Thank you for putting this together Alan, it would have taken me a long time, to get anywhere near, I've got some time off this week so I'll do the build, I've already soldered a 555 & a Lm324n , on the board. I do seem to have a fascination with these generators and how they work, a long with test gear in general. I also found it very interesting the tracking generator, you were using checking the filters on the linear, they look a serious build. and I think expensive I would imagine as is the spectrum analyzer that goes with them, even on E-Bay they command a high price., I compliment you on your excellent and informative videos always a pleasure to watch.
Paul de M0BSW