That CRM533 is a pretty nice looking bit of kit. Never seen that one before.
It is pretty nice, but I guess not many will have survived due to the use of NITs (abbrevation from the Philips_DigitalInstrumentCourse_Part2.pdf I found during the week, I bought something featured in it earlier in the week).
Another Cossor signal generator from that old advert that I didn't see when searching a few weeks back, seems a lot of £££ for something with only two pictures.
https://www.ebay.co.uk/itm/284273960683
David
This is very application specfic AUDIO generator. No RF output. They are used with a VHF signal generator with accurate wideband AM modulation performance. It has two functions Instrument Landing Systems (ILS) and VHF Omnidirectional Range (VOR). These are aicraft VHF navigation systems.
ILS is just 90Hz and 150Hz with accurate differential levels.
VOR is a 9960Hz signal FM modulated with 30Hz and a separate 30Hz with accurately adjustable phase to the 30Hz mondulating the 9960Hz . The older versions used a mechanical tone wheel with magnetic or optical pick-ups. The 30Hz pick-up was physically roatated around the wheel to change the phase.
Showing my age here
EDIT: It also does 400Hz, 1300Hz and 3000Hz spot frequencies for the 75MHz marker system
EDIT: They are built in HP System Cases (System I since System II came out)