I have a VHF radio connected to an antenna on the mast,
which does not make a sound. It has power, the lights on
it come on, but not a sound on any channel.

I suspect that the cable leading to the antenna is bad,
disconnected, or whatever. (Does this sound like the likely
cause?)

To check this, what do I have to measure in antenna/cable:
Impedance? What does an ok antenna cable show?

Thanks!

"Chris" wrote in message
oups.com...
I have a VHF radio connected to an antenna on the mast,
which does not make a sound. It has power, the lights on
it come on, but not a sound on any channel.

I suspect that the cable leading to the antenna is bad,
disconnected, or whatever. (Does this sound like the likely
cause?)

To check this, what do I have to measure in antenna/cable:
Impedance? What does an ok antenna cable show?

Or you can borrow a friends (known good) spare antenna and plug it in for a
quick test.

Chris wrote:
I have a VHF radio connected to an antenna on the mast,
which does not make a sound. It has power, the lights on
it come on, but not a sound on any channel.

I suspect that the cable leading to the antenna is bad,
disconnected, or whatever. (Does this sound like the likely
cause?)

To check this, what do I have to measure in antenna/cable:
Impedance? What does an ok antenna cable show?

Thanks!

A spare, portable antennae is quite common since the masthead antennae
is vulnerable to a number of mishaps; I carry a suction cup version.
This could be a good time to invest, or you should be able to find
someone that has one. Another possibility is a signal strength meter.

Anything I can do with the multimeter I have here?

Chris,
In a Word - NO
The antenna on the mast may well exhibit a very low DC resistance.
The spare antenna suggestion was the best. If you do not have one.
plug any piece of wire into the center of the antenna connection and set
up to the local weather tx.

If you get something, you have an antenna problem. Most of the time,
this is cable damage (like getting the coax under the mast when it was
stepped).

If you still can not get any weather channel, undo the screws on the
bracket (save them) and frizby the whole thing (repair is seldom
ecomomicly viable).

At the price of a bench hour, it is seldom that a tech can complete a
diagnosis for less that half the cost of replacement.

Matt Colie

Chris wrote:
Anything I can do with the multimeter I have here?

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?

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
--
add a 2 before @

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
--
add a 2 before @

Some antennas have a loading coil at their base. This coil is across
the center cable conductor and the shield, so if you use an ohmeter to
measure the resistance of the center conductor to the shield, you will
get a "shorted" indication.
A better check is to find a ham in the area, and see if he has an
'antenna tester'. This will operate the antenna at the intended freq.,
and show if there is a problem with the cable or antenna.
But first, make sure your VHF radio is not at fault, by checking the
squealch setting, and volume control as others have mentioned. You
should hear something from the VHF, even without the antenna
attached...BUT DO NOT TRANSMIT -as that would cause problems with the
radio possibly.

Larry DeMers
s/v DeLaMer
Lake Superior

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?