Success. After my failed first attempt I untangled all the leads, ditched the USB hub and tried a 1:1 unun. With the FT818 set to 2.5W I managed a QSO with a DK at about -13. The wifi was struggling for the Mac to load pskreporter so had to try that once back in the house, but it shows it is getting out ok. Not too bad for 2.5W into a Diamond HF40CL on the car roof parked next to the house. Hopefully this bodes well for an excursion and possible attempt at activating a POTA.
No ferrites on the antenna lead plus one on each USB lead. I did not take those off to experiment as they are not in the way anyway.
Getting dangerously close to being portable… after having wired a cable for the Signalink (I have three now!) because the Yaesu cable is always out of stock everywhere and realising that the FT818 was set for RTTY as digital, not User-U, which is why it would not decode any FT8, I have all the bits ready except for a power pack. I do have a lead for the car, and a 40m whip antenna and magmount.
The antenna is 2.2m long – don’t worry it won’t be used mobile, just put on the car once parked up!
It all works with wsjt-x on the MacBook. So, I have just two things to sort out (apart from the power pack); how to stop the 6-pin mini DIN plugs falling out whenever they want, and why the MacBook only manages about 20 minutes on battery. While that is long enough for a few test QSOs I really want longer. Unfortunately it’s not actually mine so I can’t just replace the battery. Maybe an inverter, which I bet would wipe out the band… the car (electric) only has a tiny 12V battery sufficient for short periods of electronics and to ‘start’ the car, so for prolonged use the main battery needs to be on (i.e. the car switched on), and I bet that will also produce a load of hash.