VHF Radio not transmitting.

[iain3915]

I have an Entel HT640 handheld VHF radio that will receive but not transmit. It is not on vox so I don't understand why it will not transmit.

Any ideas?

[Steve_B]

Check the antenna. I have had simular probs and this was found to be the fault.

If you can remove antenna and ensure all contacts are clean and fault free

[m chappelow]

DONTpress transmit with the antenna removed as you will blow the tx transistor ,

[Stoo]

I noticed my Standard Horizon was not transmitting well the other day. It seems to be receiving OK, although there's virtually no traffic on the air these days...

I have a second one hooked up in the house and will wire it up in the boat tomorrow, but I wonder if it might also just be faulty antenna connections. I don't suppose there's really anything that can actually "break" in a fibreglass antenna is there?

[MikeCC]

Might also be possible that there's some crud/corrosion in the PTT switch? You probably won't want to take it apart to maintain waterproofness though.

[Stoo]

Originally Posted by MikeCC

Might also be possible that there's some crud/corrosion in the PTT switch? You probably won't want to take it apart to maintain waterproofness though.

Interesting thought. The radio has been sitting in storage all winter, so that's a possibility I suppose. As for taking it apart, it ain't working now, so there probably isn't much to loose! Maybe I'll try clicking it a few thousand times first...

[jyasaki]

Originally Posted by MikeCC

Might also be possible that there's some crud/corrosion in the PTT switch? You probably won't want to take it apart to maintain waterproofness though.

You can usually tell if thats the case by lowering squelch until the radio receives white noise. Push the mic switch, and if the hiss stops, it's seeing the mic switch.

jky

[Ocean Rider]

Couple things to check:
1) wires may be corroded, very common reason
2) make sure batteries are fully charged
3) make sure you have a good ground

Transmitting draws alot more power than receiving and any one of these reasons can cause failure to transmit even though you receive fine. Another idea after checking all others is a new VHF, they do fail and if you are having any of the above issues it will take its toll on the actual radio over time. You can get a communications company to come and check the radio's output and receiving power, commercial boats have to do this and receive a certificate every few years so there should be somebody in your area that can do this for you.
Good Luck!

[jyasaki]

Good point.

If you have any hobby radio guys in the area, likely they'll have an SWR meter that will check what's getting to the antenna.

Here's what I would do:

1) Put a meter on the power input to the VHF, and make sure you're not dropping voltage significantly between listening and transmitting.

2) Check the display and see if the Tx marker comes on when mic is keyed, or listen and make sure speaker shuts off when mic is keyed.

3) Check output with SWR meter (if possible)

4) Swap antenna and VHF to isolate the problem to the radio itself or wiring/antenna.

5) If it's the VHF itself, might be worth swapping mic's (if easily removable) to see if it's the microphone in the handset that's bad before tossing the entire unit.

Hope this helps;

jky

[Stoo]

I disconnected and reconnected all of the power and antenna connections with judicious use of a little emery cloth where things looked less than pristine. Without doing anything else, the radio seemed to be working better. I was able to chat easily with someone a couple of miles away, so hopefully that's all it was.

I think I'll keep my extra radio under the seat just to be on the safe side... and I already have a spare antenna there~

Thanks for your assistance all!

[Rigaud]

Originally Posted by Stoo

I disconnected and reconnected all of the power and antenna connections with judicious use of a little emery cloth where things looked less than pristine. Without doing anything else, the radio seemed to be working better. I was able to chat easily with someone a couple of miles away, so hopefully that's all it was.

I think I'll keep my extra radio under the seat just to be on the safe side... and I already have a spare antenna there~

Thanks for your assistance all!

You have the original length of coax from the antenna I hope? A big mistake is when people cut the wire shorter because it's longer then they need. That has a major effect on SWR and even more so on these VHF radios then 10m. But as mention above a SWR meter is a must with any 2-way radio to make certain all is well in tune.

My rib is coming out of storage this week and reading all this has reminded me to verify 100% all electrical.

[Stoo]

Oh ya, still have the original cable length. Nothing has changed since I put it away in the fall, so hopefully it was just a little corrosion...