Radio Man wrote:
Mark...Can you be specific on what type and/or impeadance of the
transformer you are using? Also what antennas are you using it on?
I mostly use 9:1 impedance matching transformers I wound myself
according to the directions on CW's web site.
http://www.kc7nod.20m.com/new_page_1.htm
On antennas:
#1 is out at the moment because of a lightning strike a few weeks ago
and I've been too busy to get it replaced - but it was a 65' random wire
made with #14 wire that's 225 feet away from my house (and farther from
the neighbors) The coax is underground. It gets practically no RFI.
I'm sure it would work almost as well if it was 60-70 feet away from the
house, but I don't have tall sturdy trees there.
Here's a web site with a discussion of this type of antenna.
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html
#2 is a triangular horizontal loop antenna that's partially over the
house. It was made with about 150 feet of #14 wire. Loops are low
noise designs, but my house is filled with gizmos that cause rfi, so
it's not my favorite. It has a 4:1 impedance matching transformer.
#3 was my first antenna at the house - it's 40 feet of wire stapled to
the rafters in my attic. It's closer to the RFI and I haven't used it
in years. 9:1 transformer.
#4 is my current camping and vacation antenna. It's a 3 meter folding
whip originally intended for a PRC-25 or PRC-77 with a 9:1 impedance
matching transformer that mounts onto a photographic tripod. It works
quite well.
#5 is an Electro-Metrics ALR-25 Loop. I still need to create a control
box to switch bands on it electrically, but ultimately, this may become
the "portable" antenna for places I can drive to where I need to use an
indoor antenna. This has it's own impedance matching circuitry built
in.
I have some extra #43 ferrite's on hand that are a little smaller than
the one CW's design calls for. They work well. If you'd like one, you
can have it for the price of a small padded mailing bag and a couple of
stamps. Contact me directly for details.
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