AD5VJ Bob wrote:
>
> "How do you know the transformer is really working, sure your hearing DX you
> didn't hear before, but is it working like it is
> supposed to."
>
Some use impedance bridges like the MFJ unit to determine matching
characteristics and can do so over a large range of frequencies. But in
the performance department I use the simple and inexpensive means of
monitoring AM stations. This is an easy way to get some general idea on
Beverages by using AM stations during the day. A station listing is
available via the FCC.gov website in the Media Bureau section. Keeping a
log of the signal over noise or just plain S meter readings with
stations on the front back and sides of the Beverage will give you some
good ground wave constants for A B checking transformer performance. It
is a good place to start and also a useful trouble shooting tool
especially with stations in the 1500 to 1700 Khz range. I have
situations were stations to the NW of me in Puerto Rico disappear when
switching to the reverse port of my DXE two wire Beverage and an
English language station in the Lesser Antilles appears and is just a
strong as the Spanish station was in the forward direction. My rule of
thumb is that good front to back such as this on a Beverage would tend
to indicate it is working like it should. In some parts of the states
you can listen to 3 or 4 stations on the same frequency clearly by
switching around your multiple Beverages. It is a test I do all the
time and it has led me to discover all sorts of problems like blown
termination resistors and even animals eating away the shield of one
long RG-6 feed run.
Herb Schoenbohm, KV4FZ
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