Hi Steve,
Can't help you with a distributor or even a manufacturer, but my best home-
brew 4:1 baluns have been those recommended by Roy Lewallen W7EL -
see the ARRL Antenna Compendium #1, "Baluns: What they do and how
they do it", particularly pages 163 and 164.
I've built and tested many types of 4:1 balun, air-wound trifilar, bifilar on
ferrite rod, and toroidal, getting good results with all of them - using an
antenna analyser, resistive load. However, using even our modest power
limit (150 watts) I managed to smoke most of them when the loads were
reactive, which is most of the time. The only one that didn't fail (or even
get
warm) was W7EL's 4:1 current balun.
Using only RG-58 on two 4" diameter PVC waste pipe formers, placed at
right angles to each other, I coupled a 300' run of nominal 600 ohm line to 50
ohm coax at the base of a 60' tower, to feed a Force 12 C3 - this was after
melting the insulation on the windings of several different baluns.
Adding the 40 meter dipole to make a C4, I used two separate W7EL baluns
and a large relay to select the appropriate baluns - the 20/15/10 unit is 4
turns of RG-213 on two 6" diameter forms, and the 40 meter balun is 6 turns,
same arrangement. Most important to place the formers at 90 degrees.
At the shack end, I've tried balanced 'L' network tuners with baluns on either
input or output sides - best results for me, measured by both antenna current
in the 600 ohm line and field strength at >1 wavelength from the antenna is
the old balanced tuner, or a borrowed Johnson Matchbox which gave the
same results.
73,
Ken ZL1AIH
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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