Antenna Problem

[jdifabio]

Just moved external antenna today for Kenwood. It is the same antenna, moved about 20 feet onto new pole. Worked fine before the move. When I go to attach antenna to back of radio, when center of coax connector is inserted into radio antenna connector, reception is 100% (listen to weather frequency), when I screw the outside of the coax connector onto the radio antenna connector, I loose reception. Are these symptoms of a particular problem. !! Thanks in advance. Joe

 

[Golay]

Same coax?

Are you using the same feedline?
Just a guess that you have the shield and center conductor shorted in the coax,

 

[zz0468]

Are these symptoms of a particular problem.

Yep.

Thanks in advance. Joe

You're welcome, Joe !! =)




Seriously... (?)

I would suspect a problem with the coax. You say it's the same antenna. But is it the same coax? Is it the same connectors? What exactly has changed? Look there.

 

[jdifabio]

Thanks for reply, yes same feed line, same everything. Very puzzling

 

[jdifabio]

will trouble shoot coax, thanks

 

[zz0468]

Thanks for reply, yes same feed line, same everything. Very puzzling

Got a VOM? "ohm" it out. Check for a short between the center conductor of the coax and it's shield. Check for the same on the antenna. Got a short on the antenna? Then better check to see if it's supposed to be there.

That's about all I've got. You didn't give us much to work with.

 

[jdifabio]

appreciate all the input, will check for a short tomorrow, thanks again for the responses.Joe

 

[majoco]

What sort of antenna? If you have something where the whole antenna is isolated from the structure, a proper J-pole for example, then disconnecting the outer of the coax makes the whole lot joined to the inner and you may get a good signal at some random frequency - as soon as you connect the outer the signal may drop but over it's bandwidth should be more balanced reception. Happens on HF too if you have a balun up at the top.

 

[n5ims]

I would suspect the coax and/or connectors. It could be something as simple as the center connector has broken somewhere in the coax during the relocation and with the very strong signal from the NOAA Weather Alert transmitter you can hear the signal from just the part of the center connection from your connector and once you put the shield in place (by screwing the outside of the connector down) you no longer can receive the signal. It's also possible that simply by moving the coax you caused some of the shield to short against the center connector, which would also cause what you describe (basically you were lucky that it wasn't shorted previously but after the move you weren't quite so lucky).

If you made changes (new coax, a jumper of come kind, moved the antenna from a PVC mast to a metal mast, etc.) you'll need to investigate further to see if any of those changes may have caused issues.

 

[spongella]

Also check the antenna to make sure there are no shorts or mechanical problems.

 

[jdifabio]

Thanks to all, loose antenna mast seemed to be the culprit. Thanks for the VOM suggestion, that got me thinking plus a good nights sleep and daylight I had issue resolved within and hour. Joe