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Topband: Measuring FS comparing antennas

To: "Dan Edward Dba East edwards" <dan.n.edwards@sbcglobal.net>, <topband@contesting.com>
Subject: Topband: Measuring FS comparing antennas
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Tue, 25 Sep 2012 10:26:02 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I thought about this, and thought I better add more. I didn't mean to imply someone has to have a selective level indicating instrument to measure things. I was only pointing out what I typically do now.

I looked on eBay and I see the thing I bought in excellent shape for maybe 100 dollars or less is now selling for several hundred dollars or more. I find deals because I am "tuned" to watch for selective level meters that cover frequencies I am interested in.

With only a power meter and a relative field strength meter, we can do an accurate comparison which is limited by the accuracy of the power meter and consistency of the field strength indicator. This would not work on sky wave or extended ground wave.

With an attenuator pad, S-meter, and a "pinger", we can do pattern and gain comparisons.

When I initially set my four-square up, I used a pinger. It was an 1843 kHz pulsed crystal oscillator in a box with battery and whip antenna, and I had enough roll out radials to make the signal level stable. I looked at a map and placed the pinger where I wanted a null or peak, and I used an attenuator and always set the S meter to exactly the same level.

I could check pattern and gain that way.

The results of that wound up being within 1/2 dB of what I obtain with much better instrumentation.

If a Ham thinks about a measurement problem for a while, there is usually a way to directly measure something without spending a great deal of time or money. This is a whole lot better than depending on feelings, especially on a band as fickle as 160. After all, the people who came up with the physics behind all of this stuff were almost perfectly accurate, and they did that long before anyone knew what an S meter was. :-)

What we really need is an article, or more effort, in learning how to compare things in a way that has some value. Otherwise things become a Gotham antenna advertisement, or a Jim Jones cool-aid party, and we really don't know if things are better or not.

73 Tom
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