Well I have found what is causing the false triggering.
Rather than build an RF sniffer i decided that I would walk around in my shed with my handheld radio scanner testing at the frequencies commonly used for wireless alarm systems (bonus discovery so my radio scanner still has a use after all). Tuned to 315 Mhz it quickly found this:
https://www.repco.com.au/en/product-...tarter-2400amp , my Repco 2400 Jump Starter, emitting a strong signal from 310Mhz to 315Mhz and slightly beyond. Even at 5Mhz their RFI albeit not as strong. This is with it NOT plugged in and being charged just "passively" (or not so much it seems) sitting there. It is a bit too heavy and bulky to relocate into the house and too expensive and useful to scrap or sell. Nothing in its handbook about meeting any radio frequency emissions either. Does anyone else have one and if so can they confirm there's is doing the same in terms of RF emissions?
So in the absence of any of you having a better solution, I am going to see if I can find my old tin of Electrodag to paint the inside of it's plastic case of this jump starter. This is a conductive grey coating paint I used to use to coat the inside of the plastic cases on Microbee computers to similarly stop RFI when I was playing around with them in the 1980's. I can't help thinking the "dag" part in the name came from it sheep dag like consistency. I was hoping Altronics, Jaycar RS Components etc would now have any similar stuff in a spray can at a reasonable price. In any event, after 30 years on I expect my can of Electrodag may have gone from daggy to chunky. It's now a Henkel Loctite product and very expensive per:
https://www.laddresearch.com/chemica...graphite-paint
There is this on ebay
https://www.ebay.com.au/itm/Conducti...AAAOSw5ohep~iF and this
https://www.altronics.com.au/p/t3133...aint-jar-50ml/ Not cheap and not in a spray can. I gather musos use similar stuff to paint the inside of their electric guitars e.g.
https://www.ebay.com.au/itm/Professi...cAAOSwNSxU9fyM so perhaps if any of you are electric guitar musos, you might also be able to suggest a source.