[time-nuts] 10811 warmup

[Mark Amos]

Didier,

My experience with 4 10811's with widely separated serial numbers is consistent with your 
numbers below. Between 6 and 8 minutes of warm up from ambient (18C) and they're stable at the 
target frequency as measured with a recently calibrated 5328A (one without a 10811 - since 
remediated!)

The recent bad unit I bought on ebay behaved similarly - it warmed up and within 10 minutes it 
had stabilized around 9,999,915. 

It is adjustable between about 9,999,900 and 9,999,920 or so using the adjustment capacitor 
through the hole in the case.  EFC seems to function correctly as well with a little over 1Hz 
of adjustability with +-5 V.

As has been suggested, it must be some kind of test unit (or perhaps one that failed QA?)

I replaced it with one from AST Global - they had a great return policy, shipped fast and 
packed well.  

In any case, I've retired the bad one as a marker generator at 9.9999 MHz.

Mark

Message: 1
Date: Fri, 19 Jan 2007 22:53:28 -0600
From: Didier Juges <didier at cox.net>
Subject: Re: [time-nuts] Bad batch of HP10811's
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID: <45B1A048.9090207 at cox.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Warmup data on the HP 10811:

Here is some data collected on the internal HP 10811 timebase in my HP 
5370A counter, which had been turned off and plugged off for about 3 days.

21:39:25,  9999798.6
21:39:35,  9999806.0
21:39:46,  9999822.6
21:39:55,  9999836.8
21:40:06,  9999853.2
21:40:15,  9999866.8
21:40:26,  9999881.7
21:40:35,  9999892.4
21:40:46,  9999904.1
21:40:56,  9999913.1
21:40:58,  9999915.2
21:41:07,  9999923.0
21:41:16,  9999930.1
21:41:25,  9999936.5
21:41:36,  9999944.0
21:41:46,  9999949.3
21:41:55,  9999954.3
21:42:06,  9999959.9
21:42:15,  9999964.0
21:42:26,  9999968.6
21:42:35,  9999971.8
21:42:45,  9999975.2
21:42:54,  9999977.9
21:43:05,  9999981.0
21:43:17,  9999983.9
21:43:26,  9999985.9
21:43:35,  9999987.8
21:43:46,  9999990.0
21:43:55,  9999991.3
21:44:07,  9999992.9
21:44:16,  9999994.0
21:44:25,  9999994.9
21:44:36,  9999996.1
21:44:45,  9999996.9
21:44:56,  9999997.7
21:45:06,  9999998.3
21:45:15,  9999998.9
21:45:17,  9999999.0
21:45:19,  9999999.1
21:45:21,  9999999.2
21:45:24,  9999999.3
21:45:26,  9999999.4
21:45:36,  9999999.7
21:45:45,  9999999.8
21:45:56,  9999999.9
21:46:05,  9999999.9
21:46:08,  9999999.9
21:46:10,  10000000.0

After that, the display was a stable 10,000,000.0 for the next 15 
minutes (one reading was 10,000,000.1), then I stopped the data collection.

The counter used was the HP 5334B with the Thunderbolt as external 
reference.

Ambient temperature: about 22 degrees C (cool)

Bottom line: about 200 Hz from a cold start and about 7 minutes to 
within 0.1 Hz of final frequency.

Didier KO4BB