On 11/29/2010 7:50 PM, Rick Karlquist wrote:
> Roger (K8RI) wrote:
>> In my case I use center fed half wave dipoles on 75 and 40. To cover
>> the entire band in either case requires a tuner at the antenna (best but
>> most difficult case) or one in the shack (easiest). The same is true for
>> the half sloper on 160. By far the most practical approach is the tuner
>> in the shack. It's what I have and I've never bothered with measuring
>> Roger (K8RI)
> Instead of a tuner, I have a relay at the feedpoint that switches
> in a series capacitor to operate at the high end of the band.
> I use about 250 pF on 80/75 meters. Works for me.
That would work on the 160 half sloper, although I'd need at least 3 or
4. On 75, the center fed, half wave slopers have a feed point that
already sages due to the weight of the feed line, let alone a relay (or
two) and control line(s) <:-))
A tuner or tuners at roughly 25 or 30 feet with ladder line to the
dipoles. Maybe a good project for when I get every thing else done.
The current set up seems to work well over about 50 KHz of 75, and about
100 KHz on the 40 meter antennas with out requiring retuning of the AT5K
or the amp. As both the 75 and 40 meter antennas can be raised and
lowered with halyards they are easy to work on.
I had very good luck with the way the AV640 worked at 40 feet with the
exception of the paper wasps getting inside the tuning unit. and then
the center pin of the coax giving a poor contact, but compared to the
half wave sloper the results were good. Some times it was well over an
S-unit better and some times the sloper was a good S-unit better. Maybe
I should concentrate getting the back up antenna going right after the
tribander.
This was so much easier when I was able to do a lot more climbing
without having to depend on help.
My wife tells me all the help I get is for the times I used to climb for
every one else.
Actually I can still climb, but just don't have the stamina for staying
up there long enough to get all the finishing touches on. My *biggest*
problem seems to be my climbing harness has shrunk.<:-)) Not much, just
enough that extra clothes for even chilly WX make it a tad snug.
73
Roger (K8RI)
> Rick N6RK
>
>
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