George, N4WM wrote:
I use 450 ohm ladder line to feed a 130 ft inverted vee. But, I don't bring
the 450 ohm line into the shack. I stop it at the eave of my roof, where it
is terminated in a 4:1 balun. From the balun to my homebrew tuner, I use a
piece of RG 213, which is approx 10 ft long. In other words, the RG 213 is
all that comes into the shack. The 450 ohm ladder line is about 65 feet
long and the apex of the inverted vee is about 70 feet up.
This setup gives 1:1 swr, for all practical purposes, on all bands except
160, and works great on 75-80, 40, 30 and 17 meters. I have monoband beams
for 20, 15 and 10 meters, so can't vouch for those bands as far as
effectiveness is concerned when compared to coax fed dipoles.
-----------------------
You've found a good compromise, not using that system on 10 and 15 meters.
That's where that 10-foot length of coax can be quite lossy - perhaps as
much as 0.5 dB to 1 dB per foot of coax on 10 meters with the high SWR's
that can appear there with such an antenna. But down on 80 or 40 that same
SWR may produce only a fraction of a db loss for the whole coax run.
If you used a 1:1 balun (or no balun at all, just some ferrite beads stop
currents from flowing on the outside of the coax) you may find it would load
and get out FB on 160. The impedance on 160 is going to be very low, and
that 4:1 balun is dividing it even more!
Ron AC7AC
_______________________________________________
Elecraft mailing list
Post to:
[hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help:
http://mailman.qth.net/subscribers.htmElecraft web page:
http://www.elecraft.com
Locked
