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Old 25-06-2007, 12:55   #1
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A positive connection to toerail

I am unable to get a positive connection to the toerail (for a rf ground) using the existing thru bolts because of the sealant used to keep water out, the existing bolts are countersunk thru bolts and may not maintain a good connection (because of corrosion) even if l can obtain continuity.
I am considering drilling and tapping for a better connection but prior to drilling thought l would check in to see if this has been done and to what degree of success.
Toerail is aluminium and is not bonded to anyother metal on board. What metal (bolts/machine screws) would you suggest.
Dave
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Old 25-06-2007, 13:58   #2
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Dave:

Toerails are often annodized, which acts as a type of insulation....so you've gotta get through that.

I think what I'd do is the following:

1. Drill a 1/4" hole through the toerail and deck;

2. Countersink the hole in the toerail;

3. Find a 1/4" s/s bolt with a flat head designed for countersinking, and use this to pass through the toerail and deck;

4. Attach a wide copper strip or ground strap to this bolt under the deck, and run this to your tuner ground lug;

5. Use a dialectric grease (tuneup grease from any auto shop) and lightly coat the bolt and the folded-over copper strap, and the s/s washer, lockwasher, and nut;

6. Tighten very securely.

While in some ways a copper or bronze bolt might be better, you won't lose much with s/s and it's stronger and easier to find.

Others may have better ideas.

Be sure to check whether the toerail is broken into sections and, if so, you've gotta bridge them to maintain continuity.

Let us know how you make out.

73,

Bill
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Old 25-06-2007, 14:23   #3
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Bill the toerail is continuous but l have to bridge port to starboard, the existing toerail does have countersunk SS bolts but l think the tapped bolt would give more contact surface.
l had posted last week that l was giong to use copper perferated strapping as a ground to the tuner (18" from tuner) and have folded it over on itself and spot soldered it together so it has more ?heft?
The head of a screw will not be an eyesore and l plan on applying 4200 over it to make it watertite.
Getting close to finishing this project and looking forward to talking with you!
Dave
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Old 25-06-2007, 14:32   #4
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Great, Dave!

Sorry, I missed your earlier post. Was sailing, then traveling. Kids and grandkids!

Let me know when you're QRV.

Bill
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Old 25-06-2007, 20:35   #5
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Dave, I don't think you'll gain anything from doubling over the copper and spot soldering it. For an RF counterpoise you want the greatest amount of surface area, since the AC signal is carried on the "skin" of the conductor. If at all possible, using a wider strap should help. Or, a roll of copper roof flashing (wider still) if you can.

Speaking of which, be prepared for a shock when you see the prices of any kind of metal roof flashing.

All considered...running a roll of flashing below decks and simply keeping the toe rails out of the picture may be more effective. Also makes it harder to get an RF burn from a "live" toerail.<G>
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Old 28-06-2007, 12:54   #6
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Bill;
l established a contact with Austin Texas 1300 miles on 14.300 but couldn't contact a friend aboard his boat in Sault St Marie (300 miles) atmospherics? Am l still "experimenting" with toerail ground or should l look elsewhere for reasons.
Dave
PS
Once l cut through the annodizing on the toe rail l got continiuity on the toerail.
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Old 28-06-2007, 13:10   #7
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Dave-
I would guess your signal skipped right over the local (300 mile) station and they couldn't pick you up. HF can be like that, it has a large local "dead zone" around your own station under many conditions.

If you look up "NVIS antenna" or "NVIS" on the web, you'll see more about this. In order to work locally on HF radio, you would use a totally different approach that sends your signal straight up and bounces it right back down around you, in your local area. Watch out, you'll wind up installing an antenna farm on your boat in order to start covering all the bases.<G>
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Old 28-06-2007, 13:19   #8
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I guess my definition of "LOCAL" needs correction.
So effectively what l was trying to do was almost a line of sight communication.
This radio stuff truly is an education.
Dave
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Old 28-06-2007, 13:26   #9
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Dave:

Hello Sailor is right: on 20 meters, 300 miles is often too close, depending on time of day, propagation conditions at the time, etc.

For communication with closer stations, you'd need to use a lower frequency band: 7 mHz would do it nicely. Listen on 7255 to East Cars for stations up and down the East Coast and, of course, to 7268 in the mornings from 0745 to 0830 for the Waterway Net.

At night, even lower frequencies are required for short-hop communications. For a real hoot, tune into 3898 late evenings and listen to the good old boys network....they spend hours insulting one another...all in good fun.

Congratulations on getting up and running.

Bill
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Old 28-06-2007, 14:02   #10
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Concerning the NVIS...what if.. (Here l go again with the experimenting)...l laid the long wire horizontal at a lower height?
Would that not reduce the output so as to bring in closer stations??Seeing as it is not extending 45' up the mast?
Dave

Or how about a horizontal dipole cut for 7 mhz?
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Old 28-06-2007, 14:13   #11
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Dave-
AFAIK, the optimum height for an NVIS antenna would be 1/10th of a wavelength above ground. Ground being somewhat confusing, since electrical ground and surface soil level may not be the same, and local ground characteristics apparently drive some NVIS users nuts. But over salt water...figure a horizontal dipole for 7MHz (42 meters?) would be best hung at 4.2 meters above ground level, about 12-13 feet ?
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Old 28-06-2007, 14:17   #12
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Dave:

NVIS is more than just antenna. It's most important component is FREQUENCY. The North Vietnamese used NVIS to get from valley to valley, shooting signals almost straight up, then back down. To do this, however, you need to use a very low frequency. It simply won't work with 20 meters.

Forget playing with antennas. If you want longer distance communication, use higher frequencies. For shorter distance comms, use lower frequencies. Also, the shortest hops on any frequency depend on time of day. Daylight, around noon, is the shortest. Nighttime is much longer, with the longest being near dusk and dawn.

Bill
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Old 28-06-2007, 14:21   #13
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So i'm looking at 2metres?(Not an option on my old Yaesu Ft890)
Dave
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Old 28-06-2007, 14:24   #14
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What is it you want to do?
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Old 28-06-2007, 15:22   #15
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Dave-
Catch-22, if you want to speak with your buddy 300 miles away? No, two meters generally wouldn't reach him. VHF tends to be "line of sight" (figure 10-15 miles) and even with repeaters, maybe 75 miles. Unless you get into linked repeater systems and other options.

There are some times when "simple" radio just isn't the answer, because of physics and the limits of how radio waves travel. I think at 300 miles, the answers are for both parties to be using NVIS, or some other "linked" systems that don't require direct radio communications. Or...honest...if you can put enough power in it, you beam the signal the other way and try to bounce it around the globe the long way to him.

Sometimes VOIP and cell phones still can be the simplest way to go.<G>
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