Technical data

VHF/AM RADIO FSG 2T
2 General Description
June 2014 FAV_D10048 13
2.3 Technical Description
Both Transmitter and Receiver use the same digital frequency synthesizer and an
accurate reference crystal. The transmit frequency is tuned simultaneously with the
Receive frequency (Simplex operation).
The single superhet Receiver offers high immunity against in-band and out-of-band RF
interference, intermodulation and cross modulation, including ICAO Annex 10 FM
immunity / intermodulation.
The automatic Receiver AM / FM noise Squelch threshold is continuously adjustable on
the front panel by the SQ knob. Full cw position of the SQ knob requires maximum
-93 dBm / 5 µV / 50 Ω to open the Squelch. Full ccw position of the SQ knob offers
maximum Receiver gain, the Squelch is always open and RX noise is continuously
audible while in RX Mode.
The transceiver can be supplied directly from any properly fused 9 – 16.1 Vdc power
source (aircraft, vehicle, etc.) with sufficient current supply capability.
As a specific FSG 2T feature, integral controls enable full transceiver operation without
any degradation even during Emergency Supply Condition between 9 Vdc and 11 Vdc.
A suitable DC regulator is required for supply from 28 Vdc-buses.
In Ultralights, Gliders, Balloons or Portables without onboard electric power generation
system, long-term operation from a 12 Vdc battery (min. 6 Ah) is appropriate.
The onboard voltage is monitored continuously. When supply voltage drops below
11 Vdc, the Supply Indication on the LC display starts flashing as a low supply warning.
Below 8.5 to 9 Vdc, the FSG 2T turns OFF itself, but will come back into operation when
the supply voltages increases / returns to more than some 10.3 Vdc. The last used
settings remain however active.
An audio low pass filter for areas using CLIMAX operation with 25 kHz channel spacing
is incorporated in the FSG 2T, to suppress multi-carrier beat audio tones.
The audio amplifier provides AF power to the speaker (4 Watts into 4 Ohms and 50 mW
into 300 Ohms for headphones).
The solid state temperature-controlled transmitter is wideband tuned from 118 to
137 MHz and delivers some 5 Watts transmitter RF carrier power.
A keyed transmitter, without or with too low microphone modulation input voltage, is
indicated RED by the status LED on the FSG 2T front panel. Detailed information
regarding TX modulation, monitoring and setting is given in § 4.2, Microphone Set-up.
In Receive Mode for Intercom purposes (Intercom selector switch), the microphone input
level enables voice activated (VOX) pilot / crew intercommunication. This allows in
Receive Mode a voice activated intercommunication (no additional accessories needed)
between pilot and crew when using the Intercom wiring harness, headsets, proper mike
input setting and sufficient speech volume.
Intercom phone audio volume can be adjusted individually by the VOL knob on the front
panel. In addition, VOX ON is optically indicated by the GREEN TX/RX Status LED on the
front panel.