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Old 11 August 2014, 09:55   #1
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VHF antenna on side of A-frame

Have any of you ever mounted their VHF antenna on the side of your A-frame? And have you had any issue when doing so?

My A-frame has a SS cross member half way up each side to hold the two SS tubes together, and the previous owner had the old 1m GRP whip antenna mounted on the port side with a swivel mount. (As in the pic).

Unfortunately the antenna had shattered near the top and the cable from it had been left coiled up inside the console but was corroded, so I ripped the whole lot out.

Due to the lack of room at the top of the A-frame when the cover is on, I may well be mounting the antenna on the side of the A-frame as previous, but would welcome thoughts. I know the ideal position is on top of the A-frame for height, but I literally wouldn't be able to mount a swivel/ratchet mount on top of the A-frame due to the cover being tight and I don't want to cut a hole in the (rather expensive, good quality, bespoke cover). I'd also need to lower the antenna on a ratchet mount (as previous) if I fit it to the side of the A-frame so it will fit inside the cover.

Recommendations for antenna and/or mount would be appreciated, although I have read the various threads on this so it's not essential. It's more thoughts on mounting on the side of the A-frame (or alternatives) that I'd like to discuss here.

Thanks!
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Old 11 August 2014, 10:21   #2
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The Antenna close to a steel object will be affected by it, as you will interfere with the polar pattern and the Steel will act to a degree as a reflector. If you look at TV antenna they have a reflector, active element and a number of Directors.
So in essence your VSWR will be affected and so will your ability/range to transmit/receive in the area of the metal work.
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Old 11 August 2014, 10:30   #3
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Yeah, I didn't really think about that. So I somehow need to get it on top of the A-frame - but with very limited room due to the tightness of the cover (in pic).

If I drill through one of the flat SS ties on top of the A-frame to the P or S of the anchor light, maybe I could mount an antenna there leaving only the screw connector sticking up. My only concern is how susceptible to damage would an antenna be with constant screwing/unscrewing every time I put the cover back on?
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Old 11 August 2014, 11:42   #4
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If you have a longish antenna (mine is a Shakespeare 6', I think) the actual radiating part is tucked away in the top 1/2 to 1/3 of the whip.

I've got mine mounted pretty similar to your pic, though my arch is aluminum, not steel. The only issue I've had is that, when folded down, I have a tendency to run into it when trying to access that side of the boat while on the trailer.

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Old 11 August 2014, 11:50   #5
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That is only true if it's a base loaded antenna !!! at 6' your almost a full wavelength antenna !! doubt very much that it's a loaded one.
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Old 11 August 2014, 11:57   #6
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How about using a short extension pole on a ratchet mount, to get the antenna above the A frame. Glomex do a range of extensions & good S/Steel ratchet mounts.
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Old 11 August 2014, 12:20   #7
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Quote:
My only concern is how susceptible to damage would an antenna be with constant screwing/unscrewing every time I put the cover back on?
we have a Metz mounted on top of the A frame as you describe. The coil and antenna is unscrewed every time we put the boat back in its garage in order to clear the door frame and that amounts to a lot of times during a year. We have had no issues doing this. We did lose a few rib raider antennas in the past but so has almost everyone and doubt it had anything to do with taking it off every time it was garaged.
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Old 11 August 2014, 15:49   #8
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Which Metz do you have? Is there any chance you could take a photo of how you've rigged it? No worries if you can't. Thanks for all the replies so far.


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Old 11 August 2014, 16:28   #9
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search Salty John on t'interweb. He also turns up on here now n then.
The normal Metz on there with the red bit at the base (technical description eh!)
Rigged with hole in flat horizontal plate at top of A frame with the screw connector thru this hole (get extra nut off Salty to fix screw threaded bit in A frame). Wire is inside A frame n pops out near the mouting point. Simples.
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Old 11 August 2014, 17:33   #10
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Ah right, yeah I've seen the antennas on Salty Johns but wasn't sure which of the two you meant - I know now.

Sounds simple enough, do you ever get issues with water/condensation getting in the open connector while towing or do you put the antenna on before setting off?




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