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Old February 7th 06, 05:51 PM posted to rec.radio.amateur.antenna
hasan schiers
 
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Default Verticals versus Horizontal Dipoles

Hi Roy,

MFJ makes a nice 81 dB step attenuator for a very reasonable price (about
$70.00 as I recall) for those who don't want to build. In either case (build
or buy), one still has to know how to make good use of it, which to my
experience is more demanding than either pocket book or soldering solutions.

There are a LOT of neat things one can do with a 2 position switch and a
step attenuator. For one thing, a lot of myths can be summarily dismissed
(after getting enough data points...another problem that gets lost in the
shuffle). One simple measurement on anything sky-wave based is completely
meaningless. Things like path-length, time of day, etc. need to be "washed
out" or "isolated" in order to come to anything even resembling a meaningful
conclusion, and one is likely to arrive and multipe conclusions based on the
array of variables one investigates. A step attenuator is an absolute
essential for anyone who plays with gain antennas or wants to compare
antennas. If expense is an issue, you have provided a great solution,
otherwise, the MFJ works rather well for not a lot of money.

73,

....hasan, N0AN

"Roy Lewallen" wrote in message
...
Mike Coslo wrote:
Roy Lewallen wrote:


A step attenuator which is completely adequate for HF and can easily
resolve 1 dB can be made from a few cheap slide switches, some PC board
material, and a handful of ordinary 5% quarter watt resistors. Detailed
instructions can be found in numerous sources, including the Web -- a
Google search brought a large number of hits, the first of which was
http://www.arrl.org/tis/info/pdf/9506033.pdf. But I'm afraid that this
level of homebrewing is beyond the interest if not the ability of the
majority of today's amateurs.



Got it - Thanks, Roy!

- 73 de Mike KB3EIA -


You're very welcome.

The reason for my rather grumpy comment at the end is that I've
recommended countless times for many years that people interested in
evaluating antennas build a simple step attenuator -- an evening project.
It allows you to make direct, quantitative comparisons between two
antennas -- yours or someone else's, as well as calibrate your "S" meter.
But to date, I've never gotten an iota of feedback that a single person
has actually taken the trouble to build one. Rather, they continue to
debate, ad nauseum and without any meaningful data, whether one antenna is
better than the other, or at best quote differences in "S-units" read from
their meters, without the foggiest idea how many dB it might represent or
how different it is from someone else's meter (or from the same meter on a
different band or a different part of the scale). The conclusion I've
reached is that A) Hams would much rather argue than actually determine
the facts, or B) The vast majority are unable to build a homebrew project
consisting of slide switches, circuit board material, and resistors. I'm
afraid both are probably true.

Maybe you'll be the first to actually build one. If so, please drop me an
email and let me know -- it'll make my day!

Roy Lewallen, W7EL



 
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