Yeovil ARC QRP Convention
Several members of IoAARC travelled in a minibus to Sherbone, where Yeovil amateur radio club were holding their 35th annual QRP convention. A good time was had by all, among us we picked up a couple of rigs, aerials and Matt M3MMZ and Mike M6FCT picked up some kits for the intermediate exam. We chatted to the RSGB representative who would qualify our Scout Hut for holding the exams.
It was a good rally, with a fair range of RF components and connectors with JABdog having a good presence on the stage and another hall with traders, including Lindars of Yeovil.
We listened to an interesting talk “An Introduction of Magnetic Loop Antennas” by Dave Boniface G3ZXX. Dave took us through the tradeoffs of making HF magnetic loops between loop material diameter, loop diameter and loop material. Even driven by 5W the circulating currents could be 30A or so and of course there is a high voltage across the open end at the top of the loop where the capacitance is. That was about 1kV in his example run at 5W. The high currents mean joint resistances need to be exceptionally low. Dave had an example on display made out of heliax. This showed us one method of using the capacitance of the loop ends overlapped. That is one approach to getting a high voltage capacitor with no joints to the loop. The circulating current is lower at the high voltage end but only by about 10% it appears.