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posted to rec.boats.cruising,rec.boats.building
derbyrm
 
Posts: n/a
Default Measure VHF Antenna (Cable) ?

Interesting. The aircraft whips seem to get by without a loading coil at
the antenna. Anyway, all that means is that you disconnect both ends of the
cable before checking.

Roger

http://home.insightbb.com/~derbyrm

"Bruce in Alaska" wrote in message
...
In article i35Rf.817913$x96.597697@attbi_s72,
"derbyrm" wrote:

I'd certainly check to see if the center conductor is shorted to the
shield.
(Near zero ohms with the cable disconnected from the transceiver.) That
was
a common failure mode on the old Nike missile system. Where the cable
makes
a sharp turn the center conductor would push thru (slowly) the
insulation.
Wiggling the cable to detect an intermittent short is also something I
would
try.

Of course, if it is shorted and you tried to transmit, you may have fried
the transmitter.

Roger

http://home.insightbb.com/~derbyrm

"Chris" wrote in message
ups.com...

Anything I can do with the multimeter I have here?




This would NOT nessesarily prove anything, one way or the other.
Many VHF antennas are designed to have a DC Ground on the Center
Conductor of the coax connection. Also 99% of the VHF Marine
Radios on the market for the last decade or so, have Power Foldback
Circuits that detect High SWR on the Feedline and reduce the Power
Output so as to not over dissapate the RF Final Amplifier.

Bruce in alaska
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