First test with this portable magnetic loop on WSPR TX/RX. The loop setup inside the house as you can see. TX with 5W from the FT-817. Results were good after 2 transmit periods. But receive was difficult as I had some QRN from the computer's power supply which (S5-7). Remember my transmit problems lately with my attempt to get on air from the field? Well, it seems when the laptop is not on a power supply it cuts the 5V supply on the USB port. I use that 5V for powering my USB modem. So, I did a separate receive session with the power supply disconnected.
![]() |
| Loop on RX, did reasonable but still had QRN from electronic equipment nearby. |
![]() |
| Loop on TX was a surprise. Best distance with VE3UTT 5880km |
I find the loop difficult to tune. Without a external analyzer of SWR meter it is almost impossible to find the resonance point. However it is almost ideal for use inside the house or if you need a antenna for a small footprint and low heigth. I homebrew this one myself with the help of PE1BVQ Hans and Hans kindly donated a nice 3x500pF capacitor as the hearth of the antenna. Thanks again for this Hans!
It was not my first experience with a magnetic loop, but the way I build this one was very different from the coppertube one.
Update: just when I thought the band was dead and no spots were received anymore on WSPR I tuned into the JT65 frequency. I made 2x1 minute transmissions and left the receiver on till I had to close the station.
![]() |
| Results 20m JT65 with the loop inside the house |
The strange thing is that there was nothing visible on waterfall and nothing was received on the WSPR frequency at that time. Though the JT65 frequency was full of signals.
