[time-nuts] HP Z3801 RB fun

Charles Steinmetz csteinmetz at yandex.com
Fri Dec 30 11:32:32 EST 2016

paul wrote:

> The 10811 is far more difficult to pin down as several articles from TVB
> and others say the 10811 actually has a wider control range then the
> standard. Something like 10 Hz over 10V. Traditional is 1 Hz over 10 V. But
> as I say seems to be different answers depending on what you read.

HP made lots of different sub-models of the 10811.  According to the 
specs, they all had EFC sensitivities of either "at least" +/- 1Hz or 
"at least" +/- 2.5Hz for the -5v to +5v EFC range.  The most 
commonly-encountered sub-models are specified as "at least" +/- 1Hz.

However, the HP spec for the EFC range of the 10811-60158, which was 
used in the Z3801, is (quoting directly here) "> ± 2.0x10-7 (± 2.5 Hz) 
for control range of -5V to +5V".  (Note that 2e-7 of 10MHz is 2Hz, not 
2.5Hz, so there is some internal inconsistency in the spec.)

So, the spec says to expect "at least" 4 or 5Hz (total, or +/- 2 to 
2.5Hz) for the 10v control range (or, "at least" 0.4 to 0.5 Hz/V).  I 
don't believe I've measured one that went 10Hz (total, or +/- 5Hz), but 
I have not taken careful measurements of the EFC tuning rates of many 
10811-60158s.  I certainly wouldn't be shocked to find examples with 
10Hz EFC ranges (1Hz/V), based on the published spec.

Best regards,


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