Tony,
Thanks for the great tip !
I have a single delta loop for 80 with the same configuration tuned for CW.
For some time I have been
trying to figure out ways to switch in and out a section of wire in the bottom
leg so I can switch
between SSB / CW. This will really simplify it, I'll add more wire and
retune it for SSB
and just connect / disconnect the one loading wire ! I have some small HV
vacuum
relays I'll try one for this and see how it works.
great idea, thanks!
Bob
K6UJ
On Nov 4, 2010, at 6:14 AM, Tony Brock-Fisher wrote:
>
> For many years I have used a pair of vertically polarized delta loops in a
> phased configuration on 80 meters. These have performed very well. Each loop
> is approximately an equilateral triangle, apex up. The base is parallel to
> and about 6 feet above the ground. The feedpoint is ¼ wavelength from the top
> which gives the vertical polarization. One issue I have had to contend with
> is setting the frequency for SSB or CW. Each year several times during
> contest season I would go out and insert or remove a section in the bottom
> leg to change the length and resonant frequency of each loop.
>
>
>
>
> This year I figured out an easier way to adjust the frequency of the loops. I
> tuned them for the SSB portion of the band. To lower the resonant frequency
> for SW, I simply attached a length of wire to the center of the bottom of
> each loop. About 10-12 feet was enough to get the frequency to the CW portion
> of the band. The stubs can be left to hang down, or the can be suspended so
> they are parallel to the ground. This approach does not require loosening and
> re-tightening the supports for the base leg.
>
>
>
>
> -Tony, K1KP
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