The One Point Weekend (times two)

by vk3arr

For two weeks in a row, I’ve had a slow set of weekends chasing. There seem to have been a lot less activations in the past two weekends, perhaps due to the ending of the seasonal bonus, perhaps just due to the regulars having to spend some time localised. Either way, not a huge amount of targets to go for, and the few that are out there sometimes being just beyond the capabilities of 40m and a (poorly tuned) OCF dipole. JOTA last weekend also kept 40m fairly occupied. I’ve found trying to chase the VK2 activations seem to be a hop too far for 40m, but hopefully I can hit a 30m contact sometime soon with those activations.

Two weekends back, I managed to get a hold of Brian VK3MCD on Mt Ida for a single point, with weak signals both ways (42 and 41). That was later in the day, and 40m was starting to get pretty average by then. I had plenty of work around the house, so I didn’t bother with the JOTA stations calling CQ, although with an ear half tuned to the radio, “CQ JOTA” sounds disturbingly like “CQ SOTA”. A few times I heard people ask for summit details on or around 7090, or ask if someone was up a mountain, so it wasn’t just me.

This weekend I had plenty of things on, and even though conditions promised to be good, a few flares seemed to wipe out HF and I was only able to make contact with Peter VK3ZPF. He was on Dingo Ridge (VK3/VC-028), another one pointer, and we exchanged 51 signal reports. Peter pointed out it was the first time we’d actually made contact. I’ll admit it didn’t feel that way, but a quick check of the log showed it was true. I think I felt that way because Peter follows this blog. So, good to make contact, Peter, hopefully the first of many!

I’ve also solved two things that have probably been hampering my chasing somewhat. The first is the incessant QRM I’ve mentioned, from an SMPS somewhere in my shack. Having purchased a 4S LiFe 8.4Ah battery, I decided to make contact with Peter using that, as I’d noticed the QRM centred on about 7088 kHz (with about 2kHz wide sidebands). Since the frequency of the QRM seemed to tie in a bit with radio usage, I had a suspicion it was the power supply for the radio causing the QRM, and the switch to the battery confirmed it. It’s clearly coming in through the DC line, as the QRM was completely absent even with the supply on – it’s not radiating from the internals per se. Once the battery was on, a crystal clear band, with no QRM anywhere. Problem 1 solved. I’ll still use the supply primarily, but if QRM is getting in the way, switch to the battery.

The second one was rereading the plan for the OCF dipole (the K1POO variant). It’s design SWR for 40m is an unhealthy 3.6:1, with a very narrow bandwidth, and a reputation for being difficult to tune. Even at optimum tuning, the loss is ~30%, and the adding a tuner, which will help the VSWR but won’t necessarily do that much to efficiency. I had tuned for 20m before SOTA had been an interest, and that left my VSWR at 7095kHz at about 7:1 (!), which makes for a fairly inefficient radiator, even once tuned. I’ve proceeded to cut a dipole for 7090kHz, which I’ll string up soon and give a test run. Hopefully the better results that come from using the right tools for the right job will accompany that!

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