Hello Tobias,
Monday, November 19, 2018
I had something remarkably similar (I can link to a video if you
wish) and after i gave up home diagnosis a professional UK firm found
the YIG faulty. They replaced it at some cost and it's been perfect
since then.
Best regards,
Chris mailto:chris@...
TP> While I was working on my power sensor thing, I wanted to check
TP> the spectrum of some signal generator by using my 8568B spectrum analyzer.
TP> About one year ago, I had the problem that the analyzer had some
TP> intermittent noise, i.e. it was mostly working fine, but for short
TP> periods, its noise rose quite a bit. I was not able to determine
TP> the source of the problem, but after a while, it somehow fixed
TP> itself and didn't appear anymore.
TP> UNTIL NOW! ARGH! I need to fix this.
TP> I made a video (it is quite loud, so lower the volume a bit! :-)):
TP>
TP> The signal shown on that screen is an ultra low phase noise OCXO
TP> which is powered up since a week or so, so it has definitely
TP> settled in frequency. One can clearly see that most of the time,
TP> the signal is displayed nicely, but for a short time, the noise
TP> rises quite a bit and there are some artifacts visible.
TP> I have already checked the power supplies, and they seem to be
TP> fine and within spec. The spectrum analyzer is also powered since
TP> about two weeks or so, so its internal OCXO is definitely also settled.
TP> What else could cause this type of problem? has anyone ever seen
TP> something like that? I was also thinking whether it is some sort
TP> of ground loop or so, so I removed my OCXO signal and connected
TP> the calibrator signal. Same behaviour, so I assume it's something generated within the analyzer.
TP> Any ideas?
TP> Best
TP> Tobias HB9FSX
