Brian. I have quite a lot of EMERs on the No.4 Mk 7 but I don't know how it differs from Mk 6.
I am glad there are at least over there some early centimetric enthusiasts. I started fiddling around with X-band kylstrons in 1972. I also worked on (in the amateur sense) 70cm, 23cm, 13cm, 9cm, 5cm, 1.5cm, 1.2cm. Eventually I was running CW/SSB on 10Ghz. My main interest was tropo scatter.
But there was some interest from others on low power devices, kylstrons then Gunns going to sea level & doing super-refraction. It is amazing to see the wartime research on bands down to X across the Irish Sea from the Isle of Man. One can well see how the radar installed on a small boat or submarine had a greater over the horizon range than a battleship!
I dropped out of amateur radio about 20 years ago. I was using homebuilt gear with much waveguide feeding TWTs. However things have “moved on” apparently. Virtually no gear is home built now, most people are using professionally built solid state gear producing several watts on 10Ghz. These rigs cost several thousand pounds & when they pack up, they are sent back to Germany for repair.
I have accumulated a lot of WG16 & WG14 with components including kylstrons, power meters, slotted lines, wavemeters etc. But nobody seems interested in anything like that any more! Sickening when I had paid so much for stuff that I dismantled from radar systems in scrapyards! Eventually I'll sell it for scrap, but that somehow seems immoral!