MODEL TFM-138 SERIES
Airborne VHF FM Transceivers
Technisonic VHF FM Airborne Transceivers
Technisonic TFM-138 series airborne VHF/FM transceivers utilize state of the art frequency synthesis
techniques to provide FM communications on every currently available channel within the VHF/FM High
Band. These radios cover the entire band from 138 to 174 MHz in 2.5 KHz increments. Data entry and
function control are via a front panel 12 button keypad. Operating frequency and other related data are
presented on a 48 character two line LED matrix display which is available in either green or red.
Technisonic FM transceivers can be operated in the Direct Entry or Simplex mode by simply keying in the
desired operating frequency, or can function without restriction on any split frequency pair within the band.
The TFM-138 features 100 preset memory positions each of which is capable of storing a receive
frequency, a transmit frequency, a separate CTCSS tone for each receive and transmit frequency and an
alpha numeric identifier for each channel. The TFM-138B features similar storage capability, but provide for
120 channels of preset memory, and offer the additional capability of allowing for DPL (Digital Private Line)
or DCS (Digitally Coded Squelch) operation. The TFM-138 and TFM-138B allows either 25 kHz wide band
or 12.5 kHz narrow band operation on any or all their preset memory channels. Data can be easily entered
into any of the preset non-volatile memory positions for both main and guard channels via the front panel
keyboard. Information stored in memory is available for instant recall by keypad entry, or by pressing the
UP or DOWN button which allows the operator to scroll through all preset channels. Technisonic FM
transceivers feature a synthesized two channel guard, receiver, a DTMF encoder for signaling during
transmit, and a scan function which will scan any or all of the frequencies stored in the preset memory
positions.
TFM-138 series transceivers are panel mounted (Dzus mounting) and are completely self contained in a 8.0
x 3.0 x 5.75 inch chassis weighing just 3.1 pounds. Front panel controls are
MAIN
for main channel
volume;
GUARD
for guard channel volume;
MON
for squelch test; a
MN/GD
switch provides for main or
guard transmitter selection; a
G1/G2
switch selects guard 1 or guard 2 receive and transmit; and a
HI/LO
switch allows for control of transmitter power output. Hi power is 10 Watts output, low power is 1 Watt
output, which is necessary to comply with Marine harbor environment rules. These transceivers offer 28
volt DC backlighting, which is controlled by the aircraft dimmer bus. Display brightness is controlled from
the front panel keypad. The small size and light weight of TFM-138 series transceivers make them ideally
suited to helicopter installations Technisonic FM transceivers are compliant with RTCA DO-160C
categories relating to Vibration, Overpressure, Humidity, Temperature and Altitude, Magnetic Effect, Power
Input, Voltage Spike, Decompression, and RF emission (including Section 21, Category Z)
Summary of Contents for TFM-138
Page 13: ...2 2 FIGURE 2 1 Operator s Switches and Controls TFM 138 F10 B software...
Page 24: ...3 2 FIGURE 3 1 Outline Drawing for Model TFM 138 Transceiver...
Page 26: ...3 4 Figure 3 2 Wiring Connections for TFM 138 Transceiver...
Page 30: ...3 8 FIGURE 3 4 Microphone and Sidetone Level Main and Guard Squelch Adjustment Access Holes...
Page 42: ...STEP SYSTEM PASS FAIL NOTES A 11...
