[Lowfer] WE2XGR/5 finally hits the air waves!

[Bill Ashlock]

Gentlemen,
 
Last weekend I was able to brave the average 3' snow depth at my property up in Ellsworth, NH, dig out the lost RF and control lines from under the snow, and run my first TX loop tests in the 500K band. This loop is a typical 200' perimeter tree-supported Ashlock loop with 3/8" Cu tubing as the conductor that is pointing N/S. The Rac at resonance measured to be approximately 1 ohm and I feel this is not too bad considering it was a damp foggy day and the clearance between the lower portions of the loop and the snow was less than 4'. The loop-mounted final (yes I'm still a Lowfer at heart :) was able to support over 25w for this initial test but should be able to go to 100w at the 50v Vcc with a change in the turns ratio on the coupling transformer. The efficiency of the MOSfet class D final is near 100% so no cooling is needed aside from the large protruding fins on the side of the water-proof enclosure.
 
Right now I'm in the process of putting the final touches on the exciter and should have it ready for the next trip north this weekend. This is a simple divided-down microprocessor xtal frequency source plus a VFO, a K-ID2 keyer, and a IXDD414PI MOSfet driver for the 200ft of 75 ohm line going to the final out at the loop. I believe my assigned frequency is approximately 507K (It's been a while since I've looked this up :) but I am also planning to do some loop testing in the 513K area of the band in order to keep from interfering with the rest of the group. I'll be sending WE2XGR/5 or just /5 at QRSS 3 but breaking off every 5 min or so for a 10 WPM WE2XGR/5. 
 
Oh yes, I'm still looking for a resonating capacitor for the loop. The enclosure is only able to house a single Cornell type F2 (mil CM70) mica transmitting cap. (approx 1" X 2" x 3") As the result of last weeks test the capacity required turned out to be 1000pf, not 1200pf. Again I'd like to thank the person that sent the two 2000pf F2 caps because this allowed me to operate at 513K last weekend (one inside and one outside in the rain). If anyone knows of an available 1000pf, ~5KV mica cap with these dimensions please let me know. The only one I've been able to find in two days of search is an F2 from Nebraska Surplus Sales for $95.
 
Hope to hear from you guys when I get on the air with some regularity. I think these loop antennas need some more air time to see how well they perform at 500K.... and particularly from a mountain location having very poor soil conductivity.  I'll post a more definitive schedule when I'm fully operational.
 
Bill Ashlock