On 12 Jan 2015 at 11:11, john@kk9a.com wrote:
> A 55' vertical is not resonant on 40m. How are you matching it? Do you
> have a choke on the coax at the antenna?
>
> John KK9A
Hello, John:
I should have been more clear concerning the antenna. Although it is 55' tall,
it has a combination trap/loading coil at the 33' level.
It was a prototype of an 80/40 meter vertical which a fellow over in
Washington State designed and intended to manufacture, but he died before
he was able to get it into production. I got it in a trade from another ham who
bought it from the estate.
In its original form, it is resonant at both 80 and 40 meters, and is fed at
the
base with 50 ohm coax. The trap/loading coil acts as a trap for 40 and a
loading coil for 80.
I use it on all bands by the use of a home-brew antenna coupler which is
pretty much a copy of a Collins coupler, which is very much like the Johnson
Matchbox.
I can match the antenna to an SWR of 1:1 between the coupler and my rigs
on all bands from 80 through 10 meters, including the WARC bands.
I can also use it on 160 meters by means of a base-coil plus the output
capacitance of the coupler as a series-tuned matching section. SWR is again
1:1 at the station, although tuning is very sharp. Bandwidth is only about 10
kHz between settings on the base coil and adjustments at the antenna
coupler.
On 160 meters, I have worked Europe with it and 100 watts.
I am certain that the SWR on the coax to the antenna is....well....very odd, on
bands other than 80, 40, 20, and 15, but it does work.
BTW, this morning, during my TCC sked with K1NN Jan in Vermont, on 20
meters, at the very end of the sked, it appears as though the jumper between
the rig and my amp (SB-200) either opened up at the shield or shorted. The
SWR went WAY high, and the amp stopped "amp-ing", although the receiver
still "heard".
Sigh...if it isn't something it's something else... :-(
Ken W7EKB
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