[TowerTalk] Delta Loop Tuning Tip

[Robert Harmon]

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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