An early start for a bit of antenna testing. Dave, Zl1DL, tried a loop on ground (LoG) antenna with a 32dB amplifier added behind the balun. With a 20m long loop, noise level (as an indication of signal strength) was noticeably low on 80m & 40m. The loop was doubled in length and lower HF looked promising with an increased noise level. Despite band conditions being poor, with a dearth of useable signals, a 40m transmission was slightly more readable on the LoG compared with the MPRG SDR. Increasing the loop length by adding both wire lengths together resulted in S9+ noise on 80m & 40m with AM broadcast signals causing massive intermod products! Perhaps a length too far… or a BCI filter might help here. Harry made some measurements with a NanoVNA and the loop feedpoint presented roughly 500 ohms across about 1/3 of the HF band; the 1:9 balun being a suitable match. The photo shows the test configuration of the loop termination with balun and battery powered pre-amplifier.
After Rob, ZL4ROB, set up his 40m endfed approximately East / West, Harry assembled his extremely shortened dipole in parallel, for a comparative signal strength test. Charles, ZL1RKO, on Waiheke reported; only the signals from Robs antenna were heard. To be fair, Charles had s9 noise and after the fact, it was noticed that Harry’s antenna had “oddly” rotated 90 degrees to be at a null to the destination. How could that be? Rob? Rob? Where’s Rob?
Speaking of dipoles, Mark, ZL1MRT, trialed a center loaded dipole for his data transmission development. Set up on the west deck, Mark could reliably receive data from his remote QRP transmission..
The monthly meeting was relatively short with no significant action points. A new member Qing BG4GEK was welcomed. Qing hopes to obtain his NZ Amateur Operator’s Certificate and callsign soon.
Mid afternoon, we had a visit by Janine, KI5WI and Larry KQ4GUY from Virginia. Larry had called up earlier on 5775, but copy from his handheld was not great. So they dropped in for an enjoyable afternoon chat. A bit after 5.00 pm they went to try their POTA luck on HF on the west lawn.
