Test Equipment Anonymous (TEA) group therapy thread

[beanflying]

Brown Santa dropped off some new toys today:



-Pat

Lucky for me that seller wouldn't ship to Oz  There has been a few oddball value job lots recently on evilbay.

One of them is weeping oil, so it looks like there will be some teardown pictures at some point.



(The left hand arm is slightly loose where it emerges from the to cap; I'm hoping that it's something that can be easily tightened once the retaining collar has been unscrewed.  Some quick google searching hasn't gotten me any images or exploded views to let me know the internal construction of this kind of standard, so my fingers are crossed that I don't bugger it up.)

-Pat

They are filled with oil and the tops unscrew. We had a chat a while back about it and Equine sourced Mineral Oil seems to be the answer. (Kosmic's idea I think?) They run fine without but it will dampen the thermal rise in use. If you have a 'spare' 1k let me know and we can arrange a subsidy on the lot if you are interested 

[mansaxel]

Brown Santa dropped off some new toys today:



-Pat

Lucky for me that seller wouldn't ship to Oz  There has been a few oddball value job lots recently on evilbay.

One of them is weeping oil, so it looks like there will be some teardown pictures at some point.

I'm so envious of the opportunity to have these problems! 

My own standards collection is dry, but prepared for immersion. A couple of mine are rattling but not -- as far as I can tell -- affecting accuracy. I'm sort of preparing to break the seals to open them up and see if I can fix the rattling. 

TE footnote: My 3438 is only operative on DC Volts without poking.    If I provoke (hold firmly depressed) the mode selection buttons I can get it to read sensibly in other modes.  Perhaps it's only a simple fault, perhaps it is more. Manual talks about a bit pattern for mode selection.  Will have to open up and poke more internally at that.

[beanflying]

Whats on the inside  The barrel is just the container with thread at the top. The outer Aluminum Cap is removable with a spring clip holding it onto the Bakelite type top.

[Robert763]

Of course if you put a big enough engine on it, you can make bricks and lawnmowers fly.

And pigs, of course.

They put a A400M engine on a C130......
That is one big chock. The TP400M is more than twice the power of the original T56. The airfrrame is the Met Office Research Flight "Snoopy" so already had a bunch of modfications.

[tautech]

Cerebus won the Keysight scope ! 

"ONCE and ONCE ONLY" What? That's what you said to post! 

WINNER WINNER CHICKEN DINNER!

[Bad_Driver]

Hi Ceberus,

during the last year I also played with different OCXO solutions for GPSDOs. I learned that it's better not to cover the OCXOs with foam because the heating-cooling-regulation needs the convection with free air.
It only makes sense to avoid direct air flow from a vent. All the professional solutions I have seen use the "naked" OCXO.

I have done this only one time since I had a OCXO without Vref output and I used a cheap TL431 for this. I put it at the can of the OCXO and covered it with foam.

I don't know why you'd think that. If the control loop for regulating the temperature of the OCXO was so badly designed that it needed some external cooling to be stable your point would be well made, and the control loop would not be. As it is I've never seen this and wouldn't expect to. If it needed a specific amount of convective cooling the data sheet would have to specify the amount of heat dissipation necessary and again, that is not something that I've ever seen. So I think you're a bit off with the expectation that "the heating-cooling-regulation needs the convection with free air".

In general most ovened things, be they XOs or voltage references benefit from having as much isolation from the local thermal environment as possible. Some ovened references go so far as to place the oven inside a dewar flask ('vacuum' flask). That you don't see it in many commercial designs is probably more likely down to being cheap than being about doing the job properly. Look at the old HP crystal ovens - dirty great things with loads of insulation inside the outer metal cans.

The OCXO from an HP 55300A GPSDO:

Hi Ceberus,

sorry I don't want to instruct or advice you, may be my english is insufficient to explain my point clear enough.
I don't mean that OCXOs need "cooling" but only the contact to free air.

I was nearly 2 years with the time nuts, there are infinite topics here and in the web. Starting with simple VCXO and later
OCXOs I now have several double oven OCXOs (TRIMBLE). With one I built the high precision time base for my HP53131A
and it keeps it's stability (against my GPSDO) in the limits of the self calibration (about 1mHz @ 10 MHz).

During my way I was in uncountable web boards, read many data sheets and project descriptions.
In the beginning I also expected an improvement by covering the OCXOs but I got the the advice to avoid it.
May be there are OCXOs that benefit from extra shielding but I think if this could help you find some advice in the data sheets
of the manufacturers. If the regulation benefits from some shielding it is done by design as you mentioned.

I run two professional UCCM-GPSDO (most of all china 10 MHz OCXOs and UCCM come from decommissioned
mobile phone stations) with SAMSUNG and TRIMBLE OCXOs but I never saw any extra thermal shielding.
And the fun starts if you try to test your OCXOs for phase noise/Allan deviation ...
But this are my 50 cents, if I was unpolite - sorry!

B.D.

[BU508A]

Cerebus won the Keysight scope ! 

"ONCE and ONCE ONLY" What? That's what you said to post! 

WINNER WINNER CHICKEN DINNER!

  

Congrats Cerebus, enjoy your new toy! 

[bd139]

Yes congratulations. Definitely a better prize than the junk Mail I won 

[tggzzz]

Brown Santa dropped off some new toys today:

-Pat

Nice.

I suppose you ought to invest in a temperature controlled immersion bath now 

Good luck deciding which chemicals to use to clean the contacts; I've never seen an answer I trust.  Looks like they have the "horn" that enables contacts to be made by dipping it in mercury.

[BU508A]

Recently on ebay:

Code: [Select]

10x 0.1R      0.1%   Burster Type 1168
10x 1R        0.1%   Burster Type 1168
10x 10R       0.05%  Burster Type 1166
10x 100R      0.02%  Burster Type 1164
10x 1000R     0.02%  Burster Type 1164
10x 10000R    0.02%  Burster Type 1164
10x 100000R   0.02%  Burster Type 1164


[tggzzz]

Of course if you put a big enough engine on it, you can make bricks and lawnmowers fly.

And pigs, of course.

I know of a place that occasionally launches sheep into the air by accident, but I haven't seen a motor attached to a pig, presumably because the animal welfare people would become interested.

[tggzzz]

Hi Ceberus,

during the last year I also played with different OCXO solutions for GPSDOs. I learned that it's better not to cover the OCXOs with foam because the heating-cooling-regulation needs the convection with free air.
It only makes sense to avoid direct air flow from a vent. All the professional solutions I have seen use the "naked" OCXO.

I have done this only one time since I had a OCXO without Vref output and I used a cheap TL431 for this. I put it at the can of the OCXO and covered it with foam.

I don't know why you'd think that. If the control loop for regulating the temperature of the OCXO was so badly designed that it needed some external cooling to be stable your point would be well made, and the control loop would not be. As it is I've never seen this and wouldn't expect to. If it needed a specific amount of convective cooling the data sheet would have to specify the amount of heat dissipation necessary and again, that is not something that I've ever seen. So I think you're a bit off with the expectation that "the heating-cooling-regulation needs the convection with free air".

In general most ovened things, be they XOs or voltage references benefit from having as much isolation from the local thermal environment as possible. Some ovened references go so far as to place the oven inside a dewar flask ('vacuum' flask). That you don't see it in many commercial designs is probably more likely down to being cheap than being about doing the job properly. Look at the old HP crystal ovens - dirty great things with loads of insulation inside the outer metal cans.

The OCXO from an HP 55300A GPSDO:

Hi Ceberus,

sorry I don't want to instruct or advice you, may be my english is insufficient to explain my point clear enough.
I don't mean that OCXOs need "cooling" but only the contact to free air.

I was nearly 2 years with the time nuts, there are infinite topics here and in the web. Starting with simple VCXO and later
OCXOs I now have several double oven OCXOs (TRIMBLE). With one I built the high precision time base for my HP53131A
and it keeps it's stability (against my GPSDO) in the limits of the self calibration (about 1mHz @ 10 MHz).

During my way I was in uncountable web boards, read many data sheets and project descriptions.
In the beginning I also expected an improvement by covering the OCXOs but I got the the advice to avoid it.
May be there are OCXOs that benefit from extra shielding but I think if this could help you find some advice in the data sheets
of the manufacturers. If the regulation benefits from some shielding it is done by design as you mentioned.

I run two professional UCCM-GPSDO (most of all china 10 MHz OCXOs and UCCM come from decommissioned
mobile phone stations) with SAMSUNG and TRIMBLE OCXOs but I never saw any extra thermal shielding.
And the fun starts if you try to test your OCXOs for phase noise/Allan deviation ...
But this are my 50 cents, if I was unpolite - sorry!

B.D.

I understand your points about control loops, and I would look unfavourably on a temperature controlled component that was insufficiently well insulated to be able to control its own temperature.

I suspect such things would benefit from being screened from variable drafts. That implies a large non-sealed container, e.g. an equipment case.

I have seen reports that portable voltage standards based on zener diodes can show some sensitivity to their orientation - so don't use them lying on their side etc.

[tggzzz]

One of them is weeping oil, so it looks like there will be some teardown pictures at some point.

(The left hand arm is slightly loose where it emerges from the to cap; I'm hoping that it's something that can be easily tightened once the retaining collar has been unscrewed.  Some quick google searching hasn't gotten me any images or exploded views to let me know the internal construction of this kind of standard, so my fingers are crossed that I don't bugger it up.)

There's a thread on this topic: https://www.eevblog.com/forum/metrology/oil-for-a-leaking-tinsley-standard-resistor/msg2761572/#msg2761572

Note that some types of oil have unpleasant additives.

[med6753]

I’m back home and in one piece so far but, to be fair, I haven’t attempted to unload my SUV yet.

Need better pictures ASAP. Including teardown and condition of the insides.

[beanflying]

I’m back home and in one piece so far but, to be fair, I haven’t attempted to unload my SUV yet.

Need better pictures ASAP. Including teardown and condition of the insides.

You just want to enjoy seeing someone elses insides pop out as a virtual Hernia while you nurse yours?   

[Bad_Driver]

Yes, orientation is important for high precision OCXOs as Dave has shown in one of his videos - wrongly named „Measuring elevation with a counter“ or so. The crystals orientation from the cut is interacting with the gravitation.

B.D.

[25 CPS]

I’m back home and in one piece so far but, to be fair, I haven’t attempted to unload my SUV yet.

Need better pictures ASAP. Including teardown and condition of the insides.

You just want to enjoy seeing someone elses insides pop out as a virtual Hernia while you nurse yours?   

I already had two of those back in the 1980s.  It's too recent in memory to make me want to get another.

[Kosmic]

Brown Santa dropped off some new toys today:



-Pat

Lucky for me that seller wouldn't ship to Oz  There has been a few oddball value job lots recently on evilbay.

One of them is weeping oil, so it looks like there will be some teardown pictures at some point.



(The left hand arm is slightly loose where it emerges from the to cap; I'm hoping that it's something that can be easily tightened once the retaining collar has been unscrewed.  Some quick google searching hasn't gotten me any images or exploded views to let me know the internal construction of this kind of standard, so my fingers are crossed that I don't bugger it up.)

-Pat

They are filled with oil and the tops unscrew. We had a chat a while back about it and Equine sourced Mineral Oil seems to be the answer. (Kosmic's idea I think?) They run fine without but it will dampen the thermal rise in use. If you have a 'spare' 1k let me know and we can arrange a subsidy on the lot if you are interested 

You can screw back the arms (need to open the resistor) and the top. Leaking a bit of oil (from the top) is not necessarily a problem. Maybe the hard rubber is a bit stiff after all those years ? as long as the capsule is intact and oil is not coming out when standing.

It's a good idea to change the oil though. It should be replaced with good quality light mineral oil.

Fluke Calibration Philosophy in Practice, page 14:


A cheap source of such oil is horse laxative



I'm also attaching to this post the specsheets for the Leeds & Northrup NBS resistors

[Kosmic]

Brown Santa dropped off some new toys today:

-Pat

Nice.

I suppose you ought to invest in a temperature controlled immersion bath now 

Good luck deciding which chemicals to use to clean the contacts; I've never seen an answer I trust.  Looks like they have the "horn" that enables contacts to be made by dipping it in mercury.

The oil bath is optional with NBS style resistors. Mostly allow you to use higher amps by having better thermal dissipation.

[Cerebus]

Brown Santa dropped off some new toys today:



-Pat

Now you're going to have to use up all your time and TEA money building a temperature controlled oil bath. Bummer. 

[Cerebus]

Cerebus won the Keysight scope ! 

"ONCE and ONCE ONLY" What? That's what you said to post! 

WINNER WINNER CHICKEN DINNER!

Gosh! (As Olivia Coleman would say.) I've been buried in OCXO/GPSDO code fiddling so I haven't even opened my email today so this was the first I've heard of it. Just checked my email and, sure enough, I've got an email from Dave.

[bd139]

Normality resumed here. Back to TE acquisitions 

[tggzzz]

Cerebus won the Keysight scope ! 

"ONCE and ONCE ONLY" What? That's what you said to post! 

WINNER WINNER CHICKEN DINNER!

I don't often get jealous, but I suspect I've turned a shade of pale green.

Definitely "jammy git" award territory.

[mnementh]

Cerebus won the Keysight scope ! 

"ONCE and ONCE ONLY" What? That's what you said to post! 

WINNER WINNER CHICKEN DINNER!

Gosh! (As Olivia Coleman would say.) I've been buried in OCXO/GPSDO code fiddling so I haven't even opened my email today so this was the first I've heard of it. Just checked my email and, sure enough, I've got an email from Dave.

Congratulations, ya manky git!!! 

mnem
*currently trying to unfuckerize a wristwatch*

[beanflying]

Normality resumed here. Back to TE acquisitions 

Nothing here for me just a little NON @Brumby Ozzie enabling

Also local evilbay is trying to sell me a replacement for the lost Gossen but this cutey is in Hamburg so here you go Germans something square boring and of a time eBay auction: #224424609094