Chuck wrote:
Small tweeks to the fine freq ... adjustment take several minutes to take effect. Is the fine adjustment tweeking some parameter related to the oven???
I doubt it, but I do not have actual knowledge of the inner workings. I have found that the heat loss (I assume) through the open adjustment plug screw causes an error -- you can get them adjusted as closely as you can (in my experience, about 1E-9 with lots of hair-pulling) and they will sit there stably for as long as you want, then when you put the plug screw back in they drift several parts in e-9 or more over a period of 10-15 minutes and stabilize at a new value.
The good news is that the Racal oscillators in my 1992s are very stable long-term performers -- and significantly less position-sensitive than many others. So, you don't have to adjust them very often. The bad news is that getting them really, really close to the desired frequency is like herding cats. Other than the flaky pushbuttons on some of them, I have found that 1992s are extremely dependable. When a 9-digit counter will do, they are a great choice. (Of course, as time/frequency nuts we quickly outgrow 9-digit counters. Doesn't every measurement require 12 digits referenced to an H-maser?)
I think it's been asked, and recently, but I haven't seen a positive response. Does anybody have schematics for the Racal OCXOs they can make available?
Best regards, Charles _______________________________________________ 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.
