[TowerTalk] 80 meter quad loops

ersmar@comcast.net ersmar at comcast.net
Fri Nov 4 12:31:24 EST 2005


     I believe this month's issue of QST (Nov) features a wire Yagi for 80M that uses coax on the outer elements to switch from director to reflector as required.   A short length of coax is permanently connected to provide capacitive loading to make the element a (shorter) director; a second length of coax is switched in via relays to lengthen the stub to provide inductive loading to convert the element into a (longer) reflector.  The DC lines to the two relay housings (large-ish PVC tubing and caps) are choked with torroids near the center coax feedpoint.

     Sounds like what you need?

73 de
Gene Smar  AD3F

> For the last few years I have been using four sets of rope supported quads..a 
> two element facing JA, a two element facing VK, a two element facing SA, and 
> a four element facing EU.  All are tuned for the SSB part of the band.
> To operate CW contests, I lower the ends of the ropes supporting them screw 
> in the extra pieces of wire, and raise them again.  It's a pretty simple method 
> but it doesn't solve the day to day excursions into the CW band.
> The loops are actually flattop delta loops so the pointed end faces toward 
> the ground.  The ends either have coax at the bottom or a rope at the bottom to 
> keep it from blowing around.
> So what I would like to do is to put a relay and a coil at the bottom of each 
> element to make the element resonant around 3725.  They are currently 
> resonant around 3775.
> Any idea of what kind of inductance would be required to make this happen?  I 
> know I would need to choke the relay wires.  Would the old "coil it up" 
> method work on the relay wires?  Any special caveats on using this system?
> The system kicks butt on 80, but I would like the ability to switch back and 
> forth between SSB and CW.  Just using a tuner doesn't work, since the 
> reflector isn't a very good reflector when you go down 250kHz.  Any ideas?
> Bill K4XS
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