VHF stops receiving after about a minute

[Wainui]

I turn on my VHF and it works fine for about a minute then fades out and will not transmit or receive. Older antenna up the mast. Does this sound like an antenna problem?
Thanks

[Wotname]

A bit more information would be helpful, like:
What model
Does the display fade as well
Do you still hear receiver noise when you open the squelch and does this respond to the volume control

However from the infromation as posted, it sounds to me like a faulty radio or perhaps bad power wiring to the radio (corrosion in connectors or terminals).

[Celestialsailor]

I'd say it's broken...buy a new one.

[skipmac]

Originally Posted by Celestialsailor

I'd say it's broken...buy a new one.

Based on the limited information this is the most likely answer. An electrical component like an IC, transistor, etc losing function as it warms up is a common failure mode.

Generally a bad power connection isn't that temperature dependent. Won't hurt to check the power to the unit but may be new radio time.

[hamburking]

I agree with the comments above.

If its a basic unit, cheap enough to replace.

However, if you want to try to save it, why not open up the case, attach power, and see whats going on inside. Often it can be an obviously loose connection or component, or a part that is clearly overheating. If its broken anyway, wouldn't hurt to look.

Also, you might want to test the power wires to the radio...it would be a shame to toss a working radio because of a wiring problem on the boat side of things. Simply attach the radio to a different power supply and see if you get the same results...or start by putting a voltmeter on the power cables to the radio and see whats what.

Also, remember to save the wiring harness, connectors, and even the mic (if it unplugs) in your spare parts...you never know when they might come in handy.

Good luck.

[phaon]

A bad capacitor can cause that kind of issue. Charges for a minute then can't hold it's charge and fades out. If you open it up look for the components that look like small beer cans, often with a crease across the top. You might have a couple of larger caps and a bunch of smaller ones. Look to see if you can find one that is swollen, puffed out. YOu can replace them cheap if you can solder. Remember, most have polarity, plus & minus, they'll be marked.

[hellosailor]

Definitely a simple cheap component overheating and not an antenna problem. Should be a simple fix but if you don't know electronics and soldering, the minimum charge in a shop will often be as much as the cost of a new radio. If you can find a ham or other hobbyist to take a look at it, try that. Otherwise...cheaper to replace, sad to say.

[MarkSF]

I foresee a new radio in your future.....

[Celestialsailor]

Cripes! We're talking $89 for a new one.

[Wainui]

Thanks for the replies.
It is a West Marine VHF480 Fixed VHF Radio $120.
Display works fine. I unplugged the antenna and ran the radio for a few minutes then plugged it back but no go.
At least its not the antenna or cable.
I will take it apart to see if its obvious what the problem is or just by a new one, but definitely not a West Marine unit.
Regards
M

[Don C L]

Upgrade to one with GPS and perhaps AIS receiver, you'll love it!

[Wainui]

Power Transistor is the problem. Replacement aprox $50. Worst Marine just refer you to Uniden who charge a flat rate of $45 plus shipping.
A new unit, Standard Horizon GX 2200 with AIS is in my future.
Thanks

[hellosailor]

That may be garbled. A $50 power transistor would either be a very powerful one, or one marked up several times to "retail plus". On the top of the power transistor will be an identification code, I'd suggest checking with DigiKey, Mouser, or Newark Electronics and I'd expect they can sell you a new one for $10. Assuming that really is the problem.
Because those transistors normally control the transmission power, and when they are blown the receiver usually still works perfectly--you just can't transmit.
A $45 flat repair is not unreasonable, even if you just send it out to keep as a spare afterwards. You might also ask Uniden if they would consider taking the radio as a trade-in towards a new unit, instead of repairing it. Some companies are glad to do that.