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Dave,

Time standards are easier than ever now, as there are a plethora of GPSDO
products around. That will be orders of magnitude better than needed for
aligning cathode ray o-scopes. I adjusted the (admittedly crude) Bulova
branded OCXO in my Type 184 to many more decimal places than needed for
scope calibration. I do leave the 184 plugged in at all times so the oven
stays hot.

For DC voltages, you can find things like this:


With a few things like that on hand, you can easily know that a CRO is in
good shape. Probably not sufficient for more accurate instruments that
require incredibly good calibration accuracy (>=6.5 digit meters, spectrum
analyzers, etc), but will serve you fine for oscilloscopes.

As for professional cal services, I do know Keysight will work on
personally owned stuff (and a lot more old HP stuff than you might think, a
lot of that is still in service in pro labs), but get ready to open your
wallet. Especially if you want NIST traceable.

Sean

Dave,

Time standards are easier than ever now, as there are a plethora of GPSDO
products around. That will be orders of magnitude better than needed for
aligning cathode ray o-scopes. I adjusted the (admittedly crude) Bulova
branded OCXO in my Type 184 to many more decimal places than needed for
scope calibration. I do leave the 184 plugged in at all times so the oven
stays hot.

For DC voltages, you can find things like this:


With a few things like that on hand, you can easily know that a CRO is in
good shape. Probably not sufficient for more accurate instruments that
require incredibly good calibration accuracy (>=6.5 digit meters, spectrum
analyzers, etc), but will serve you fine for oscilloscopes.

As for professional cal services, I do know Keysight will work on
personally owned stuff (and a lot more old HP stuff than you might think, a
lot of that is still in service in pro labs), but get ready to open your
wallet. Especially if you want NIST traceable.

Sean

Dave,

Time standards are easier than ever now, as there are a plethora of
GPSDO products around. That will be orders of magnitude better than
needed for aligning cathode ray o-scopes. I adjusted the (admittedly
crude) Bulova branded OCXO in my Type 184 to many more decimal places
than needed for scope calibration. I do leave the 184 plugged in at
all times so the oven stays hot.

For DC voltages, you can find things like this:

gital-voltage-source-v2-detail

With a few things like that on hand, you can easily know that a CRO is
in good shape. Probably not sufficient for more accurate instruments
that require incredibly good calibration accuracy (>=6.5 digit meters,
spectrum analyzers, etc), but will serve you fine for oscilloscopes.

As for professional cal services, I do know Keysight will work on
personally owned stuff (and a lot more old HP stuff than you might
think, a lot of that is still in service in pro labs), but get ready
to open your wallet. Especially if you want NIST traceable.

Sean

Hmm,

Seems kind of a mixed bag then. I would love to get my own level and time references setup. I have only superficially heard about using GPS based clocks/timing. Seems this might be my opportunity to learn up on that. And thanks for the level reference link Sean. I'll follow up on that too.

The spectral requirements of the SG503/504 sounds out of my league. When opening up my wallet for a place like?Keysight, are we talking 100s? It certainly can't be more than, say, $500 for calibrating one plug-in? Can it? But paying for professional services does get expensive fast.



On Sunday, May 23, 2021, 9:24:27 PM PDT, Eric <ericsp@...> wrote:
For timing a good (lots of digits) frequency counter hooked to a GPSDO will get you where you need to know then you time reference Is based on the GPS clocks which are HIGHLY accurate. At least WAY more accurate then a 400 series scope at 3%. I did a TG501 and a 184 in my lab with a DMM, Frequency counter, and 100 Mhz scope. There is one adjustment in the 184 that you have to balance 2 trigger points these are the 2 bright spots the should be level.? But the SG503 and 504 need spectral purity characterized as well as the SG503 needs that odd 50 Ohm cable. I have to tare in to my 503 it kind of went nuts on me when I was working on a 465. Sorry for the 2 replies I started this on the small screen and moved to the large one.

Eric

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Dave Peterson via groups.io
Sent: Monday, May 24, 2021 12:06 AM
To: [email protected]
Subject: [TekScopes] Getting calibration equipment calibrated

Hi All,

How much does it cost to get PG506s, SG503/SG504s, and TG501s calibrated?

I can certainly search for local calibration facilities, but having no experience at all: do they tend to be amenable to DIYer's, is the cost in the realm of reasonable, is it worth it?

I have a PG506 that's working beautifully, but I can't be certain that the voltage levels are in spec.

The SG503 seems to work, and I can tell pretty well that it's level above 100MHz, but only on an un-calibrated 7854 scope. So while I feel good about the 100MHz scopes I'm testing with it, no one could call that calibrated.

The TG501 is dead, the SG504 blew a fuse when pressed the "ref" button. So those will need some repair. If I can get them working it would be nice to add them to the calibration set.

It'd be really nice to have all four of these officially calibrated. That'd give me assurance that the scopes I'm repairing are properly tuned up. I don't have any means at hand otherwise to verify level or timing. I could keep working on finding means of establishing standards for level and time. But would it just be more cost effective to pay for calibration?



Thanks,
Dave

On May 24, 2021, at 07:58, walter shawlee <walter2@...> wrote:

?Outside calibration is complex situation, especially since it is understood differently by the
providers of the service, and their customers. this disconnect can be severe, and often leads to
some significant unhappiness on the part of equipment owners.

I documents all olf this in detail when I was writing for the AEA (Aircraft Electronics Association),
you can grab those articles HERE on our site:


look halfway down the left hand yellow area where you see the AEA logo. "understanding calibration"
be aware that you will likely get your gear back just as you sent it, with no improvement at all.

I love metrology, and the whole idea of chasing precision to wind up with things as accurate as possible.
I have a GPS, three rubidium standards, and three high end OCXOs I cross check just to get a clean
known 10.000000Mhz value for doing counter calibration. This path is NOT for everyone, and no single standard,
without regular external validation is of any value in the calibration world. Every lab should have some known
references as a sanity check, even if it's just a few precision resistors and known frequency. Known DC voltage
can be harder, and known AC voltage harder still.

One of my best friends runs a metrology lab here, and I watch what he has to go through each year to
have traceable accredited standards, it is not for the faint of heart. I am eternally grateful he helps me
with my cals, or I could never really be sure of anything.

all the best,
walter

--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:-
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)

On May 24, 2021, at 12:22, Jeff Dutky <jeff.dutky@...> wrote:

?Dave,

for a voltage reference you can get something quite economically (less than $25) on Amazon or eBay that is based off an AD584:





This should let you get a good bead on your meters. Of course, if you have more than a couple meters you can just take the average of their readings and call it good enough for government work (or for DIY calibration).

They say that the man with several multimeters never knows the correct value of a measurement, but you can just average them all together and get a pretty good bracket. Also, if you are measuring a "known value" (e.g. the voltage on a new battery) you can get a good idea of 1) how close your meters are to true, 2) the variance is across your meters, and 3) which meters read low or high and by how much.

Frequency standards can be had almost as cheaply:



everything I saw on eBay was more expensive, but also looked like it was higher quality:



or you can buy a brand new GPSDO from Leo Bodnar for $140 + s&h:



but I know that you already have a tinySA, which will probably serve as a frequency reference too (maybe also as a voltage reference?). Throw in a couple of random TCXOs, average across several different frequency counters, and again, you're good enough for government work.

-- Jeff Dutky

On May 24, 2021, at 12:22, Jeff Dutky <jeff.dutky@...> wrote:

?Dave,

for a voltage reference you can get something quite economically (less than $25) on Amazon or eBay that is based off? an AD584:





This should let you get a good bead on your meters. Of course, if you have more than a couple meters you can just take the average of their readings and call it good enough for government work (or for DIY calibration).

They say that the man with several multimeters never knows the correct value of a measurement, but you can just average them all together and get a pretty good bracket. Also, if you are measuring a "known value" (e.g. the voltage on a new battery) you can get a good idea of 1) how close your meters are to true, 2) the variance is across your meters, and 3) which meters read low or high and by how much.

Frequency standards can be had almost as cheaply:



everything I saw on eBay was more expensive, but also looked like it was higher quality:



or you can buy a brand new GPSDO from Leo Bodnar for $140 + s&h:



but I know that you already have a tinySA, which will probably serve as a frequency reference too (maybe also as a voltage reference?). Throw in a couple of random TCXOs, average across several different frequency counters, and again, you're good enough for government work.

-- Jeff Dutky

Crab Apples can actually make some damn good apple pie. As with cherry
pie, you really want something very sour for the filling: gives it better
flavor.

-- Jeff Dutky (who grew up on 2 acres with 5 apple trees, 3 sour cherry
trees, and all the pie you could eat)

On May 24, 2021, at 14:19, Ken Eckert <eckertkp@...> wrote:

?A really handy bench reference is the Fluke 515A, does DC, AC, and Ohms. No
current though.

On Monday, May 24, 2021, Jeff Dutky <jeff.dutky@...> wrote:

Crab Apples can actually make some damn good apple pie. As with cherry
pie, you really want something very sour for the filling: gives it better
flavor.

-- Jeff Dutky (who grew up on 2 acres with 5 apple trees, 3 sour cherry
trees, and all the pie you could eat)

On May 24, 2021, at 14:34, walter shawlee <walter2@...> wrote:

?I agree, a fluke 515A is an excellent calibrator (if working and calibrated) for any home lab, maybe ditch the batteries, they are nothing but trouble. They show up regularly, but again, the issue is how do you know it's still good, especially if you buy it used? Being defective is the usual reason they get sold. Others have mentioned some very good DC references that can be used to cross-check it that are not expensive, so you can get to the goal line if you are careful. Also, make friends with somebody close by that has a better bit of gear than you do so you can do a quick check or cal if needed. Outside validation is essential.

I use a regularly cal'd Fluke 5100B to do my DMMs and similar items (I had several 515As, but got rid of them for this), plus I cross-check to a cal'd hp 34401A (I just can't afford a 3458A, but it is the magic weapon if you can afford to cal it!). I also built a super stable 10.0000VDC reference I use as a secondary cross-check, along with a selected super stable 10k resistor.

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.