Sigtronics SPE-4 - Manual

SIGTRONICS “TRANSCOM” INSTALLATION AND OPERATING INSTRUCTIONS (PERMANENT)
TRANSCOM Permanent 4-way
Transcom is a voice actuated aircraft intercom with the
capability for transmitting through the aircraft radio by the mere
push of a button. It was designed for simplicity of use. Three
controls are provided on the front panel. (See Figure 1)
POWER SWITCH — Turns unit on and off. VOLUME
CONTROL — Controls the intercom volume. (The radio
volume is controlled conventionally.)
SQUELCH CONTROL — Controls the threshold of amplifier
turn-on. This control is normally used to adjust for variations in
background noise found in different aircraft. Two Microphone
Input Jacks, labeled MIKE, are provided.
They accept the standard aircraft mike plugs (i.e. carbon or
amplified dynamic microphone.)
Two Output Jacks are provided, labeled HDPH which accept
the standard .250” aircraft headphone plug.
Two jacks are provided on the panel, labeled XMIT SW which
accept the standard aircraft .206” mike plugs: found on aircraft
push-to-talk switches. These are normally not used in the
Permanent TRANSCOM, since provisions are made for hard
wiring the push-to-talk functions to the aircraft. However, they
may be used as an option with portable aircraft push-to-talk
switches. Transmitting from both positions is possible on a one-at-
a-time basis. Each position disables the other while transmitting.
OPERATING INSTRUCTIONS
After the intercom is installed per the instructions above, it is
ready for use. Figure 2 illustrates the connections between the
TRANSCOM and headsets. In addition, push-to-talk switches
are shown in Figure 2 with dashed line for reference only.
Portable push-to-talk switches may be plugged in as shown, if
it is not desired to connect the orange and yellow wires as
shown in Fig.3.
STEP 1
—
INTERCOM MODE
A. Turn the power switch on.
B. Set the volume control to a low level.
C. Adjust the squelch control clockwise until background
noise increases or the voice is heard by speaking into
mike. Rotate the squelch counterclockwise until noise
diminishes. Then make small adjustments until the voice
triggers the unit on satisfactorily. Small adjustments may
be necessary if the aircraft background noise changes
significantly, such as from idle to full power.
STEP 2— TRANSMIT MODE
When ready to transmit, depress the Transmit Switch and
your voice is automatically transmitted via the aircraft radio.
STEP 3— RADIO MONITORING
When the unit is connected as shown, radio monitoring is
automatic. The radio monitor circuit is always active, even with
the TRANSCOM Power Switch in the OFF position.
HELPFUL HINTS
Position the boom mike in close proximity to the mouth, as
is the practice with a hand held mike, for best results.
Maintain minimum acceptable volume when using TRANS-
COM
—
particularly in low noise environments.
A fuse is located within the unit and may be replaced by a
qualified person should the need arise.
The hand held mike may be left plugged into the aircraft
mike input jack and used conventionally. However, the
TRANSCOM must be switched off during transmitting. Radio
reception will continue through the headphone, even with
TRANSCOM switched off.
When transmitting the intercom is automatically switched
OFF and your voice is heard via the aircraft radio sidetone
return. In cases where there is no sidetone return, nothing will
be heard.
The push-to-talk switch circuit must have less than 5 ohms
resistance for satisfactory operation.
FIGURE 1.
SIGTRONICS TRANSCOM CONNECTION SCHEMATIC
FIGURE 2.