VHF Not transmitting?

Ruffles

Ruffles

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26 Feb 2004
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Boat: Portsmouth, Us: Stewkley
www.soulbury.demon.co.uk
Tried calling up a marina on the VHF last week and was ignored. Thought it might be the quality of my conversation. So tried the dreaded 'radio check' on channel 16 with Solent coastguard the next day. Again no reply.

But the radio, an old SWIFTECH M-168, is receiving fine. Now I've been a bit worried about the antenna (Vtronix Hawk Whip antenna) for a while since it is showing some corrosion. So I tried the emergency arial but again no reply.

Is this definitely the radio rather than the antenna? Is it worth getting fixed bearing in mind that a new DSC unit is 150 squid???

Rob.
 
If you do a search of these forums for "SWR meter" you will find lots of discussions on similar issues - it will give you an accurate indication of whether the problem is the transmitter or the antenna.

If it is the transmitter then IMHO it is not worth try to fix.
 
I had this problem regularly on previous boats and it was traced to moisture getting into the outer braid of the antenna feed coax. Only a replacement cable did any good. There are of course other possibilities but I'd investigate that first.

My handheld continues to receive but won't transmit if the batteries are low.
 
Solent Coastguard either ignore requests for radio checks on channel 16 or respond with a request to use channel 67 for this purpose as they have issued frequent requests for sailors to use channel 67 for radio checks
 
Sounds like I need to check it myself using another radio. I brought the unit home with the emerg. aerial for that purpose. I think I have an old handheld one in the garage...

I very rarely use VHF. Ch 80 on a bank holiday w/e is virtually useless to book berths - why do all marinas use the same freq.? Easier to use the 'phone IMO.

The only time I have used Solent CG before for a radio check was after rewiring some years ago. And then only at a quiet time of day.

Rob.
 
It would be worth checking the mike - as the transmit button is on there - make sure it is working correctly ... I currently have a working one in the back of the car and can do some basic MM tests if you want to compare ....
 
if you can reach the antenna, attaching a 12v flourescent to the antenna with tape, key mike and light should light up if transmitting.
 
The mike button is causing the TX button to come on and muting the receiver. Doesn't mean that the mike is sending audio to the unit though. I'll check.

Come to think of it since we now have a 20 month boy who has discovered all these buttons at the navigators seat it is quite likely to be a damaged mike!

Rob.
 
Had a very similar problem to you on 2 occasions. The first was down to the Co-ax plug pulling out of the aerial (from the outside it looked fine, also a Hawk), on the second it was down to a low voltage on the battery. The aerial is easily sorted and just requires the knurled nut undoing, the connector pushing fully home and the nut doing up again. Hope that helps.

Yoda
 
If an antenna (and co-axial cable) is not working 100%, it is very common to be able to receive but not transmit. The only certain way of testing is with a SWR meter, but a simple test which should give a reasonable indication is with a DC ohmmeter. Disconnect the antenna connector from the radio and check the resistance between the inner and outer. It should be very low ( 1 - 2 ohms) because there is effectively a short circuit to DC at the antenna. If the resistance is higher than this, suspect poor connections which will allow reception but not transmission. The short circuit at DC, by the way, becomes an open circuit at VHF frequencies.
 
I had exactly the same problem on the same model of radio three seasons ago. One weekend it was working fine, the next weekend I couldn't raise the marina I was going into, although it received fine. I reverted to using my handhelf VHF and tested the main set against the handheld - it was failing to transmit. I knew it wasn't the aerial or cable as both had been renewed the previous winter when the mast was down and had been working fine. I took the radio out, took it into Greenham Regis at Shamrock Quay - they tested it and diagnosed a duff main circuit board which they replaced. They returned it fully working with a 3 month guarantee and it's been fine ever since. The cost of the repair was £66.

I reckon it may well be worth repairing bearing in mind that any replacement radio will inundate you with DSC alerts. It can't be long before there's a market in second hand non DSC radios.

Good luck,

Ed
 
<<£66 is an amazing price for an hours labour + parts>>

Do you ever take your car to a Main Dealer for servicing?

Don't worry about the DSC alert thing. There is an element on the Fora that massively overstate the Alert thing. If you sail within the Solent the chances are that you'll never hear one.

I've been wondering if the DSC on my set is functioning properly cos all that I hear are massive numbers of idiots asking for Radio Checks on 16.

Martin
 
I also had this problem last year.
As far as I could determine there appeared to be some corrosion at the in line fuse terminals - I think probably enough power got through for receiver but not for transmitter.
Works after cleaning but still not great - I look forward to reading other replies.
Alan
 
I had a problem last season with a radio that functioned well for many (3) years mounted on the ceiling of my pilothouse. Along with that problem, the keypad locked-up. It appeared to be getting over-heated due to poor air circulation because of it's overhead mounting added to the sun's heat transferring through the roof of the pilothouse.

The problem wasn't noticed untill we were trying to hail the harbour we were entering. Quickly rigged up 20+year old back up radio only to find it would recieve ONLY! Entered the harbour and spoke to master of com problems so as not to ruffle feathers.

Pitched both radios and bought NEW (instead of NEW TO ME) Standard Horizon VHF and couldn't be happier.
 
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