REF01...

[John Larkin]

Here\'s my REF01 in a box. I set the trimpot a few years ago and just
pulled it out of a drawer and powered it up.

https://www.dropbox.com/s/oxcpiud5dprhkur/REF01.jpg?raw=1

We\'re going to test some oscilloscopes for vertical gain stability.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Larkin]

On Wed, 15 Dec 2021 12:52:42 -0800, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

Here\'s my REF01 in a box. I set the trimpot a few years ago and just
pulled it out of a drawer and powered it up.

https://www.dropbox.com/s/oxcpiud5dprhkur/REF01.jpg?raw=1

We\'re going to test some oscilloscopes for vertical gain stability.

I should also measure their 50 ohm input impedance stability. Somehow.



--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Phil Hobbs]

John Larkin wrote:

Here\'s my REF01 in a box. I set the trimpot a few years ago and just
pulled it out of a drawer and powered it up.

https://www.dropbox.com/s/oxcpiud5dprhkur/REF01.jpg?raw=1

We\'re going to test some oscilloscopes for vertical gain stability.

That must be the A grade. Back in the day they came in grades all the
way up to G, iirc. (The cheapest was always referred to as \"crap
grade\". Amused the sales reps no end.)

The other nice thing about the REF-01 (of which I have probably 10 in my
lab drawer) is that it has a reasonably-accurate PTAT voltage output. I
used to use it to temperature-compensate other things, back in the
pre-MCU days.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Spehro Pefhany]

On Wed, 15 Dec 2021 12:52:42 -0800, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

Here\'s my REF01 in a box. I set the trimpot a few years ago and just
pulled it out of a drawer and powered it up.

https://www.dropbox.com/s/oxcpiud5dprhkur/REF01.jpg?raw=1

Nice.

>We\'re going to test some oscilloscopes for vertical gain stability.

Temperature, time or both?

What\'s your expectation? I guess I\'d not expect much better than
+/-100ppm/degree C, maybe worse.
--
Best regards,
Spehro Pefhany

 

[server]

On Thu, 16 Dec 2021 01:46:11 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Wed, 15 Dec 2021 12:52:42 -0800, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

Here\'s my REF01 in a box. I set the trimpot a few years ago and just
pulled it out of a drawer and powered it up.

https://www.dropbox.com/s/oxcpiud5dprhkur/REF01.jpg?raw=1

Nice.

We\'re going to test some oscilloscopes for vertical gain stability.

Temperature, time or both?

What\'s your expectation? I guess I\'d not expect much better than
+/-100ppm/degree C, maybe worse.

My customer wants about 1000 PPM noise+stability on some fast pulses
driving an e/o modulator, measured over 8 hours. So we need better for
the measurement gear. His temperature spec is +- 0.2 C! We may have to
put the DUT and the oscilloscope in a temp chamber. Nuisance.

We also have a jitter + drift spec of 5 ps RMS for our fairly complex
box, also 8 hours. That may be harder to measure than amplitude. No
oscilloscope that we can afford would have that sort of performance
trigger-to-vertical, but we might get it vertical channel-to-channel,
with some math. Even cables will be a problem.

It\'s an interesting math problem to slurp a list of points from a
sampling scope

time1 vert1 vert2
time2 vert1 vert2

etc, and compute RMS jitter between channels. A sampler can take the
vertical measurements simultaneously, but only one pair per trigger.

Time drift is easy to compute.

Jitter is easier to compute if it\'s a modern digitizing scope, but the
old samplers are a whale cheaper per GHz. Like 2000:1 or something.




--

I yam what I yam - Popeye