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Author Topic: 102-inch whip and SGC Tuner Tests  (Read 2353 times)
AA4PB
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« on: July 14, 2003, 08:02:33 PM »

I ran some tests tonight comparing 102-inch stainless steel whip, a 75M Hamstick, and an SG-307 whip using an SG-237 tuner installed in the bed of my pick up. The antennas were on a stake-pocket mount with a 3-inch long Delrin base insulator. The feed wire between the whip and the tuner is about 6-inches long and well separated from anything conductive. All tests were run on 75M listening to a carrier from a broadcast station that typically ran about an S4 on the meter. The whips were attached with a Hustler quick disconnect fitting so that I could interchange them rather quickly to make comparisons. The tuner was always re-tuned to match the whip I had attached.

The 102-inch whip and the 75M hamstick performed exactly the same. No detectable difference in received signal strength. The SG-307 was 1-2 S-units lower.

I also ran some tests on 20M, comparing the 102-inch whip to the SG-307 and found about the same difference between them that I did on 75M (perhaps a little less).

The bottom line is that there is no detectable performance difference between a 102-inch whip and a 75M Hamstick when using a properly installed SG-237 tuner on 75 meters.
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AC2RC
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« Reply #1 on: July 15, 2003, 08:06:51 AM »

"received signal strength" ? there shouldn't much difference there. But there should be, as I found , a major difference in transmitted signal. Try it.
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K0BG
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« Reply #2 on: July 15, 2003, 09:23:53 AM »

Actually, these tests have been made and published in the various issues of the ARRL's Antenna Compendium series. All factors being equal (physical length, mounting location, etc.) the difference between an antenna with a centered coil and an autotuner setup (basically base loaded) differed by less than 2 db sometimes favoring one over the other. None had a clear advantage.

The biggest difference has more to do with proper mounting, proper installation, minimizing gound losses, and proper matching (center loaded units).

And think about this for a moment. The most popular type of antenna these days is the screwdriver design. For all practical purposes, they are base loaded.

Alan, KØBG
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KA5S
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Posts: 229




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« Reply #3 on: July 15, 2003, 09:31:48 AM »

>. the screwdriver design. For all practical purposes, they are base loaded. <<

Not unless they're mounted upside down.  Mine are top loaded - I use top hats and not whips.

And no one will persuade me there was just a 2 dB difference between my AH-2 and the Texas Bug-Catcher that replaced it for 80 meters.  I know better.


Cheers!

Cortland
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AA4PB
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« Reply #4 on: July 15, 2003, 03:11:53 PM »

Come on now - you are saying that the antenna loss in dB is considerably different on receive than it is on transmit? I don't think so - not unless you've got something breaking down or arcing over. If that were true then an antenna would be more efficient at 10 watts than it is at 100 watts.

You may not notice a difference in "readability" on receive because the band noise drops by the same amount as the signal so the S/N ratio stays the same. However, if the transmit signal drops by say 3dB then so will the received signal and you will see the difference on the S-meter.
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AA4PB
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« Reply #5 on: July 15, 2003, 03:27:23 PM »

Alan, you are of course correct. My intent however was to see if I could verify the recent claims made on several news groups that a 102-inch whip is useless on 75M and that replacing it with a Hamstick made a major improvement. Although I doubted it, there was the possibilty that the tuner had so much loss on 75M that moving the loading out of the tuner and into the antenna (even a lossy Hamstick) would be an improvement. As the tests show, there is virtually no difference in performance between the two.

I don't doubt that those making the claims actually saw that difference but I expect it was due to an improper installation or the limited range of the particular tuner they used rather than a basic difference between base loading with the tuner and center loading of the Hamstick.
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K5TEE
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« Reply #6 on: July 15, 2003, 04:13:18 PM »

K0BG Said:"the screwdriver design. For all practical purposes, they are base loaded."

This is Totally WRONG!
A screwdriver antenna is a CENTER loaded antenna when used with a whip. A screwdriver antenna is a TOP loaded antenna when used with just a top hat.

Tom
K5TEE
 
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KC9ANQ
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Posts: 8




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« Reply #7 on: September 14, 2005, 05:25:38 AM »

Does anyone know the article names to search for this information? I just bought a Yaesu 857D and the FC-40 tuner and want to install either the 102 inch stainless whip or the SGC SG-307. But if the 102 inch whip will perform the same I will go with it,,,,,,,,easy to figure,,,,,,,

102" whip $18.95
SG-307 whip $265.00
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