Don't know all the details but I had run across this a while back about how
B&W got started. Never took the time to follow the leads to Electric Radio.
Sure ran into a lot of their T2FD's at various military comm sites.
https://forums.hamisland.net/showthread.php/12012-Interesting-Article-About-Barker-amp-Williamson
Don W7WLL
-----Original Message-----
From: Mickey Baker
Sent: Tuesday, January 05, 2016 8:11 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Barker & Williamson Model AC - 1.8 - 30 Antenna
toss this piece of crap in the trash, buy a copy of the ARRL Antenna
Book,
some #14 wire at the big box store, a center insulator and end insulators
from the Wireman, and make yourself a REAL antenna.
K9YC offers some good advice, but you might be able to repurpose wire and
insulators.
It is really easy to build a good antenna to fit in a somewhat smaller
space than a dipole. Wire antennas are my "go to" first antenna when I move
to a new QTH - which is infrequent. But, for example, I built a 160M loop
supported in 5 pine trees at my current QTH. Total cost was about $300,
most of that for 575' of (insulated flex-weave) wire. To me, it is easier
to use the many designs available and build a wire antenna than it is to
look in all the catalogs or flea markets and find something to fit my space.
B&W has several products with resistors for matching, including their
famous "folded dipole." Is this "cheating?" Not really, it DOES lower SWR
and enable more output from solid state transmitters with "fold back"
current limiting. It also makes the antenna sound "quieter" by dissippating
received signal energy in the resistor!
It appears that B&W's target market is military - that would fit as they
are near Harris, one of the largest military communications vendors. The
resistor design may work fine for military communication with plenty of
power and a calculated use case, but isn't optimum for what we as hams do,
which is largely ad-hoc "weak signal" work. It's not efficient to use your
RF energy to warm a resistor - better if it were radiated.
You can likely make this thing work - but the resistor may be literally
toasted, as someone pointed out. I think K9YC has given the best advice in
this thread, though.
73,Mickey N4MB
On Tue, Jan 5, 2016 at 6:40 AM, Herbert Schoenbohm <
herbert.schoenbohm@gmail.com> wrote:
This B&W Antenna sort of reminds me of the infamous MaxCom antenna feed
which gave a VSWR of less that 2:1 from 1.8 to 30 Mhz sold for a while in
the 70's and 80's. After scamming thousands of hams with these claims the
ARRL lab put the potted matching unit into a X-ray device and learned that
it was nothing more that a series of toaster elements across the feed
point
inside or a dummy load on the end of your coax with some wire attached to
it. The B&W is sort of a throw back of the TF2D military antenna which at
least did a bit more radiating as a folded dipole with a 600 ohms non
inductive resistor in the center of the top wire. Having said that most
any
end fed wire with a resistor to ground at the far end makes for a quieter
antenna on reception in many cases. But again to market such a product
without any clear indication of what it really can do continues to be the
way of many amateur antenna devices sold to the unsuspecting.
Herb Schoenbohm, KV4FZ
On 1/5/2016 1:18 AM, Jim Brown wrote:
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On Mon,1/4/2016 7:47 PM, john@kk9a.com wrote:
All I could find was a sketch so I'm not sure how it works.
John,
From the sketch on the Universal Radio website, I analyze it as a loop,
formed by the wire, the ground rods, and the earth. The clue is that they
tell you to add a wire between the ends if you're putting it on a roof.
73, Jim K9YC
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