Towertalk
[Top] [All Lists]

[TowerTalk] Re: Superior 4:1 Baluns

To: towertalk@contesting.com
Subject: [TowerTalk] Re: Superior 4:1 Baluns
From: zl1aih@ihug.co.nz
Reply-to: zl1aih@ihug.co.nz
Date: Sat, 25 Oct 2003 19:04:05 +1300
List-post: <mailto:towertalk@contesting.com>
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.

_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>
  • [TowerTalk] Re: Superior 4:1 Baluns, zl1aih <=