Already looked at it. I hate to say it but I'm anti open wire feeders.
Hate 'em with a passion. Every time I've been near one it's caused
trouble. I much prefer coax and a good choke to get rid of common mode.
Typically use your pages that hold a wealth of information, but with the
5 slopers, I see more headaches with open wire than with coax. I'll put
up with a little more loss for convenience. I can still usually join a
pileup and still work the DX on one or two calls, I remember not too
long ago, the station was laughing and said, now there's a ham with
confidence, he only gave his call once, which I had and it worked. I
just listened for a minute or two, saw a pattern after a few contacts,
waited for a lull and gave my call. In most instances, it's timing, not
power. OTOH there are some rock crushers you just wait out.
BTW: They may be over kill, but I think my open, multi core, with
spacing, implementation of your designs will handle the legal limit, key
down, no time limit.
73
Roger (K8RI)
On 6/15/2016 Wednesday 10:58 PM, Jim Brown wrote:
On Wed,6/15/2016 5:32 PM, Roger (K8RI) on TT wrote:
With that set up, it worked well at 200 W, but as I increased the
power, around 1 KW (maybe a little less) every LED in the system lit
up. Instead of hanging more weight at the feed point, I added another
choke with 5 cores and 6 turns ( wound much tighter) where the
feedline reaches the tower. That completely cured the problem up to
full power out.
Hi Roger,
Look at Slide 17 in k9yc.com/7QP.pdf for a bifilar-wound choke
connected as parallel wire transmission line. This is a #31 core. The
choke design is mine, but the slick mechanical design is by Glen, W6GJB.
This choke is good for at least 600W at contesting duty cycles for CW,
SSB, and even RTTY if installed in a center-fed resonant antenna. For
greater power handling, a second choke either in the air or farther
down the line is needed. This choke CAN fry (I've done it) at high
duty cycles of legal limit CW (calling CQ after you've already worked
everyone on the band). :)
The wire is THHN, so Zo is 80-90 Ohms; antennas like the C3SS (which
we really like for portable operation) doesn't like it (I think the
mismatch screws up N6BT's coupling method), but the C3SS works fine if
you wind it with a tightly spaced pair #12 enameled wire.
We did something similar in concept with different hardware in
http://k9yc.com/80M-FDVertical.pdf See slide #26. Designing
conservatively, we used three chokes, but actual operation showed that
two was enough. Our use was with a KPA500 on CW for 7QP.
You asked about an OWA; I've lost track of what OWA is short for. :)
73, Jim K9YC
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