On 12 Sep 2014 03:35, "Alex Pummer" <[email protected]> wrote: > > No that is to much, except if you overdrive it and you are so lucky that after it broke it is still working on a different frequency, but I would suggest check your frequency counter too, because 3% off of a clock frequency wold make the clock almost unusable not just for time nuts... > 73 > KJ5UHN
This was a follow up post to something I wrote a year ago. I think you have misunderstood me. 1) The clock is in a commercial instrument - HP 8720D vector network analyzer. 2) When I got the instrument the internal clock which gives the date and time was loosing about a day per month, which is roughly 3% from a quick mental calculation. That was an unacceptable 3) Now it keeps within a few seconds per month. I have not bothered checking the actual frequency of the oscillator with a counter or logging the time reported by the clock on a regular basis, but it is now sufficiently accurate for my usage. I only use it to record the date and time I take a measurement with the network analyzer. Given a typical set of measurements takes a minute or so, worrying about the exact time is pointless. There must be at least 3 independent oscillators in this machine. 1) Real time clock. 2) 10 MHz standard oscillator. 3) Optional high stability 10 MHz oscillator. I don't know if that is an oven or not. I know last time it was calibrated by Agilent is was off about 0.25 Hz. When the VNA was calibrated by Agilent a year ago, the accuracy of the RTC was not checked. There is no published specification for it. The standard 10 MHz oscillator was within spec. I don't recall the error. The optional 10 MHz high stability oscillator was in error by about 0.25 Hz. The specification is +/- 1 Hz. I don't know if that is an oven or not. There's nothing to indicate the oven is cold, but given the specifications of the instrument are based on a one hour warmup period, maybe HP thought there was no point in indicating if the oven is cold. Or maybe there's no oven. Dave, G8WRB _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
