开云体育Hi,I have the manual, of course :-)
But I cannot find some info about when the YTO is allowed to be unlocked.
I also have not yet managed to fix the flickering trace. Actually, 'flickering' ist not quite the right expression; it is a bit more complicated: if there is a signal on the screen and the marker is moved along the trace, the trace is slightly 'pulled'
along the frequency axis towards the direction in which the marker is moved, which looks like an unstable, flickering display if the marker is moved fast (e.g. when turning the knob rapidly). As soon as marker movement is stopped, the trace bumps back at its
former position.
However, this absolutely strange behaviour can only be observed when the span is wider than 1 MHz; in this case also the YTO unlock LED is flashing (but no warning message on the screen).
I hope I have some time tomorrow to check the tant caps. I hope it is not the YTO or a mixer which went on the blink, but I guess as long as the YTO oscillates and signals can be viewed correctly (in principle) on the screen, then the RF path seems to
be all good.
Tobias
-------- Original message --------
From: "edbreya@... [hp_agilent_equipment]"
Date: 10/15/17 20:34 (GMT+01:00)
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: 8568B YTO unlocked
?
I don't know about the screen flickering, but I do think the YTO loop behavior is normal. At wider spans it is not constantly phase-locked - it is driven open-loop with fairly accurate sweep current, and I think possibly re-phase-locked just at the beginning
of the sweep each time around. For wide spans, you can't resolve the small frequency error on-screen anyway, but for narrow ones, more stability is needed, so the LO is locked. It's also possible that the narrow spans instead fix the first LO and use the second
LO for sweeping - I can't recall for sure, but it should be one of those two schemes. |
