); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] From: Dr Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] HP 5370B low frequency modulation Date: Mon, 23 Jul 2007 11:14:25 +1200 Message-ID: <[EMAIL PROTECTED]>
> Hej Magnus Hej Bruce, > Oscillation/cycling of oven temperature? > Oven controller oscillation? Might be, but then my "loadingcondition" has caused the oven control out of stability. This would certainly supprice me. The oven control in the 10811 is linear and for most practical purposes behave like a first-degree linear diffrential system. OK, there might be a second degree aspect, but the poles should be fairly stable and it would be more a pure "amplitude" problem. Now as I was down putting the hood on (and removing some of the residues from the not so very smart packaging, using isopropanol) the down-spikes had started to become fewer and rare, and it had 490 uHz of Allan Deviation, i.e. 4,9E-11 for tau = 5 s. I beleive it will considerably lower as the spiking stops. The full 10811 seems powered during standby mode. Some solutions will only have the oven powered in standby. What does change on powerup of the rest of the counter is that you turn on alot more heat, current, the fan (which has a fat metall wall between the flow and the 10811, but that piece of metal wrapps the 10811 so the cool-of-effect may be there never the less. After putting the lid on and letting it sit there the spikes is still evident and last reading gives 5,8E-11 @ tau = 5s. A comperative measure with another 10811 (which I just *happend* to have a cable for lying around on the table) but which was unheated also gave time for a little experiment, looking at the heat-up performance. Now, it started some 200 Hz hot, but went for a steady linear dive downwards which at about 400 s curved upwards and had a gentle overshot (i.e. lower frequency) until it stablized. However, subsequent measure showed a slow but steady rise and ADEV measures was surely limited by the driftrate. It was however much lower, such as 1.2E-11, and that includes the drift-rate tainting while the display indicated a much smoother curve. As I don't have a wiring aisle for my lab-bench (beleive me, I start to consider it as a must have even if it would be a squeeze-in variant of 3-4 dm or so, I could not get the heated 10811 in my 5372A. I really need to hook the backside panels up to a BNC patch any decade now. Anyway, otherwise I would have a well heated alternative to measure on. I wish I get a phonecall with good news from a fellow time-nut tomorrow. If so I drive down to him. :-) Cheers, Magnus _______________________________________________ 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.
