Choking a 1/4 wave vertical.

It's been nice weather of the past few days, so an hour or two has been spent down at the coast.  With virus restrictions much reduced in Wales now, we are all having to get used to the sudden influx of huge numbers of tourists, all of whom seem to believe that the virus has vanished.

I've had a chance to operate some FT8 using my 'go box', with an output not more than 15W and more typically about 8-10W into simple elevated quarter wave verticals. Previously, all of my truly portable work has been with tiny WSPR outputs, or SSB.

T-shirt weather at the coast (IO73vh)

It quickly became apparent that a choke is needed on a vertical used with a computer, especially when relatively close to the antenna, where coax lengths are similar to resonant radial lengths at higher HF (I was testing out 12 and 10m).  Transmitting within about 2 metres of the antenna almost always led to the Raspberry Pi crashing, which it never does when no transmissions have taken place.

Moving to about 4 metres or so from the antenna base usually but not always eliminates the problem, but for future use, I will have to install a few turns of coax, or just a few wraps of coax around a split ferrite.

It's a moot point as to whether the Pi crashes due to common mode current along the coax, or the intensity of the field strength when next to the antenna, or both.  Given that the crashing ceases with a fairly small increase in spacing, I suspect the main cause is simply the field strength at the antenna base.

A little more attractive.  New interior, too!

Meanwhile, general aviation returns as a permitted activity this week, so radio takes a back seat for a while, whilst I throw a (newly refurbished) aircraft around the wet and windy skies of North Wales a bit!