W7IUV wrote:
>The Beverages themselves don't couple. You can see
this in close spaced staggered end-fire arrays. The
source of trouble is the vertical downleads and a
common ground. By eliminating parallel downleads and
ground connections on the unused wires, you can
minimize any coupling.
I've had similar experience Larry. My first
Beverage system (W0ZV in CO) used 7 terminated wires
fed from a common point. Like you, I used one
transformer with SPST reed relays switching the
high impedance output of the transformer to the
Beverage wires. Instead of feeding at ground
level, my feed point was about 6' above ground
with a common ground connected to the low side of
the high impedance transformer output. I used
an isolated transformer winding so the high and
low impedance grounds were separated. My coax
was not grounded at the feed point and simply laid
on top of the ground until it got to my shack
about 200' away where it was grounded via the
station ground.
Ideal?...no. Theoretically sound?...probably
not. Effective?...yes. I was #7 worldwide in
ARRL's DXCC Yearbook rankings when I left Colorado
in 1993, won CQ 160 CW SOHP for USA Zone 4 every
year from 1986-1993 (including 3X #5, 1X #7 and 1X
#8 USA overall) and was never beaten by any local
Colorado multiops, some of whom used 4-squares.
The above system was my only receive antenna during
this period (although I did occasionally use a dipole
for high-angle TX and RX).
One other useful thing this approach allows
is paralleling multiple Beverages simultaneously.
I have no idea what the patterns looked like (besides
the 3 dB impedance mismatch loss) but I found this
system was quite useful in contests for listening in
multiple directions simultaneously.
73, Bill W4ZV
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|