[time-nuts] OCXO PLL gains?

[Rice, Hugh (IPH Writing Systems)]

> The 5061 had an analog double integrator using a $100 op amp.
> Maybe Hugh Rice can speak about that. You have to have the 2nd
> integrator to prevent a ramping error term from turning into a
> frequency offset instead of getting integrated out.

I never studied the control loop design on the 5061A/B.  It worked just fine, so I didn’t dig into it.
I’ll mention the $100 op-amp more in another story in the future, but it wasn’t nearly as exotic as it looks.
I recall it being a hybrid circuit monstrosity – a whole bunch of discrete components all potted in blue plastic, and about 2” x 2” in size.
My guess is that it was a high performance device, during the transition days from making op-amp with discrete parts on PCAs
(like the 5060A did in the 1960s), to fully integrated op-amps in the 1980s.   An awkward teen-ager of electronics from the early 1970s, so to speak.

Modern IC op-amps probably could replace it just fine.   Our super-technician/engineer on the production engineering team, Dave Montgomery,
used to say we should replace it with and “Op-07”, his favorite high-end op-amp.   It costs $.45 each now, if you buy 1000.

Hugh



From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Richard (Rick) Karlquist
Sent: Sunday, February 3, 2019 8:41 AM
To: Magnus Danielson <magnus at rubidium.se>; Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Subject: Re: [time-nuts] OCXO PLL gains?



On 2/2/2019 3:06 PM, Magnus Danielson wrote:

>>   We also used a double integrator
>> on the 5071A cesium standard, but cesium loops are NOT PLL's.
>
> Indeed, double-integrator in FLL is a separate class of problems.
>
> Didn't know it had double-integrator.
>
> Cheers,
> Magnus

The 5061 had an analog double integrator using a $100 op amp.
Maybe Hugh Rice can speak about that. You have to have the 2nd
integrator to prevent a ramping error term from turning into a
frequency offset instead of getting integrated out.

Rick

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