User Manual Part 1

FSG 90F System
3. Installation
November 2000 Page 29
W. Dittel GmbH
3.5.4 Loudspeaker / Headset interconnection
Two separate audio outputs are provided. The speaker output pin 1 can continuously
supply up to two speakers each with 4 Ohms (load > 2 Ohms), while the headphone
audio output pins 2 and 3 can accommodate up to 2 or more headphones each with
some 600 Ohms, or all may be connected also simultaneously.
When no speaker is installed, this Pin 1 may remain not connected, no spare load is
required.
CAUTION!
• The magnet compass will be deflected by the speaker's magnetic
field. Therefore, when using the Walter Dittel compact speaker box
F10061, a minimum distance of 1.3 m/4.3 ft. between compass and
speaker is required.
3.5.5 AF External Operation
The AF external input pin 4 may be connected to any external (selectable) audio output
of any other audio source. 1 Volt rms is necessary to obtain maximum audio volume.
Higher AF input may cause audio distortion. External AF will be audible only in Receive
mode and in Standby mode, and may be heard in both speaker and headphones.
During transmit, the external AF input is disabled.
Continuous interconnection of an external audio source(s) will be suitable especially in
aircraft using just one COM and one NAV. Then the NAV headphone output may be
connected directly to the FSG 90F(X) external AF input.
This allows in addition to the receiving and intercom function also the simultaneous
listening of COM and NAV audio either by headphones or speaker.
Interconnection of more than one external audio source requires additional external
decoupling/isolation resistors (470 Ohms, refer to figure 3-7).
The individual audio volume is set directly at the particular external equipment.
IMPORTANT!
• If external audio sources should be audible via A/C speaker, the external
AF input must be enabled in the SET-UP. The 30 mA current saving in
standby mode is then disabled.
To achieve in External Audio operation the maximum FSG 90F(X) AF output power, a
minimum AF input level of 1 Volt rms is required (approx. 10 kOhm input impedance).
Interconnecting AF wiring must use shielded wires in order to avoid interference from
strong electrical fields. A possible magnetic interference coupling shall be especially
regarded (distance from high current carrying wiring).
3.5.6 Lighting the Frequency Display
IMPORTANT!
• Lighting operates separately and will not be controlled by the radio.
• In order to save current while supplied from battery an external suitable
illumination switch is suggested.
The FSG 90F(X) includes a display which can be back-lit. Pin 23 may be connected
either directly to 14 Volt or to the switched 13.3 Vdc output Pin 24 (perhaps via a
suitable dimmer). For dimmer operation from 28 Vdc supply, insert a 680 Ohm resistor /
0.5 W, connected in series.
CAUTION!
• This way of matching to 28 Volt is only suitable for the lighting!
• The FSG 90F(X) always requires a 12 to 14 Volts DC supply.