[time-nuts] HP 5370A

David McGaw david at endor.com
Sun Oct 15 01:34:06 EDT 2006

The 10811 is the newer SC cut crystal oscillator.  The 10544 would be 
the older AT cut oscillator.

At 09:43 PM 10/14/2006, you wrote:
>I got an HP 5370A from eBay which did not work at power up (display was
>messed up). After resetting all the ROMs and the CPU in their sockets,
>the instrument came to life and now powers up without error message. It
>has serial number 2128A01306.
>However, it seems that the reference oscillator output is severely
>distorted (when I look at it with the scope), it looks more like 900mV
>p-p of 30 MHz than 10 MHz, even though the instrument does not complain.
>The output looks the same if I drive the external reference or use the
>internal reference. When I measure the reference output with the 5370
>itself, I can make it display 10 MHz, 20 MHz or 30 MHz just by adjusting
>the threshold pot.
>I have posted a picture at http://www.ko4bb.com/Test_Equipment/HP
>Also, I went through the instrument check out, and the first step, page
>3.4, shows how to read the period of the reference oscillator, and the
>instrument displays 0.00 instead of 100.00. It obviously does not like
>the reference output signal.
>The time base is an 10811-60111, I believe this is the "standard" time
>base, as the manual lists the "high Stability" time base as a
>10544-60011. The 10811 is a pretty nice "standard" time base :-)
>Otherwise, the time base seems very close, my reference oscillator (a
>3586 synchronized to WWV until my GPS clock is finished) displays 10.000
>000 100 on the 5370.
>So it seems some of it is working, but the reference oscillator output
>bothers me, and so does the impossibility to run the check out..
>Any help in figuring out if this is normal would be appreciated.
>Thanks in advance.
>Didier KO4BB
>time-nuts mailing list
>time-nuts at febo.com

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