I have a 8568B spectrum analyzer which has some strange flickering traces sometimes. I found out that the traces do not flicker if the frequency span is narrow, for instance 1 MHz. As soon as I use a wider span, the traces are kind of unstable.

I then opened the RF section and found following behaviour: with a large span, the YTO unlocked LED flashes sometimes, however, I get no YTO warning on the screen.

If I lower the span to 1 MHz or less, the YTO unlocked LED is off all the time and the traces on the screen are nice and stable.

Is it normal that, when larger spans are used, the YTO unlocks from time to time? If not, why don't I get the YTO unlock message on the screen?

Tobias, HB9FSX