> In light of the horrible QRM in last weekends 160 test I got to
> thinking about a beverage again. I had one here before but
> didn't use any un-un's or anything like that to feed it. I just
> used a small antenna tuner I made, fed a bit of RF into the
> beverage and tuned it for 1:1. What would the difference be
> between using a matching transformer or just building a small
> tuner to tune the beverage. Why do we have to build something as
> complicated as a matching transformer instead of a tuner?
Matching transformers are much more simple than tuners,
broadbanded, and can also isolate the feedline from the antenna
preventing the feedline from being part of the antenna system.
I use a small #73 mix binocular core available from Ameritron (P/N
412-5250). This core requires a two turn primary and 5 turn
secondary to match 75 ohms to the Beverage, or a six turn
secondary to match 50 ohm cables to the Beverage...and as a
transformer will work from a few hundred kHz to over 30 MHz.
I keep the ground for the Beverage TOTALLY isolated from the
coaxial cable. If the shield is connected to the Beverage's ground,
and since that ground is often far from perfect, the shield of the
cable will be part of the antenna system and conduct noise and
unwanted signals into the system. All good beverage transformers
isolate the feedline from the antenna system.
Your tuner has the advantage of attenuating out-of-band signals,
but that is the only advantage.
73, Tom
(W8JI@akorn.net)
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