I found a defective HP8566b spectrum analyzer for sale.
It was working but showed unlock an the screen and it was not showing any positive response on frequencies at input.
Special on this instrument for me personal was that I had been working with this particular instrument in 1981 when I was on internship at the Technical University in Eindhoven. During a period of half a year I worked almost daily with this instrument and I was very fond off it. So I could not let this opportunity go by and had to buy it and see if I could repair it.
I searched for quite some time before I was sure what the
After a long search I tried to measure the YIG itself to see
if it was working and found it had no output power at all.
After arrival I mounted the replacement YIG into the analyzer and powered the analyzer up.
The YIG oscillator proved to be the problem, the analyzer was working fine
I was very happy with this for me special instrument.
A few years later I decided to open up the defective YIG and take a look inside.
Opening the YIG was not very easy but by cutting the exterior shielding I succeeded in getting to the YIG.
The YIG itself can be opened quite easily so there is almost no risk for damaging the YIG oscillator itself.
This is a picture of the YIG
When zooming more closely I found the problem.