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VHF antenna issues?

8K views 47 replies 20 participants last post by  El Rubio 
#1 ·
So, I had a new mast-top antenna installed a few months ago during a re-rig. Had the cable ran (run?) to the base of mast. Installed coax from mast base to the VHF. Then hooked to a "new" Standard Horizon radio.

I can receive from STRONG signals (CG comes in fine, a handheld close by too) Signals from vessels using (I'm guessing) fixed mount radios are not received although they come in fine on the handheld.

SO, the question, WTF is wrong? I'm thinking (OK... hoping) the antenna is fine, the cable from the ant to the radio should be fine ( I did bypass that coax and connected straight to the coax from the mast base, same result)

Could it just be the radio? It was given to me "new" in its box but is several years old. Don't know its origins.

She is about 6 hours away, so not easy for me to diagnose. I, stupidly, didn't try to transmit a radio check to see if it TX's fine.

I guess my first thought is to install a new radio (SH GX1700 looks good) although I really don't want to buy a new $200 radio if it's the antenna that I need.

Thoughts? :confused::confused::confused:
 
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#4 ·
I had the same issue on my setup. It turned out to be an issue with the length of cable between radio and mast base. In the end I replaced it with new cable, and new soldered gold-plated plugs. That did the trick.

In my case I believe the issue was age-deteriorated cable and connectors. In your case it is all new, but termination is still a process that is susceptible to human error.

I think I would proceed by measuring the SWR of the antenna and cabling. If your radio is old and you don't mind getting a new one, I would try that. Thirdly, in my case, I found it helpful to buy and try one of those Shakespeare emergency antennas (which told me that the radio was fine). I kept it as a spare just in case.
 
#5 ·
It's a long shot, and depends on which channels you used to compare with the handheld, but if that "new" radio is just new to you, check that the U/I/C (US/International/Canada) setting is correct. There are some channels which are used as duplex pairs in some locales, and simplex in others. US/Can differ in some, and US/Int'l in more.
 
#6 ·
That sounds like my boat. When I bought it the old radio didn't work. I bought a new radio and pronounced it as functioning when it could pick up my handheld from within the boat. However the next time I sailed away I quickly lost all nearby signals. Turned out my coax was totally busted at the deck connector. If I were smarter I would have checked that before buying the new radio.

So it's possible you have a bad connection to the mast antenna and are just picking up signals through the coax.

I'll cross my fingers that this season, after running all new wires like you, mine actually works.

As another note, check out the Shakespeare solder-less connectors. They were really easy to install.
Shakespeare Centerpin® Gold-Plated PL-259 Connector
 
#9 ·
You've lost me. What ground wire? VHFs are normally connected thus : + and - to the power supply. The VHF antenna cable goes to the antenna. The only requirement for the antenna cable is that the inner core, and the shield, are unbroken, all the way to the antenna. Normally the antenna is isolated from it's mounting bracket. So where does a "ground wire" fit in?
 
#8 ·
gm-
One of those "emergency" antennas does make for a real quick and simple way to find out if the problem is in your radio, or your cable and antenna. Worth stowing away because masthead antennas eventually DO fail and then the spare is priceless.
If the problem is with the radio, call Standard Horizon. They're on the very short list of companies that go the extra mile, every time, for every customer. If they can't find some setting to change, they'll ask you to send it in, and the odds are it is worth repairing.
If the problem IS in the antenna or cabling, then an SWR meter and a multimeter will be needed to do some testing and figure out what's wrong. Sometimes even new equipment is DOA. Sometimes even the solderless patent coax fittings simply don't install properly.
Easiest to use the "emergency" antenna first, and make sure the radio isn't the problem. And of course, you can keep using that while you troubleshoot the rest of it.
 
#10 ·
I think he meant "ground" as in "battery negative". He raises a good point in that voltage drops in the positive supply are easy to find, but when "ground" isn't really "ground", weird things happen. Not only should there be 12V (more like 12.5 to 13.6) at the radio, but the "negative" supply lead should be very close to the same voltage as the "negative" battery terminal - especially during transmit, when the radio is drawing (or supposed to be) several amps.

If there is a problem with the official netgative/ground wire, it's possible that the radio is getting its ground instead via the coaxial cable shield, via the antenna, via the mast, via other grounding or even the nav light wiring - very roundabout, and not a good ground.

Make sure the radio still operates (at least in receive) with the antenna disconnected (i.e. when it is *not* grounded via its antenna cable). Testing with an (ungrounded) emergency antenna as suggested earlier would also show this.

...and check the U/I/C setting.
 
#12 ·
Thanks for all the great replies, sorry it took me a while to respond back.

I think there are several suggestions that bear (bare?) following up on. The emergency antenna is a great one, good to have as a back up. I actually have a SWR meter for a CB and did a quick search to see if I can use it for the VHF and apparently I can although its not totally accurate but can give me an idea of what is going on. Also checking the negative side is a good idea, I did the wiring but the boat is over 40 so another look at the wiring couldn't hurt.

I can actually receive the weather stations as long as I tune the squelch all the way down but it is very faint and, of course, full of static so I might be just receiving through the coax. The signal from the CG comes in crystal clear although I'm sure they're transmitting at some heavy wattage.

My only other thought, other than the radio being bad is the antenna was never attached to the coax cable. I looked up there with the bino's and it appears it is, but I may have to take a trip up.

Looks like I'm going to go ahead and start with the emergency ant. and go from there.

Thanks again for the replies.
Gerry
 
#21 · (Edited)
I can actually receive the weather stations as long as I tune the squelch all the way down but it is very faint and, of course, full of static so I might be just receiving through the coax. The signal from the CG comes in crystal clear although I'm sure they're transmitting at some heavy wattage.
Gerry
Yep..sounds like a connection problem..check your solder joints on those PL 259's..especially the braided portion..

http://www.hcarc.us/articles/soldering PL-259 connectors.htm
 
#13 ·
Gerry-
The CB SWR meter is designed to work at ~27MHz while marine VHF is ~165MHz, so the radio energy from your marine VHF may be "invisible" to a CB SWR meter. The only way to know if it can give you any information, is to try it on a different boat where you KNOW the radio is working well. See if it indicates a reasonable SWR, and then see if it indicates anything similar on your boat. (And even that is a real q&d kludge.)
A real VHF SWR meter isn't expensive and is useful to monitor your radio in the future, if you look for "2 meter ham radio" SWR meters, those are close enough (144MHz) that they always work well with marine VHF.
 
#14 ·
Thanks HS, I found this and thought I'd try it since I have the CB SWR meter:

No VHF SWR Meter? No Problem. -

Not sure how it will work, but will also try the emergency antenna to have as a back up. I've looked around and the emergency ant. and the VHF SWR meters are about the same price and I think both would answer my issue. However, I figure a backup antenna would be a nice addition to the boat...

Thanks Again.
 
#19 ·
I did.

I ended up going with the emergency antenna from Shakespeare. When connected to the radio I can receive as good as the handheld when down below ( and better when placed on the boom). I'm thinking my issue is that the boat yard didn't attach the coax to the antenna when they installed it.

SO, that's my next step, to go up the mast. Unfortunately I live in Southern Ca and the boat is in San Fran. It'll have to be next month as I've just been bombarded with work... Can't wait to sail her down so I can do this sort of stuff "on the fly". Maybe (hopefully) in Sept???? :)
 
#20 ·
Check also the connectors and connections at the radio, and where the ship-side cable connects to the mast-side coax. Every connector is an opportunity for an open, or a short. On a friend's CS with a keel-stepped mast, the radio-to-mast cable had collected enough moisture down in the locker/bilge next to the mast entry that when I tried to strip it back and re-terminate the PL259, all I could get was black powder where the copper shield used to be. After cutting back a few inches, 6 inches, a foot, another foot... he decided to run a new cable. Once moisture gets into on end, it loves to wick up along the braid (and even more so with foam dielectric).

Sure would be a shame to climb the mast when the problem is in the bilge ;-)
 
#23 ·
Another thing to try is to connect your emergency antenna to the cable that connects to the mast. You may have to stop at a Radio Shack or some place like that to get a double female connector if you have to interface two male pl259s. If the radio works OK with the emergency antenna connected to the line that runs to the mast, the problem is limited to the mast wiring/connectors/antenna. I saw one installation where a radio tech installed a CB antenna to a marine radio. It worked just about as poorly as yours does.

That one was on a power boat so it was much easier to get to than yours.
 
#27 ·
I have two thoughts that are the easy checks. Check the continuity in the coaxial cable with a standard electrical meter if there is no continuity perhaps you have a problem with your coax or the end connectors or check the squelch on your radio. After that???
Please let me know the solution so I can learn something if this does not direct you to the problem.
 
#28 ·
OK, I finally had a chance to go up the mast and test with the emergency antenna. The E antenna works fine at mast base connection but not at mast head. So, that leaves the coax and connects in the mast the culprit. My best guess is the connector at the mast head is the issue.

The boat yard installed the antenna and coax and it had a very sharp angle (see pic). I tried to pull some slack up the mast but no luck, didn't want to yank to hard. The coax and electrical go through a mesh sleeve inside the mast and I just can't seem to pull any slack up.

So, I'm thinking of making a small, 6" jumper, cutting off the masthead connector and installing a new one there. Then attach the jumper to connect the antenna. Any thoughts?



 
#30 ·
"So, I'm thinking of making a small, 6" jumper, cutting off the masthead connector and installing a new one there. Then attach the jumper to connect the antenna. Any thoughts?"

Sounds like your best plan if you don't want to change the whole coax. However my worry would be water ingress into your inline connection (and hence right down your inmast coax..bad for performance) Could you use adhesive heatshrink around the connection to seal it? That's what they did at the other end of mine, at the mast base. The heatshrink should encompass the inline connector and both plugs mated to it.
 
#31 ·
Sounds like your best plan if you don't want to change the whole coax. However my worry would be water ingress into your inline connection (and hence right down your inmast coax..bad for performance) Could you use adhesive heatshrink around the connection to seal it? That's what they did at the other end of mine, at the mast base. The heatshrink should encompass the inline connector and both plugs mated to it.
Yeah, that's the plan. I'd heat shrink it and I think I saw heat shrink with the waterproof goo in it like the electrical connectors have. Then wrap well with butyl tape.
 
#32 ·
It might work, IF the cable break is in that last few inches. The cable in the pic doesn't look like a problem. I suppose you could go back up, slice off the last six inches fromthe cable, andbring it back down. Then test it for breaks. If there are no breaks--don't evenbother making up the jumper, you'll know the problem is further down the line.

If the coax is in a mesh (like a chinese finger trap toy?) in the mast, that's actually a good way to grip and secure cables. But if there's a cable problem at all, I think I'd personally rather replace the whole cable and not gamble on whether that jumper will or won't fix it. Just a personal choice.

If you do use the jumper, forget the heat shrink and butyl tape. There's a product called "coax seal" or "antenna seal" that is similar to a thicker softer butyl tape, designed just for this purpose. Clean the cable with some alcohol, wrap neatly with coax seal, and you're done. No need for heat shrinking etc. aloft.
 
#33 ·
The close up pic you can't see the bottom of the coax there but it was at a pretty sharp angle. It doesn't look so bad in that second pic as I was able to loosen up a clamp and get a bit more slack in the coax. I'm thinking that's where the issue is though. The radio has not worked since I've had the boat back from them. (next logical Q is why I don't take it back to them to fix on warranty. long answer there but not going back to that yard ever again) So unless the coax was broken while being pulled, the logical problem area is that connection.

Good point on testing the 6" of coax but I figure if I'm up there, might as well just add the jumper. I know replacing the cable would be ideal but I have no idea how to easily replace it with that Chinese finger trap toy holding it (like the description, wish I thought of it :D).

Thanks for the heads up on the Coax Seal, hadn't heard of that, much easier than the melting the shrink wrap for sure.
 
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