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1. 10:38 AM - Re: King KX155 weak VOR reception (D L Josephson)
2. 02:41 PM - Re: King KX155 weak VOR reception (Jimmyb)
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| Subject: | Re: King KX155 weak VOR reception |
On 7/13/14 11:58 PM, Avionics-List Digest Server wrote:
> *
>
>
> 1. Do you think it's likely that the open multiplexer port could be causing my
> issues?
It's possible, but not too likely to cause the severity of symptoms you
describe. You could eliminate the nav splitter by taking it out of the
circuit, connecting the antenna lead to one VOR or the GS only, and
seeing if the problem remains.
>
> 2. How likely is it that the old RG58 cable could be causing my issues?
Not likely, unless it has gotten mashed somewhere. More likely that a
connector or the termination between the antenna and the cable has
failed. I have 50 year old RG-58 that's still fine. There's no practical
difference between old RG-58 and LMR400 in your application -- there
will be more loss in the additional coax connectors than there is
difference in attenuation.
You could try an old vee dipole bolted on to the underside of the tail
as a test.
>
> 3. Should I bite the bullet and buy an antenna analyzer such as the rigexpert
AA
> 600?
Since you can't get to the antenna, no. An "antenna analyzer" will not
tell you whether you have an effective antenna, which may be very
different from 50 ohms but still work fine, or an open at the end of the
cable. A 50 ohm resistor at the end of tiny coax will look great but
won't be a very good antenna. The best comparative test will be with a
low power VOR/GS ramp tester.
Message 2
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| Subject: | Re: King KX155 weak VOR reception |
Re my interest in an antenna analyzer: I've been looking at some of the newer
units online (such as the Rigexpert AA-600) and it appears they have the capability
of testing the coax for faults (distance to fault) while connected to the
antenna. I wasn't thinking of replacing the RG58 with RG400 simply because
of the RG400 is a lower loss cable, rather I wanted to use the analyzer to check
the RG58 for faults. I would replace the RG58 with RG400 ONLY IF the RG58
is questionable (open, shorted, etc). This BTW may be a real possibility because
the existing cable makes some pretty tight bends under the panel. Also
using a tester such as the AA-600 would allow me to check the SWR of the antenna.
Thoughts?
--------
Jim
Phoenix, AZ
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http://forums.matronics.com/viewtopic.php?p=426666#426666
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