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Author Topic: Experience with the Tarheel ground radial kit???  (Read 3155 times)
W5JMC
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Posts: 18




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« on: May 28, 2010, 12:31:55 PM »

Does anyone have any practical experience running a Little Tarheel II mounted with the ground radial kit sold by Tarheel? (http://www.tarheelantennas.com/accessories)

I've installed radials for vertical antennas before, and I believe they have to 1/4 wave length for the respective bands.  I recall doing three for each band in a circular pattern in the ground.  Whereas this Tarheel kit looks to be all the same length (ten radials nine feet long each).  Just curious if anyone had experience...

Thanks!

John, w5jmc
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WX7G
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Posts: 6136




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« Reply #1 on: May 29, 2010, 08:46:00 AM »

The Tarheel kit should work well enough. For ground mounting make all the radials the same length. For the Little Tarheel on 40-10 meters 20' is about optimum.

The very worst ground mounted vertical ground system one can have is a few 1/4 wavelength radials. Shorter radials can actually work better. See the N6LF papers on this.

I use a Tarheel 200HP ground mounted with 64, 20' radials. For the Little Tarheel you can use a longer whip for more signal. The MFJ 108" whip will allow your antenna to work 80-17 meters. A 72" whip will work 40-10 meters.
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KG7RS
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Posts: 15




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« Reply #2 on: May 29, 2010, 08:21:31 PM »

Hi John,
In fact I just purchased a new Tarheel 100A, MT-1 mount and the radial plate kit for ground mounting. Before this, I used a 75A on an Alpha Delta Outpost tripod quite successfully before purchasing the 100A.
The Tarheel radial plate is very high quality. It does come with 10 9' radials, very nicely constructed with a good grade of wire that lays flat on the ground and tends not to curl.
I installed my 100A using a 4' long 1" diameter galvanized pipe hammered into the ground. The radial plate is mounted on this pipe with the included saddle clamp and sits flat on the ground. The MT-1 mount that holds the 100A mounts on the pipe immediately above this. My backyard has small river rock pebbles and I buried the 10 radials an inch or so under the rock so they are not seen. How does it perform? Great! Essentially flat SWR on 80-10. Working DX is like falling off a log.

For ground mounting verticals, untuned radials are used. No sense in making them 1/4 wavelength as they will become very un-tuned from sitting on the ground. Resonant radials are generally used for mounting a vertical with an elevated base. In this case, very few tuned radials do great things for the efficiency of the antenna. For a ground mounted vertical you must use LOTS of radials to achieve good efficiency. There was a recent article written in QST where a fellow did a study on the number of radials and the effect on vertical efficiency. Most of the available efficiency gain is made with 16 radials installed. The increase in efficiency is much more subtle the more you add beyond 32.
As far as length of the untuned radials - I read where the length does not need to be longer than the radiator length. So for those of us using screwdriver verticals ground mounted at home - 9' is a good length. I did my own experiments with a Super Antennas MP-1 manual screwdriver antenna. 10' was the magic length. I started with 20' radials and got a poor match on all bands and lousy radiation efficiency. I started cutting them back in 1' increments and watched things improve until I got to 10'.
So, to sum up, the radial plate Tarheel provides is a sound concept. As for me, I plan to add another 10 radials for a total of 20. That should be good enough.
One last thing - the radial plate made by DX Engineering intrigues me as the PL-259 coaxial connector mounts to a bulkhead right on the radial plate instead of having the radial plate grounded to the antenna base solely through the mounting post. DX Engineering says their method is a much better arrangement and it does seem logical to me. I thought about installing a short braid strap from the antenna mount bracket to the radial plate to improve the ground integrity but not sure it's worth the effort. I'd be interested in the experiences of others here.
73, John, KG7RS
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W5JMC
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Posts: 18




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« Reply #3 on: May 30, 2010, 10:26:29 AM »

Excellent -- thank you both for your replies/thoughts.  I think I will pick up the radial plate and give it a whirl for Field Day.

Best,

John, w5jmc
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