ryan TCAD 9900 - Checkout

Revision 4 - December 17,1998 Ryan TCAD 9900 Series Page 6-5
6.3 CHECKOUT
Final checkout of the TCAD should be done away from reflective areas. Non-reflective
areas can be found a few hundred feet from aluminum structures such as hangars, or
opposite the corner of the hangar where reflected signals will reflect away from the
aircraft, not toward it.
6.4 INSTALLATION IN A SEVERE EMI ENVIRONMENT
Good grounding of the TCAD Processor and associated interconnections (particularly the
encoder) is essential.
Many precautions have been taken and tests have been conducted to insure trouble-free
operation of the Processor in high EMI environments. Nonetheless, common sense should
be used when deciding on the mounting location of the Receiver/Processor. Clearly,
mounting it close to L-band transmitters like DME or transponders should be avoided. If
the Receiver/Processor must be mounted near an L-band transmitter, make sure the
transmitter antenna cables are well shielded, and the L-band transmitter units are not
emitting high levels of EMI. In addition, shield the TCAD cables per the notes on the
wiring diagrams, Figures 2-14 or 2-15.
6.5 MALFUNCTION INDICATIONS
PROBLEM: TCAD shows 00 (+100 or -100) feet and 0.3inm or less (The TCAD sees
the host transponder):
This should never happen. Occasional own-transponder indications are not acceptable.
Malfunction of the Transponder Coupler circuit is the problem. Check the Coupler
connections and transponder output. The Coupler will not function properly when the
transponder output is less than 50 watts.
PROBLEM: TCAD shows the traffic to be closer than it really is:
This is caused by an installation where the actual loss from the antenna to the TCAD is
much less than 3dB. Insure that nothing else could be causing the problem, and the range
error factor is consistent all around the aircraft, both from ATC indications and visual
estimates. Additional cable may be necessary to bring the antenna line into design
conformity.
PROBLEM: TCAD shows the traffic farther away than it really is:
Check the antenna connections, and Proper cable length. If these check, contact the
factory.
PROBLEM: Erroneous or missing altitude display:
Check the altitude lines for shorted or open connections.
PROBLEM: Whine in the Audio caused by TCAD:
The TCAD audio return line should be connected to the TCAD audio port at the Audio
Panel.
Check the primary source of the audio noise. Reduce the noise from this source as
required. If the problem persists, shield the encoder lines and the audio line. Normally the