User Manual Part 1

FSG 90F System
2. General Description
November 2000 Page 15
W. Dittel GmbH
2.9 Accessories required, but not supplied
a) VHF aircraft antenna with coax cable RG-58C/U and BNC connector (Male)
b) Headphone (8 ... 600 Ohms, typical) and/or loudspeaker (2 ... 16 Ohms)
c) Non-amplified dynamic microphone, (4 ... 600 Ohm), or amplified/carbon microphone
(amplified dynamic or Electret mike,), with or without PTT key (separate mike inputs
amplified/non-amplified)
d) Alternatively to b) and c) headsets with similar specifications
e) Battery power supply unit 12 Vdc, minimum 6 Ah, for aircraft without electrical system
f) Push-to-talk key permanently installed on yoke (if a microphone w/out PTT key is
used)
g) 25 pole SUB-D connector type DA-25 S and cover, if no pre-manufactured wiring
harness exists.
2.10 Microphone hints
IMPORTANT
a) Radio system reliability and performance significantly depends on quality
acoustic accessories.
b) Extremely high performance requirements - especially for 8.33 kHz
Technology - demand after installation completion proper acoustics
leveling through SET-UP in order to maintain best radio capability.
Therefore, please do not use low performance acoustics accessories.
c) Dynamic microphone requires shielded wiring. Essential requirement is
consequent separation of microphone ground / shield from any other
ground. This means, dynamic mike ground / shield must be separated
from any other grounds for DC input and DC output, AF input and AF
output like speaker, phone, PTT and external AF input. Other grounds for
DC input and output, speaker, phone, PTT and external AF may be
connected together with the amplified mike ground.
d) Amplified microphones may contain dynamic or Electret acoustics
transducers.
e) Always ensure IDENTICAL microphones are used for parallel operation.
Similar requirements are applicable for headphone characteristics.
f) Always ensure that during SET-UP all of the many FSG 90F(X) functions
are adjusted to achieve optimized radio system performance.
g) Operation of amplified microphone systems close to the radiating
antenna (portable case or located right behind of the cockpit) may be
influenced from strong antenna RF field strength and become unstable,
oscillates or causes modulation distortion. Verify this effects -possible
caused by- by RF replacing the radiating antenna against artificial
antenna / RF dummy load temporarily