Hi Gerald,
Thanks for the reply. I understand what you are saying but it seems a large
deviation given the number of radials. He does have the radials tied
together with those of the other elements where they cross and I think some
ground rods around every 20th radial or so about half way out.
Maybe they need to be shorter so that they will function closer to ¼
wavelength during the winter??
I have never heard of that much of a change from summer to winter. Then
again maybe no one has measured the impedance during the winter.
Thanks
Gary K4FMX
_____
From: TexasRF@aol.com [mailto:TexasRF@aol.com]
Sent: Monday, March 16, 2015 4:21 PM
To: garyschafer@largeriver.net; jim.thom@telus.net; towertalk@contesting.com
Subject: Re: [TowerTalk] modeling compare: 80M, 2EL vs 4SQ
Gary, just a wild guess: The dielectric constant of water is much greater
than air. Perhaps that makes the radials electrically long enough that the
antenna becomes offset fed and if so, that would raise the impedance.
Sort of like what would happen if elevated radials were .4 wavelengths long
instead of a nominal .25 wl.
73,
Gerald K5GW
In a message dated 3/16/2015 4:10:40 P.M. Central Daylight Time,
garyschafer@largeriver.net writes:
Speaking of radials: a friend of mine has an 80 meter 4 square with 120
radials on each element. They are laying on the ground.
In the summer the element impedance measured right around 37 ohms on each
one. this was with disconnecting the other 3 elements and left floating.
When the snow and ice came the impedance measurement on each was around 67
ohms! Anyone have any ideas why the impedance would change that much?
73
Gary K4FMX
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Jim Thomson
> Sent: Sunday, March 15, 2015 9:04 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] modeling compare: 80M, 2EL vs 4SQ
>
> Date: Sun, 15 Mar 2015 07:03:00 -0400
> From: Pete Smith N4ZR <n4zr@contesting.com>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] modeling compare: 80M, 2EL vs 4SQ
>
> I think both John's and Gary's commemnts square with the series on
> radials that was on NCJ a few years ago. The message I took away from
> those articles is that if your actual ground characteristics are good,
> the improvement with radials, no matter how many, will be quite limited,
> while if your ground isn't good to start with, radials can make a lot of
> difference in the pattern, especially at low angles.
>
> 73, Pete N4ZR
>
> ## 4 sq is wonderful...provide u have real estate to install it all.
> w2pv removed his
> 4 sq since the grnd conductivity was lousy.
>
> ## check out steve, VE6WZ site. He is on a tiny 50 foot wide city
> lot.... and his 89 ft crank up
> tower is only 14 feet away from his side fence. So he made the hb
> 80m, 2 el yagi on a 28 ft boom.
> It only has 66 ft long, half size eles... coil loaded half way out.
> yagi is up 100 feet. He works
> Europe on 80m SSB... like a machine gun. b4 that, he had a f12 80m
> rotary dipole, also up 100 feet.
> Check out his website. These days, with T bar capacity hats part way
> out each side,and tornado
> drives at the center... motor driven compressible .25 inch tubing
> coils...u can have ur cake and eat it too.
> Then the yagi will cover the entire band easily, with max gain /fb and
> flat swr. 10 pre-sets on the
> coils..then manual tune between pre-sets with the digital readout turns
> counter.
>
> Jim VE7RF
>
> _______________________________________________
>
>
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