In reply to G6TUH:
A few years ago I had terrible QRM across most of the HF spectrum but peaking around 5MHz. As Brian mentioned I used my 817 with it’s 6M helical aerial and tracked it down to a neighbour’s kid’s fridge which he keep in his room. It appeared the noise was being induced back into the mains wiring which was acting as a pretty good radiator.
Having pointed this out to the neighbour I said that they didn’t have to do anything as I would come up with the solution. I ordered a couple of mains filters from RS and fitted them into single 13A MK Type holders (about 50mm depth)with extension lead (1M)and plug. I gave one to the neighbour to fit between the wall socket and the fridge. Problem solved.
A few months later the neighbour gave me the the lead back, stating that it was no longer required as like Walt’s problem - the fridge had given-up-the-ghost!
Todate I haven’t had to use either of the leads, but there there just in case?
Now how to get rid of data noise - pops, purrs, squeaks, wow-wows, meows etc! Oops now where did I leave the cat?
PS: The 817 is also great for tracking down car bourne noise and where it is eminating from. Now solving it in modern cars - that’s another problem - hi!