This was in Elektor in 1980. Its based around an XR2206 which was a defacto signal generator IC.  https://www.elektormagazine.com/magazine/elektor-198001/44362. There are also some early Vocoder designs around that time which would be very authentic.    

Hello Glenn. Thanks kindly for supplying the 2 oscilloscope probes and the 2 other oscilloscope leads.   Previously found the online datasheet for the oscilloscope and printed off a copy.   Back to SSR model B. Maybe Kev is a bit too hard on my own design. 1st day I plugged it in and it was noisy when compared to the more advanced SSR model A. 2nd day and it was less noisy. Been going around and checking the different voltage levels. Less that 50% volume and slower LFO speed and it is okay, with some bleed through noise. Bigger volume level and full LFO speed is where it gets really noisy.   So an adjustable low pass filter is the next idea. See if I can located which frequency range of sound is making the high frequency noise.   The SSR model A just has that magically performance. The SSR model B is where I took a lot of short cuts to make it easier and cheaper to build.    

I used the outside of a wok to make my dish. PVA release and a couple of layers of fiberglass and it was done.

Gambling £6 on this - if it looks okay will save me £50 on the proper replica radar dish...!