Revision 4 - December 17,1998 Ryan TCAD 9900 Series Page 6-2
The bearing antennas follow the same general guidelines.
Structural substantiation of the antenna locations is important and the responsibility of the
installing agency, of course. If a structural DER is necessary, the Aircraft Electronics
Association has resources you can contact. Their number is (816) 373-6565. Willis and
Kaplan in Buffalo Grove, IL has been very helpful and responsive, phone 847-215-7757.
6.2.2 POWER INPUT LINE AND GROUND RETURN
Do not start the engines with the TCAD operating. The drop and surge of the voltage
can, in extreme cases, cause TCAD to lose user defined settings.
Insure that the TCAD is well grounded to an effective airframe ground. Poor grounds or
ground loops can cause intermittent operation or alternator noise in the headphones.
6.2.3 ANNUNCIATOR LIGHT AND REMOTE MUTE
The annunciator light uses a switched ground. Installation of an annunciator light is
optional, but is strongly recommended for best operation. The light should be white, and
identified as “TRAFFIC”.
The remote mute can be engaged or disengaged via a grounded switch.
6.2.4 AUDIO
TCAD audio is designed to operate into a 600-ohm load. If an audio port must be shared
with another audio input, series resistors must be used in both lines to allow sufficiently
high audio for both audio inputs. Usually 470-ohm resistors are satisfactory.
Connection to an audio panel without internal amplification normally requires a
supplemental amplifier.
There is a potentiometer in the TCAD that allows for greater audio output. Contact the
factory for instructions to increase the audio output.
Low audio is usually caused by a greater than normal load on the line due to multiple
inputs to one audio port.
A dedicated audio ground return line is provided to eliminate possible audio whine.
Connect the return to the ground for the audio port TCAD is connected to. If no return
ground is provided, ground to the case of the audio panel.
The audio line from the TCAD to the audio panel should be shielded, with the shield
grounded at one end.
6.2.5 ENCODER LINES
The encoder lines are diode isolated inside the TCAD. A diagram of this portion of the
circuitry is in Section I of the Installation Manual. The common line should not be diode
isolated, and should be the same potential as the encoder.
D1 and D2 are not altitude lines, and should not be connected.
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