I will mirror the experiences of those who have tried feeding ladderline-fed
antennas in the shack with unbalanced matching networks employing a balun
either at the input or output. It may provide reasonable balance on the lower
bands, but as you move up past 10mHz, the currents on both feeder wires become
progressively unbalanced, leading to RFI problems such as K3EY experienced.
In my experience an inherently balanced, link-coupled network like the
venerable Johnson Matchbox has proved to be the answer, assuming that the
antenna flat top was in the clear away from large objects and the tuned feeders
were brought away from it at something approximating a right angle for a
considerable distance.
I recently sold my KW Matchbox and learned of a ham in the Pacific
Northwest who, for fun, hand builds balanced matching networks using
essentially the Annecke design, with variable link etc. He builds both an 800
watt version and high power models and can include rf ammeters or SWR bridge
integrated into the box if so desired by the customer. His prices are very
reasonble and the quality of workmanship is superb. His call is W7RQT, Pat, a
retired engineer, and you might look him up and email him to ascertain if is
still building his wonderful balanced matching networks.
Vince K7NA
Date: Sat, 9 Jul 2005 09:58:23 -0700
From: "denton" <denton@oregontrail.net>
Subject: Re: [TenTec] "Radiates like Crazy"???? No
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Message-ID: <004d01c584a7$6b48b8a0$0200a8c0@VIVSDENTON>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I have also switched back and forth from running Johnson Matchboxes to ant
tuners with baluns to feed ladderline, and can votch for the below.
Currently running a pair of those old Matchboxes to feed vertical and
horizontal dipoles with good results.
Is any European manufactures now building true link coupled balanced line
transmatches?
Would dearly love to secure an Annecke on this side of the pond...
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