused or carelessly handled. The
complete unit must be returned to our factory,
transportation charges prepaid. We reserve the
right to decline responsibility where repairs or
replacements have been made or attempted by
others. No other guarantee, written or verbal, on
our products is authorized by us.

Repairs required due to abuse, misuse, damage or
normal service beyond the warranty period will be
subject to normal service charges.

Input Voltage: 11-34 VDC

Nominal Current: 0.07 Amps

Maximum Current: 0.15 Amps

Weight: 22 oz.

Size: 3.75 x 6.25 x 2.5 inches

A/C Interface Cord length: 4 feet each

SIGTRONICS CORPORATION

178 East Arrow Highway
San Dimas, CA 91773

Phone: [phone]

FAX: [phone]

Web: www.sigtronics.com

To expedite factory service work, write Sigtronics’
Service Department and explain the problem. All
correspondence relative to service work should
include model and serial number. Frequently
problems can be resolved by phone. Should you
wish to call, our number is [phone].

Page 8

8-4-2011 spcc2i&o.pdf