[time-nuts] HP 10811 stabilizing time

[Magnus Danielson]

Hi Rick,

Curiously enough, 5335A is the only counter that I know of that produce
Slew-rate measures, which is trival to calculate from the rise-time (or
fall-time) and the voltage difference between the start and stop
triggers, but yet nobody seems to care for that measurement. At the same
time, what is given in the manuals for trigger jitter? Slew-rate. 5335A
remains my favorite bench counter even if I have other counters that has
better performance.

Cheers,
Magnus

On 2019-07-22 05:10, Richard (Rick) Karlquist wrote:
> Hi Perry, I worked in the HP frequency counter section in the 1980's
> when the 5335A was developed.  I was the project manager for the
> 5334B counter.  Basically, no counter that we ever made AFAIK had
> any provision for EFC.  The basic concept is that you can get the
> frequency close enough with the coarse adjust, say 1 part in 10^8.
> Unfortunately, your email was garbled and we only know you were
> able to adjust it to 4 to 6 parts in 10^????.  Attempting to
> put in EFC would entail getting some very temperature stable
> and low noise reference and some very low TC multiturn pot.
> Lots of things to go wrong there.  If there was enough demand
> for that feature, it is likely that HP would offered it as a
> extra cost option.
>
> If you want to add EFC yourself, it is on pin 6 of the edge
> connector.  You might have to liberate that pin from ground.
> The coarse adjustment is a high quality piston trimmer; no
> way to do any better there.
>
> HP was certainly not infallible, but I think you are giving
> them a bum rap here.  There were many highly talented engineers
> in that section (I knew them all).  The project manager of
> the 5335A was eventually promoted to R&D manager and he was
> the boss of the counter section manager.
>
> Rick Karlquist
> HP Santa Clara Division 1979 to 1998.
>
> On 7/21/2019 6:53 PM, Perry Sandeen via time-nuts wrote:
>> Yo Bubba Dudes!,
>> I bought a HP 10811 from ebay for $36 and shipping.
>> I installed it in my HP 5335a counter.  After running continuously
>> for about 90 days it was down to about 4 to 6  parts in -10.  I
>> couldn't adjust it for better accuracy as HP in their infinite and
>> inscrutable wisdom provided a edge connector for the 10811 but didn't
>> make provision for EFC one had only the course adjustment.  Sheesh!
>> Now maybe I was very lucky in my ebay purchase.  On ebay prices seem
>> to go from $125 to around $60.  One of the lower priced sellers
>> advertise that their 10811's are *tested* but no details.
>> Regards,
>> Perrier
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