); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] Magnus Danielson wrote: > Hi fellow time-nuts, > > As I was going to make a casual measurement of the HP 5370B 10 MHz output, > i.e. > that of its HP 10811-60111 OCXO, I came to see an unexpected modulation. It > has > a slow modulation frequency modulation of about 5,2 mHz or there abouts. Quite > digital/squarewave-like I might add. Not actually squarewave, but rather some > form of PWM signal. Another interesting aspect was that it had a fairly steady > high, abrupt fall down a slight recovery, a jump upwards and then fall up to > the steady high level. The high frequency was the longer part of the time. > > The cycle-time of these are low, for the 200 5 sec samples I took, I had about > 10 cycles or so. So it is about two minutes cycles. The rate varied greatly. > > I have not seen any specific details in the HP 5370B service manual about > where > the HP 10811-60111 EFC is hooked up to anything, but I have noticed that more > or less everything is grounded on the connector. Now, if there is > low-frequency > modulations of any large current there, it may kreep in. But it seems a bit > high for that. > > I used both a Pendelum CNT-90 as well as a HP 5372A to measure this. I used > both the Cs and Rb as reference and it made no difference. The CNT-90 between > the two showed only noise, so this quick and dirty three-cornered hat > certainly > pointed its crookied finger at the HP 5370B. The HP 5372A was using its own > well heated 10811-60111 as reference but that told the same story. > > I might add that the 5370B was running in "cabed" condition, i.e. top and > bottom lids where off as well as the right side. The top lid needs to be off > if > you want to have a chance of trimming it. The 5370B has been in bypass 9 days, > so I consider the 10811 fairly heated. > > Has anyone else seen this? Tom? > > Cheers, > Magnus >
Hej Magnus Oscillation/cycling of oven temperature? Oven controller oscillation? Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.