[time-nuts] 10811 warmup
Mark Amos
mark.amos at toast.net
Sat Jan 20 10:15:42 EST 2007
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
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