HP 8595E Spec Ann - unusual lockup when FREQ UNCAL error arises

[Tracker]

Hi guys
I am looking for some direction with this fault please.

The 8595E spectrum analyzer (normally 9khz to 6.5 GHz) appears  to work well in low band up as far as 2.7 GHz, but beyond that frequency the FREQ UNCAL error pops up.
according to the manual 'FREQ UNCAL' indicates a YTO issue...
But the unusual bit is that the whole machine locks up and will not respond to any button press except 'PRESET' which resorts default settings.

I tried to run the YTO cal routine which takes about 5 minutes, but when complete it appears to mess up the low band also by adding +300 MHz offset to Low band and it still goes FREQ UNCAL on Band 1

I also ran the Service Diagnostic checks and can see a small but noticeable step in the signal traces.
Photos to follow.

Any suggestions? I am hopeful the YTO is ok and there might be a Logic issue here because of the lock-up.

Thanks

[m k]

I don't know anything about the device and seen the clip only once, but anyway.
Based on your description I guess it can be just a wrong cal source.
If device is seeing its own errors it really can't do much more than revert to default.

Is it ANA_TEST where internal cal input is finally available?
TP2 is shaded but there's also SWEEP+TUNE.
If cal input is there and the problem is those DACs you should see something unusual there also.

Is TP3 of mux U15A something where you can stuff your own cal check signal?

[Tracker]

ok so after some research and some more testing I can confirm its a bad Yig.

I removed the YIG and ran it externally with three PSU's, two for voltage and one for a current limited source to control the main coil (didn't bother with the FM coil) .
This proved to me that the YIG has two problems, it wont cover the required operational frequency span (it has gaps) and then it shuts down after 5 minutes of operation from cold.
So a new YIG is needed.

This seems to be the most common fail on these SA's, 2nd hand Yig's can be got from the far east but you takes your chances there!!!
A company is CA can provide recondition units with a guarantee, provided you donate the faulty Yig.
But it's a tough call to know if the Analyzer is worth the 1000 Euros (approx)  it would cost for a Yig.