[time-nuts] HP10811 dual oven

Pete Lancashire pete at petelancashire.com
Wed Aug 5 14:20:55 EDT 2015

Interesting, mine does not have a HP tag, just a dot-matrix printed label
with one line. Hopefully by next spring I'll be set up to where I can do
some 'real' checking of the the oscillators I have.

Thank you for the enlightenment


On Wed, Aug 5, 2015 at 8:13 AM, Charles Steinmetz <csteinmetz at yandex.com>

> Pete wrote:
> When I got it, my luck won this time, one of the coax
>> cables is tagged 10 MHz and the other EFC.
> That, by itself, does not differentiate between an HP 10811 and the
> Symmetricom OCXO -- they are identical 10MHz oscillators externally (the
> doubler in the Symmetricom is internal).  In my experience, the only
> conclusive external feature is the presence or absence of the Hewlett
> Packard ID on the serial number sticker.  10811s have a serial number
> sticker with Hewlett Packard ID (see photo below).  If the serial number
> sticker doesn't have the HP ID, it is the Symmetricom oscillator.
> As I noted, having the Symmetricom oscillator is not necessarily a bad
> thing -- mine is better than all of my 10811s, including the selected 10811
> that came out of an HP5390A frequency stability analyzer.  (This should NOT
> be read as a claim that the Symmetricom oscillators are better than 10811s
> -- my sample of the Symmetricoms is way too small to justify any conclusion
> in this regard.  But this particular Symmetricom happens to be a very fine
> "10811 class" OCXO.)
> Best regards,
> Charles
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