Magnetic Loop Update

I rearranged some PVC fittings to my Magnetic Loop antenna to accommodate the new High Voltage capacitor. Here is what it looks like:


Remaining improvements are to cover the exposed copper pipe with heat shrink tubing and replace the metal threaded rod with a nylon rod, add a tuning extender and install some band limit nuts to aid in single band tuning. I operated this indoors today but had no luck on 5W QRP. Had to use the amp to make any contacts at 45W.

I also verified the SWR 2:1 points and they measured 48kHz bandwidth which is a definite improvement over the other tuning capacitor which was more in the range of 70kHz. I also verified that the AA5TB spreadsheet was giving the proper tuning capacitor values. To do this I would tune the antenna to a specific frequency, say 14.200 Mhz. The AA5TB spreadsheet indicates a tuning capacitor of 42.42pF minus 8.2pF of loop capacitance for 34.22pF. I removed the capacitor from the loop and measured a capacitance of 38.5pF.

This confims that the spreadsheet gets me the right values for the capacitor which I will now use to finalize the 40m loop design. A quick trip to Home Depot this afternoon yielded the remaining PVC fitting I need for this version.



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