VHF / AIS unit receiving but not transmitting VHF calls

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SV Kittiwake

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Our new B&G V50 VHF / AIS Receiver seems to be receiving ok, we hear radio calls and can receive AIS signals from as far away as 15-20Nm.

But the other day we were coming into Carloforte harbour and radioed the marina... No response. Tried a couple more times with no response. Tried on the handheld VHF and they responded straight away. I could hear the handheld on the main radio, and I could hear the marina's response on both the handheld and the B&G. We've also since tried contacting Cagliari coastguard (about 14Nm from our current position) for a radio check and not heard anything back.

I can hear our B&G radio's calls on the handheld VHF. So I think the Mic is working fine.

Given that the AIS is picking up signals from far away, I'm reasonably confident in the aerial... unless it's possible for the aerial to be picking up AIS signals but can't transmit VHF voice calls?

I tested the wiring connection at the radio, and it shows 13.1 volts with no transmission, 12.0 volts when transmitting on high power, and 12.9 volts when transmitting on low power. So I think the power connection is ok.

Has anyone got any other ideas for what to look for? Am I right or wrong to think it's not the aerial?

For info the aerial is a Banten S/S Whip, bought from Force4. Maybe it's just too rubbish to transmit far enough? These are the specs:

S/S VHF Whip with Windex - This combination of stainless steel whip aerial with wind indicator is very popular as it saves space at the top of the mast. This lightweight and high performance 1.05m aerial is designed to give maximum transmitting and reception performance.
• Frequency: 156-163 MHz
• Gain: 0 db
• Impedance: 50 ohm
It comes complete with 18m of RG-58 cable, masthead flat bracket.
 
Can you return to your dealer for it to be sent back and tested? Assuming you have made the plug off correctly and you have a half decent SWR, you've done everything you should technically need to do as a consumer for this to work. Navico are very good on their technical line.
 
Thanks both for your responses.

I've gotten in touch with BandG to see what they say. As I got it online from a UK shop and I'm now in Sardinia, trying to send it back is a last resort really - if there's a quick fix then I'd much rather try that. I'm going to go up the mast and check that it's not the connection at the top.

I measured the Coax cable which came with the aerial and it's only 5mm diameter. There's probably about 12 metres of it - could that be causing a problem? Salty John recommends thicker (7mm I think) coax for runs over 10m. If that's a potential issue then step 2 could be replacing with better / thicker cable. Although this would be a bit of a faff as the current coax runs in a conduit tube on the outside of the mast and only just fit through.

Thanks again.
 
I had exactly the same problem which turned out to be the aerial. It was tested which highlighted the problem. I didn’t even think it could be the aerial as it was only 3yrs old.
 
Thanks Robert, seems strange that the aerial helps to bring in AIS signals though? Or maybe the coax is acting as an aerial which is strong enough for that?
 
SV Kittiwake said:
Thanks Robert, seems strange that the aerial helps to bring in AIS signals though? Or maybe the coax is acting as an aerial which is strong enough for that?
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Signals can be received using the coax alone, transmitting is a different story and i'd suggest you don't try to transmit until you get it sorted. Trying to transmit with a faulty antenna, coax etc can damage the radio.

For the sake of a few quid on Ebay, a used VSWR meter is a good investment.
 
Thanks Paul, it's not so much the buying it which is the problem but receiving it when out in Sardinia, which could take weeks. If I can't get a quick fix sorted then I'll look into buying one as well as any other bits I need.
 
Sounds like the connection between the aerial and the coax, then. Did you have to assemble this when new, or was it already connected? Last aerial I bought, I had to make the connection.
 
Yep, that's what I'm going to investigate first I think. that one was actually already installed but in my investigations I've read that some people have had trouble with that end even though they're thought it'd be 100%. Will be annoying to sort though, either pull the wire out and rethread it or get a butane torch and resolder the connection at the top of the mast...
 
SV Kittiwake said:
Thanks Paul, it's not so much the buying it which is the problem but receiving it when out in Sardinia, which could take weeks. If I can't get a quick fix sorted then I'll look into buying one as well as any other bits I need.
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No probs, had failed to notice where you were located.
 
A emergency VHF aerial is quite handy for not just emergencies, but also troubleshooting these kinds of issues. Just plug it in the back of the radio and see if anyone hears your radio check now. You're welcome to borrow ours for diagnostics, if we ever catch up with you (still in Mallorca, hopefully crossing to Menorca tomorrow).
 
Cheers guys! We found Menorca crazy busy even before July, but Sardinia has been heavenly so far! Will definitely take you up on your offer when you catch us up, thanks.
 
So to finish this thread off... we ordered an SWR meter, and came into a Marina in Cagliari to sort out the issue. Wanted some calm water for going up the mast and access to chandleries for bits and possibly a new antenna. Turns out the problem was with the assembly of the connector going into the Banten antenna.

I guess there's two things to learn - we should have done a radio check when we were in the yard, it was stupid of us not to do it and I'm not sure why we didn't. The second thing is that Banten antennas are not well assembled it seems. The central conducting wire wasn't exposed at all, so no connection was getting through. As it's not a common connector type it was hard to find instructions on how to assemble it online, but I made some assumptions and sorted it. Although Bantens haphazard assembly has cost us a Marina stay and some dead legs dangling up the mast.

SWR meters are great though, and if anyone wants to use ours you're more than welcome to if we're in the same port!
 
SV Kittiwake said:
So to finish this thread off... we ordered an SWR meter, and came into a Marina in Cagliari to sort out the issue. Wanted some calm water for going up the mast and access to chandleries for bits and possibly a new antenna. Turns out the problem was with the assembly of the connector going into the Banten antenna.

I guess there's two things to learn - we should have done a radio check when we were in the yard, it was stupid of us not to do it and I'm not sure why we didn't. The second thing is that Banten antennas are not well assembled it seems. The central conducting wire wasn't exposed at all, so no connection was getting through. As it's not a common connector type it was hard to find instructions on how to assemble it online, but I made some assumptions and sorted it. Although Bantens haphazard assembly has cost us a Marina stay and some dead legs dangling up the mast.

SWR meters are great though, and if anyone wants to use ours you're more than welcome to if we're in the same port!
Click to expand...

Glad to hear you got it sorted and glad you found the SWR meter useful :encouragement:
 
I had a similar problem when trying to call Gouvia Marina this summer. Several calls without any response until I switched on the 25W transmission . A short blast on this brought a very prompt response from the Marina. My question is, whether you were transmitting at low or high power.
 
Hi Leonidas,

When we were calling the Marina we were calling (and not getting through) on low power. When we were trying to do the radio check with Cagliari coast guard, we were around 10 miles away from them and calling on high power.

Once we bought it, the SWR meter showed poor readings (2-3) for both low and high power. I think our handheld was picking up the call by virtue of it being so close to the boat's vhf. After I made the antenna connection better, these both dropped to less than 1.2.

Have you tried a radio check with the local coastguard? It's hard to tell 100% with the Marina call situation, whether the guy just wasn't able to respond to the first call.
 
I would add my view on the radio but I think you have it sussed. However, if you have a handheld and can transmit to it quite clearly then it is reasonable to assume the aerial is working correctly.


Sardinia on the other hand is one of my favourite places to sail. Check out the south side of the straights and be sure to stop off at Portisco and Porto Rotundo, just south of Porto Cervo. Littered with super yachts for very good reason, it's beautiful.
 
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