I finally gave up on trying to find a place to put a dedicated JA Beverage
on my new property and decided to make the existing "East Coast" Beverage
reversible. Instead of using a two wire design, I went with one wire and
feedlines to each end of the Beverage. The long one is about 1/4 of a mile
long - but am using 1/2" hardline, so the loss isn't prohibitive (less than
2 db).
I used a homemade TDR to look at the antenna and can see the impedance
discontinuity at the "end" - which is back in the shack. I can see some
"roughness" corresponding to the Beverage wire and some small blips at the
impedance transformers. I made the transformers out of BN-73-202 cores,
with two turns on the low impedance side and 5 on the high impedance. This
is the first time I have used these cores and they work really nicely up to
30 MHz no problem.
With the far end open, I see a positive pulse on the TDR as expected, and a
negative one with the far end shorted. Putting a 68 Ohm resistor (the
closest I could find to 75 Ohms in my junk box) on the far end yields no
reflection. It is really nice to be able to keep an eye on the system
with the TDR and make sure nothing gets broken.
So far - the results are just as predicted listening to W1AW on 1802.5 and
WWV on 2.5 MHz. It will be interesting to see how it performs to JA this
weekend during the CQ 160 contest. The length of the wire is something
around 800 or 900 feet.
Tree N6TR
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