[TowerTalk] Is there a good 1:1 Balun for a Beam

[Jim Thomson]

Date: Wed, 26 Nov 2014 10:25:07 -0400
From: Herbert Schoenbohm <herbert.schoenbohm at gmail.com>
To: towertalk at contesting.com
Subject: [TowerTalk] Is there a good 1:1 Balun for a Beam


Having ready all the problems with various baluns that rate from junk to 
near junk I have been using the coiled cable to feed most antennas that 
require a balanced feed.  I would like to hear what is the best 
available for a reaonable cost and design for a beam feed. Your views 
would be appreciated.  I have used the BN-86 for years but in fears of 
failure due to rumors that I have heard, I have move it over to a 40 
meter sloper.


Herb Schoenbohm, KV4FZ

##  For folks with monobanders, a physical  1/4... 3/4...5/4 wave of coax,from
feedpoint of yagi..heading back towards the tower, with braid well bonded to top
of tower may well work.  Then you wont require a balun at all..   The Z at the yagi
will be very high.   I have not tried this..yet.  Others have though, with great success.
I don’t know if the tower height plays into all of this.... nor how well the base of the
tower has to be grounded.   Id assume at least 2 rods and better with 3... like 8 ft
copper clad rods... jack hammered into the ground.  Then 2 ga bare cu wire cadwelded
to the rods.  Crimped lugs and bolted to the 3 x tower legs.   Bonding between yagi boom and mast
would have to be good,,and ditto with  mast to tower. 

##  The same technique has also been used with good results on 6m and higher freqs.
5 ft of coax is not long on 6m band....and the braid could be bonded to the boom. 
What else has been used is a 50 ohm line section, made from cu and al tubing..and
sometimes brass, .25 wave long... and bonded to the boom.  The end of the 50 ohm
line section has a female  coax fitting on it.  Then your favourite 50 ohm coax is simply
terminated in the mating male plug..and plugged in. 

##  A bead balun for 6m-2m,  220, and 440 mhz  would also work.  I don’t know what
material is used on those freqs though.   Type 43 large beads works good on 6m, but don’t
know if type 61  would be more suitable for 6m and higher freqs. 

Jim   VE7RF
know about.3hat