Technical data

VHF/AM RADIO FSG 2T
3 Installation
36 FAV_D10048 June 2014
3.5.2.2 Dynamic Microphone(s)
Due to the extremely wide mike input level adjustment range, it is mandatory to
understand that correctly matched FSG 2T mike input sensitivity will be good ONCE
FOREVER for this configuration. This guarantees a stable operation without audio
feedback and maximum modulation at the best background noise attenuation.
IMPORTANT!
 NEVER use a 3-pole mike jack type PJ-068 for non-amplified dynamic
microphones because common ground is used both for mike and for PTT.
This creates a ground loop and causes unstable / distorted modulation.
 Dynamic (non-amplified) microphones connected to a Standard Carbon
MIC input will not work on that input!
 Dynamic MIC input range = 0.5 mV … 15 mV.
The FSG 2T default input for dynamic microphone(s) is pin 1 of the Standard DB-15
receptacle.
Our pre-wired cable harness assemblies are color coded for simple plug-in
installations when used with optional Loudspeaker / Junction boxes. Up to two
dynamic microphones of identical type and characteristics can be connected by
5-pole DIN jacks to the Loudspeaker / Junction Box (refer to Figures 3 - 4 / 3 - 5).
Up to two dynamic microphones for pilot and copilot can be hardwired to the radio.
Even two low impedance (5 Ohm) dynamic microphones may be connected in
parallel as well. However, for microphones with less than 30 Ohms, it may be
necessary to use a suitable microphone transformer due to their low output level.
When hardwiring two microphones they may be connected to two different inputs of
the radio FSG 2T (refer to § 3.5.2.1, Microphone setting). Use single core shielded
wires, connect the conductor of MIC 1 to pin 1, the conductor of MIC 2 to pin 3 and
the shield of both cables to pin 2 (MIC GND) of the radio's receptacle (refer to Figure
3 - 6). The shielding should only be connected to MIC GND at the radio's end and
insulated against aircraft ground at the microphone end. When the microphones
contain PTT keys two additional wires for each PTT key must be connected to pin 7
and pins 11/12 or against aircraft ground.
Never use the MIC GND as ground for PTT key, Intercom, audio or power!