[time-nuts] hp 5245L counters with 10544 and 10811 OCXOs

Tom Van Baak tvb at LeapSecond.com
Wed Jan 10 03:08:16 EST 2018

And for anyone working on the 10544 oscillator, Charles Steinmetz writes:

> The errors HP made in the 10544 schematics are grave enough that it may 
> be a good idea to post my corrected schematic wherever folks who need to 
> work on the oscillators are likely to look for service information, so 
> they might be spared the confusion that HP's original schematics can 
> cause.
> To this end, please feel free to post the corrected schematic
> on your 10544 page if you want.  I'm also attaching a description of the 
> schematic errors, and a document describing the differences between 
> 10544 and 10811 connections. Feel free to post these on leapsecond.com, 
> as well.

I've place Charles' PDF's at http://leapsecond.com/museum/10544/

Well worth the read. Thanks Charles.


----- Original Message ----- 
From: "Loney Duncan" <loney2 at sbcglobal.net>
To: "Tom Van Baak" <tvb at leapsecond.com>; "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Tuesday, January 09, 2018 5:54 PM
Subject: Re: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs


I'm very grateful for your immediate response, and all that you sent me. 
The last four PDFs are exactly what I need to understand and troubleshoot 
the ailing adapter board.  This is my first experience with Time Nuts, and 
I'm impressed.

Again, many thanks!

-----Original Message----- 
From: Tom Van Baak
Sent: Monday, January 8, 2018 11:19 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs


You'll find the schematic for the 05245-60033 adapter board at the bottom 



----- Original Message ----- 
From: "Loney Duncan" <loney2 at sbcglobal.net>
To: <time-nuts at febo.com>
Sent: Monday, January 08, 2018 8:08 PM
Subject: [time-nuts] hp 5245L counters with 10544 and 10811 OCXOs


I have two 5245L counters which appear to have had a field mod where the 
original 1 MHz cylindrical oven standard has been replaced by the 10544 and 
10811 10 MHz ones.  Both counters have late 4-digit serial prefixes.  Both 
of the standards plug into an interface circuit board that, among other 
things, appears to have a divide by 10 circuit to produce a 1 MHz output to 
the counter’s oscillator card as the old cylindrical oven standard did. 
This card for both has an hp p/n 5245-60033.

My 10811 counter works well, but the 10544 unit has a troublesome 
intermittent problem that appears to be on the board.  I cannot find a 
schematic and parts list for this board to troubleshoot and repair it. 
These probably were on a change insert into the counter Service Manual, but 
I’ve yet to find one.  Have checked on Keysight’s website with no success.

Would anyone in this group possibly have these, or point me to an archive 
that would?  I very much would like to have the 544 unit function.  I have 
observed that after many decades of aging, a lot of the old original oven 
standards are out of adjustment range, while my 544 and 811 OCXOs can still 
be adjusted.

Thanks very much for your advice.

Loney Duncan  W0GZV

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