FSG 70/FSG 71M
O
PERATION
M
ANUAL
Page
3 - 2
Reprint July 1998
W. Dittel GmbH
3.2.1
Matching the Microphones
The output voltages of dynamic microphones are differing reasonably depending on
type, number of parallel connected microphones, and speech volume.
To utilize the high quality of our transceivers, we recommend matching of the
microphone-set in use to the microphone input of the transceiver as follows:
a) Connect the microphone-set (max. 2 microphones of the same type) via test cable
or on-board wiring to the transceiver.
b) Turn microphone gain potentiometer (see Fig. 3-1) fully ccw. Set sidetone level
control to any position (except the full ccw position) and check the headphone
output level.
c) Switch ON Intercom. Talk into one of the microphones with typical loudness and
distance. Adjust microphone gain potentiometer cw, until no more increase of the
amplitude on the CRT is visible (control threshold). Check both microphones, they
should have the same adjustment.
d) Secure microphone gain potentiometer by any staking lacquer.
IMPORTANT!
a) The speech volume of course is higher in a noisy powered glider or in
an Ultralight than in a silent fiberglass glider.
b) For standard carbon microphones no matching is required, but they
should be checked in the way mentioned.
3.2.2
Audio Sidetone
With the
FSG 70/FSG 71M
transceiver, a part of the modulation signal is fed to the
headphone output as long as the transmitter is operated. The sidetone control (see
Fig. 3-1) should be set so that the tone is audible, but not too loud. Please consider the
ambient noise in the aircraft when adjusting.
The volume in Intercom mode is about the volume of the audio sidetone and can not
be adjusted separately.
AUDIO SIDETONE CONTROL
Identification Label
MICROPHONE GAIN CONTROL
FSG 71M
only
Battery label
Fig. 3-1 Location of Audio Sidetone Control and Microphone Gain Control
