[TowerTalk] More Collins Balun Info

Dave Bowker dbowker@shire.sjv.net
Wed, 19 Nov 1997 10:19:04 -0500

The Collins type of balun was derived from the 1/4-wave parallel line balun
which has been around for many decades.  In the parallel line
configuration, it is a narrow-band device and applicable to only a single
amateur band, or portion thereof.  Bill Orr described fabrication of these
in various editions of  The Radio Handbook, dating back to the 1950’s
(perhaps earlier, but my earliest edition is dated 1956).  The second
edition (1 September 1959) of the Collins Radio publication entitled
Fundamentals of Single Side Band had a short section on both the 1/4-wave
parallel line balun and a coiled version of it which it indicated was
capable of operating over a much wider range of frequencies than the
1/4-wave parallel line configuration.  It was this publication from which
the name Collins Balun was coined.  Early editions of the ARRL Handbook and
current editions of the ARRL Antenna Book also describe 4:1 versions in a
section labeled “Coil Baluns” (I have a 1956  handbook that includes it), 
and Barker & Williamson sold a commercial product for matching 75-Ohm coax
to 300-Ohm antennas in the 1950’s which was very popular with amateurs
using Windom antennas and folded dipoles.  The fifth edition of Radio
Engineering Handbook (1959) and first edition of the Antenna Engineering
Handbook (1961), both published by McGraw-Hill, Inc. included a very brief
description of a coiled balun and “type-9” balun,  respectively, which is
essentially the Collins design.  The Radio Engineering Handbook piece is
especially interesting in that it uses a combination of coiled coaxial
transmission line and coiled parallel transmission line sections with
compensating capacitors to achieve a 9:1 (50-600 Ohm) transmission line
transformer balun covering 2-30 MHz and capable of handling “power levels
of a few kilowatts”.

73, Dave

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