Kingsley Pvt Mail wrote:
>
> Tony,
>
> If the elevator push rod/tube down the centre of the fuse is a potential
> problem, would the rudder cables also be likewise?
>
> I have just revealed to the world my sum total knowledge of radios etc.
>
> Regards
> Kingsley
I know an antenna engineer (aviation mfr no less), but he can't
predict the exact effect of such things. He can explain why xponder
mfr's universally say on the bottom of the A/C, 6" radius ground
plane, 9 feet or less of coax in lieu of their low-loss ($$) kit,
several feet from conductive elements in the radiating pattern
(horizontal, peak at 30-deg down from horizontal). Too far aft in the
fuselage is going to violate a rule or two, and too far above the
floor if internal will require reception/transmission thru people who
absorb RF, an engine which either blocks or causes multipath problems,
and a carbon fiber prop to add modulation to signal and send garbage
to ATC. The thing about xponders is neither they nor ATC can tolerate
poor signal, whereas a comm can be read if distorted or scratchy. A
VOR needle may just wiggle now and then.
If problems arise, an avionics shop cannot test the antenna except for
gross failure. Consider FAA's statistical study of small-plane
xponder installations in the field, and they found that these boxes
over half the time are out of tolerance, but generally close enough so
that ATC can deal with the error. Meaning to me that a compromised
antenna setup can cause wasted money to a shop for bench-tweaking a
"problem" that a good antenna would have masked. They also found a
significant percentage of times where the box would not accurately or
at all responded to TCAS interrogations. Since we can't afford TCAS,
I think it would nice if high-speed, by definition, aircraft on a
collision course can pick you up.
Regards,
Fred F.
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