Sadly, on a couple of rigs this seems to peak too high in the band. From past experience adding a large capacity across the 50 ohm winding transforms to a much smaller capacitance across the secondary winding. So, I would have expected the resonance point to have shifted LF. I tried a 220pF across the 50 ohm winding but I could not detect an LF shift! The last thing I want to do is alter the antenna itself. At the moment I am puzzled. Maybe the capacitance needs to be much larger. I shall try this next.
If made resonant, I was going to try this on 80m WSPR and FT8.
Some years ago I was surprised how effective a ferrite rod could be on QRP TX.
See https://sites.google.com/site/g3xbmqrp3/antennas/ferrite_tx
UPDATE 1105z: I tried 790pF across the 50 ohm winding and the resonance showed no visible change. I suspect Jay has configured this as a vertical Marconi and not as a conventional ferrite loop. The antenna is encased in heat shrink, so I am unsure of his configuration. Both he and I had assumed a "plug and play" situation!
1 comment:
You could perhaps try adding a bit of top loading with some aluminium foil.
Regards,
Martin - G8JNJ
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