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Old 07-02-2011, 13:41   #1
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Attaching Antenna Cable to Backstay

How does one attach the antenna cable from the tuner to the backstay? Previous owner had is installed using a strap and silicone I think but that looks very messy. Any tips/tricks?
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Old 07-02-2011, 13:45   #2
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Send a message via Yahoo to Sheriff
hope it helps

YachtCom - Marine SSB insterlation | backstay antennas | SSB ground | Dynaplates | HF Whip antennas
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Old 07-02-2011, 14:18   #3
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That sure looks ugly but I guess it is not a beaty contest! :-) Thank you!
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Old 07-02-2011, 14:22   #4
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When I re-do mine soon, I plan to have the wire go from the deck, to about 8" past where I want the connect up. (This is so it can double back on itself and point down, to keep water out of the insulation).The connect up will be about 3/4 of an inch of my backstay. I will coat that area with Jet Lube semi conductive grease. Then strip enough of the single conductor's insulation to wrap the wire around and around the greased 3/4" section of backstay. Next I would use 3-M's 471 blue plastic tape, which is very stretchy, and wrap the wire I just wrapped around the backstay. I would go around and around getting it tighter and tighter. I would follow this with black RigRap rubber tape as a sacrificial UV layer. Then clean the Jet Lube ooze out with mineral spirits.

The final step, is for the antennae wire, which is connected above the lower backstay insulator, to have 2" stand offs, the rest of the way down. (about every foot) This is to keep it away from the portion of your backstay that is not to be part of the antennae system. I use little 2" long X 1/4" ID sections of PEX type plastic tubing, and LONG skinny wire ties for the stand offs.

Hope this helps, Mark
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Old 07-02-2011, 14:25   #5
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I just hose clamp (very small) the stripped cable to the backstay, then cover it with CoaxSeal to eliminate corrosion, black electricians tape for protection of the CoaxSeal. Same tuner since 1988, replaced the wire connection when rerigged in 1998. I also use wire ties through shrink wrap tubing to make standoffs; replace them every 5 years or so.
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Old 07-02-2011, 14:29   #6
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Here in the USA you can get a very nice copper slotted grounding nut and bolt from most hardware stores. They are used for the external grounding of house ground to a grounding rod. They are available in several sizes so choose one to match your backstay. You simply put the slot around the backstay, put on the bolt and clamp the antenna wire between the stay and bolt head!
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Old 07-02-2011, 14:35   #7
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This is the type of positive clamp to use. The ideas above seem a little weak in this area. The conductive grease might be a good addition. You may be able to find a similar bronze clamp with a separate hole for the lead...I found one once...
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Old 07-02-2011, 14:41   #8
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I can't agree on using stainless or a hose clamp. The grounding bolts are copper and designed for outside weather use without any grease. If the antenna wire is copper or copper plated then the clamping action will seal to the backstay. Will last forever!
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Old 07-02-2011, 14:53   #9
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Come to think of it, I have my radar on the back stay with one of those stainless steel 'pipes'. The previous owner had the antenna cable in that pipe which probably did give the 75mm distance to the backstay. Is that good or is in insanity to have the antenna running free in a stainless steel tube?
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Old 07-02-2011, 15:40   #10
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...Is that good or is in insanity to have the antenna running free in a stainless steel tube?
Very difficult to say. It's not insane. If it works, it works. For safety you should make sure the backstay or tube that the antenna lead runs near is grounded somehow. This is so some poor soul does not inadvertently become the ground path while transmitting.
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Old 07-02-2011, 17:17   #11
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Stainless steel hose clamp, 3-4 layers of tightly stretched scotch 2242 rubber tape (sticky side out), a couple layers of scotch 33+ vinyl tape. Completely seals the connection. Here's one I did that was in service for years. One longitudinal slice with razor knife and it opens right up and still clean and shiney.

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Old 07-02-2011, 17:39   #12
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No shock at backstay

The best way to drive the backstay is a belowdecks attachment to the bottom of the chainplate, if that is accessible. No big worries from corrosion.

Why? Because the "antenna" begins at the drive point of the tuner, not where a wire might attach. If you run a wire parallel to the chainplate and backstay much radiated energy is lost into the parallel metal. At or near a quarterwave frequency the bottom of the backstay has minimum voltage and maximum current. Current creates magnetic field. That is the field that you do not want to lose energy from in order to have the best effective radiated power.

Now for those who are concerned about "shock"; You cannot get shocked by HF you can only get burned and even then you can grab the backstay with max continuous power out (not what you get with SSB modulation, I'm just pointing out the worst case scenario) and not feel a thing. I have done this with 10kW output continuous. If you brush up against the stay at the top of the antenna you can bet a whitish RF burn on your skin. Not likely at the bottom. So, it is not necessary to run a "High voltage" wire from below decks and attach it high up where theoretically someone might touch it.

Most people including so-called experts do not even seem to know the physics about this type of attempt to get a quarter wave resonant drive element comprising the backstay.
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Old 07-02-2011, 18:46   #13
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P.S. if you have a lower insulator just jump around it with the same wire as your stay. Use S/S cable clamps of same alloy and you don't have a dissimilar metals issue and, therefore do not need to tape over the connections. In fact you risk corrosion right where the tape ends and collects dirt. Keep it clean and exposed to air.
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Old 07-02-2011, 19:18   #14
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The best way to drive the backstay is a belowdecks attachment to the bottom of the chainplate, if that is accessible. No big worries from corrosion.

Why? Because the "antenna" begins at the drive point of the tuner, not where a wire might attach.
I agree but I also continued the wire from the chainplate up past the turnbuckle and attached it there too because I was concerned about possible resistive loss in the turnbuckle due to imperfect continuity in the toggle, turnbuckle, threads joints. So there is a couple of feet where the antenna wire, chainplate and turbuckle are physically and electrically all in parallel and act as one radiator. Just did this on intuition and I'm not sure it is a real concern. (No insulator at the base of the backstay and one at the top.)

For about 8' I slid that split plastic lifeline covering over the backstay to keep hands and fingers off but I'll defer to Ricks advice on whether this is necessary.
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Old 07-02-2011, 20:20   #15
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There seems to be much consternation over what is really a trivial problem with parasitic interaction between the feedline and backstay. I'd remind anyone too concerned about it that:
1. it isn't a resonant length antenna
2. for all intents and purposes, the feed is at the output of the tuner,
3. the radiation pattern is different on every boat because of all the "stuff" on sailboats making interaction of the feedline and antenna of very small consequence,
4. you can get a serious RF burn at or close to the feed point as this is essentially a random length antenna being operated over a wide range of frequencies making any generalities about voltage and current at any point moot, and
5. there are as many options for protecting the connections as there are people, most of which are equally effective and none are rocket science..
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