This thread about SteppIR gain has been enlightening for gain figures
published by antenna manufacturers. I especially enjoyed reading the
enlightening posts from Tom Rauch.
I considered buying SteppIR over the past year, but decided to go with a
stack of 4 tribanders and the SteppIR price tag was just too high. Also I
had the opportunity to compare a Force 12 C-3 against the 3 element SteppIR.
There appears to be little to no gain difference on 20-15-10, but the
advantage of having WARC bands and to be able to "rotate" in seconds is
quite appealing.
Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Gary Schafer
Sent: Wednesday, March 16, 2005 5:09 PM
To: richard@karlquist.com
Cc: W7TMT; towertalk@contesting.com
Subject: Re: [TowerTalk] steppIR Gain--test method
I was looking at the picture and drawing of the test setup on the web site.
They do not show any type attenuator in the drawing.
Even making a differential measurement, trying to read to 1db on a log scale
with 10db per division is not realistic. You just can't "eyeball"
it that close. Especially if you can't switch back and forth between the two
signals. Let alone giving tenth of a db gain specs out of those
measurements.
Using the vernier db attenuator on the 141, if it has not been calibrated
the linearity can be off without too much trouble for making those kind of
accuracy measurements. That adds to the error.
It is also easy for the log scale on those to have errors if they are not
properly calibrated. Not saying that theirs was not but who knows.
The biggest error on the analyzer would come from trying to eyeball the same
screen position on the 10 db scale.
I assumed that they used the log scale and not the linear scale, which would
be easier to eyeball for the same spot. But since no attenuator was shown
the log scale would have to have been used.
By the way if you look at the picture of the test site closely on the right
side it looks like a set of large guy wires for a large tower or power line?
Not good for a test range.
My whole point is that giving gain specs to a tenth of a db with a super
test setup would even be iffy let alone all the obvious errors at first
glance here.
73
Gary K4FMX
[snip]
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