At 02:08 PM 10/27/99 -0400, you wrote:
In general reflection transformers will
>give you much better F/B than simply tying one of the wires directly to
>ground, which is what most people do. At KC1XX we saw a big improvement in
>performance when we changed over to reflection transformer terminations
>(our own homebrew units) for all the Beverages.
===================
I read your post with great interest John.
I have three 1100' two-wire Beverages here plus a couple single wire resistor
terminated Beverages. The two-wire antennas are constructed quite similar to
the ones ON4UN showed in his Low Band DX'ing book. I wound my own torroids and
the swr at the antenna port to the shack is very low across the low bands. I'm
pretty sure the impedances are close as I was able to resistor terminate the
units with the calculated values and the swr was fine on the test bench as well
as installed. I terminated one of the wires at the far end on each two wire
Beverage to a decent low resistance ground network. Similarly, the feed point
ends are well grounded.
The reflection transformer idea was something I wanted to implement at first,
but it was easiest to just ground one of the wires. They perform really well as
far as I can tell. However, the possibility of making them even better is
really getting me interested in the termination alternatives again. Where can I
get the pre-made reflection transformers?
I've noticed that all three of my two-wire Beverages act similarly. In one
direction on each the signal levels are significantly higher. That is, in the
direction opposite the feed end on all three I notice higher signal levels than
from the other direction. I'm not sure if the grounded wire or the un-grounded
wire is delivering the most signal. Both seem to have decent F/B and signal to
noise ratios but I'm thinking that may be a symptom of something not quite
optimized. Problem is, I don't know which of the many variables it would be. Do
the Beverages you installed with the reflection transformes deliver roughly
equal signal levels to the radio?
Anyone else out the notice their two-wire Beverages delivering unequal signal
levels?
73,
Bruce
AA8U
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