VHF Radio intermittent

[Halo]

My VHF was "weak unreadable" this morning. By this afternoon it was "weak readable" in a less favourable spot but the weather had dried up . I have noticed for a while an apparent effect that the radio works ok when it is dry but not when it is wet - is there a scientific reason why an aerial can work in the dry but not when wet ?
I am trying to avoid going up the mast and changing the aerial unless it is strictly necessary
Many thanks for any insights
Martin

 

[Spyro]

Possibly a short between the outer screen and the core caused by dampness. Unusual for it to dry out if it's actually in the cable. Maybe wet in the connector area. If it's definitely only troublesome in the rain a trip up the mast may be required.

 

[Daverw]

Some nds like water in the antenna mounting and getting into coax. I would change it before it fails completely unless you don’t consider your VHF that important

 

[VicS]

I take it there's no deck connector involved.

If there is that would be the first thing to look at

 

[jiris]

You are almost certainly getting water in the coax. The problem is more than losing communication. Poor antenna can cause reflecting radio signal back in the radio, where it converts to heat. Especially while transmitting on high power for a prolonged period of time it can cook the final stage and render the radio beyond economical repair.

 

[MM5AHO]

Most modern transmitters throttle back the output power when a high SWR is detected. The days of burning out the final stages are pretty much gone.

 

[William_H]

I think OP needs to be sure of his results first. Radio propagation can be a bit variable at extreme range and a bad readable signal report might result from proximity of your mouth to microphone or conditions at the receive end. If you are really sure it is bad in wet weather then yes antenna and cable might be suspect. Perhaps easiest solution is to fit a standby antenna on the push pit and compare results. If that seems to work better than the mast top one then yes you have a problem. olewill

 

[Halo]

Just to close the loop on this one.
I confirmed the radio worked better in dry weather, bought a new aerial and fitted it. The old wire had chafed at the inside top of the mast and worn through to the core which was exposed. New aerial works great and CG can pick me up on 1w !
Martin