On Fri, Jan 29, 2021 at 09:39 AM, unclebanjoman wrote:
The second problem arose during the calibration of the Good SIgnal Flip-FLopThis is an interesting observation, and one that I was able to reproduce with my
7854 using 7B85 and 7B92A time bases. HORZ MODE A is the key -- it doesn't
matter which time base is installed in which slot.
Observing TP122 with 7A13 (using a different mainframe, of course) in voltage
comparison mode allowed me to see what is happening. Namely, with Horizontal
Mode set to A, there are occasional spurious pulses (about 20ns wide) that
show up out of sequence. They get converted to TTL levels along with the real
pulses, and so they throw off the display and make it look like it is "slipping".
As far as I can tell, U105 is just doing its job here and converting these spurious
pulses along with the rest, since they have the same amplitude. Hence, I don't
think this "slipping" indicates an incorrectly set GSF level. I think as long as you
can observe all the real pulses at TP106, with A and B INTENSITY varied
throughout their range, then the GSF level is OK.