Test Equipment Anonymous (TEA) group therapy thread

[DC1MC]

Ok well today’s task went to shit. I was going to start measuring all these crystals. Managed to get nowhere. Went for an amble, did some shopping and generally got sod all done.

Reminder: Discord this UTC evening 

I also need to measure the motional parameters of 2-300 crystals, mostly form Golledge and Russia, but I've hit the following snag, the bloody Colpitts oscillator (the one with switchable series cap for determining ser/par resonance) it overloads the crystal (almost 9Vpp  ) and creates a huge short term frequency instability, and I want to get them into 10-20Hz tolerance pools for my filters, combined with the fact that they're freaking ultra sensitive to temperature (if you touch them with your hand while inserting in the socket, they drift, I needed to use a plastic SMD tweezers) makes life miserable  .

Does anyone have an idea of an oscillator that loads the crystal a bit less ?

 Thanks,
 DC1MC

Why dont you measure them in an IEC444 test fixture on a VNA ?

If it needs to be measured in an oscillator, the following caveats apply:

- never overrun maximum crystal power (thats a few ten microwatts, normally). Reasons: Nonlinear effects (pulling), heating,
  in worst case electrode damage, permanent frequency change or death.
- Your oscillator needs limiting. Simple way: Schottky diode from AC base to ground.
  Better: power regulator. Pick off Colpitts output, use AD8307 log detector and op amp regulator to drive base bias.
  Advantage: power level can be accurately chosen and stabilized.

Regards, 73
  Wolfgang DL1DWG

Well, I don't use a VNA and a IEC444 test fixture, mostly because I don't have them , and also I have a bit of doubt that NanoVNA clone of a clone of a clone... that I can find around will have the necessary precision for sorting in a 10-20Hz range or better, I may be of course wrong, but this is it, I still don't have any of this.
I new about the the maximum power and overdriving issues, but I've thought that the people publishing these papers already designed these schematics with these considerations in mind, it seems that I was wrong as my mouth fell open when using 12V power supply for the whole test setup I've seen almost 9Vpp on the crystal terminals, I was expecting something like 0.5Vpp or such, no wonder that the drift was crazy.
Anyways reducing the supply voltage didn't change too much and around 5-6V it just stop oscillating with the current components, but just cut it abruptly instead of falling linearly.
I didn't want to  put more capacity in parallel with the crystal and add more thermal instability with the diodes, but the variable biasing idea sounds cool, as the crystals are theoretically identical, even from the same manufacturing lot, it may be possible to get away with a trimmer for a specific lot instead of AD8307, or ?

Any acctual schematic, paper and such will be most appreciated.

 73 de DC1MC

[mnementh]

   


   

This pleases me. Quick & dirty power-up with the 15 Dollah CV/CC PSU. Initial draw ~480mA, settled down to ~210mA after a couple minutes & metal can warm to touch. TinySA shows considerable noise floor; this was expected with above PSU. Sitting right at 10.000MHz w/adj at 0.0011V; of course, resolution of TinySA is not exactly intended for this kind of testing other than signs of life as seen here. 

A'aight. Parts for my Fatbike have finally arrived; time to go put the plucking thing back together.

Cheers!

mnem
 

[Brumby]

For those of us who wanted some OCXO playthings but don't feel the NEED for 10. This seller has a twofor sale reduced for 3 hours more eBay auction: #143779790317 now for the waiting...... 

You rat bastard.   I stayed away because of the prices for 10 - but now I am waiting on two pair ..... all thanks to you.

Harrumph! *crosses arms and glowers*

See how you ozzies are!!! I posted that same exact listing 2 weeks ago when I bought mine... at the same price!!! 

mnem
*toddles off to nuke a bicycle headlamp*

In TEA years that is lifetimes and likely 30 pages ago add to that the Server Dumpster fire hiatus and my 50+ year old brain .....

And most of all Evilbay recommended it as I looked at the 10 buy listing  a second time

Mnem - don't feel too badly about that.  Your contribution came in the early days of the exchanges where I had "switched off" to that particular subject.  Bean came along later, when my guard was down .... and now I'm seeing GPSDO references everywhere I look!!

It seems timenuttery is now seeping into my consciousness.    Oh, hell. 

[Cerebus]

Its 24degC outside, I'm drinking a Harp and doing BBQ. Life is good 

Commiserations on it being Harp. 

Can you really still get that stuff? I haven't seen that on a pump or even in a can in the UK for years. Given the swill that a worrying number of Britons will drink under the label "lager" it might be surprising that we've given it the cold shoulder, but that we have.

[Kosmic]

Its 24degC outside, I'm drinking a Harp and doing BBQ. Life is good 

Commiserations on it being Harp. 

Can you really still get that stuff? I haven't seen that on a pump or even in a can in the UK for years. Given the swill that a worrying number of Britons will drink under the label "lager" it might be surprising that we've given it the cold shoulder, but that we have.

Yep quite easy to find over here. Directly imported from Ireland.



They come in those big can (500ml) and fit perfectly in a pint glass.

[tggzzz]

Commiserations on it being Harp. 

Can you really still get that stuff? I haven't seen that on a pump or even in a can in the UK for years. Given the swill that a worrying number of Britons will drink under the label "lager" it might be surprising that we've given it the cold shoulder, but that we have.

It is probably better than some other stuff on that continent; Budwiser isn't good but it positively eclipses Coors.

Whenever I see a Coors all I think about is the CO₂ emitted transporting that gnats' piss around. Come to think of it, gnats' piss probably has more flavour.

[bd139]

Harp is dead in the UK since tesco introduced “value lager”. Also surprisingly I found out that white lightning, favourite of tramps, is now somewhat respected and the tramps are drinking strongbow ?!???

[tggzzz]

Harp is dead in the UK since tesco introduced “value lager”. Also surprisingly I found out that white lightning, favourite of tramps, is now somewhat respected and the tramps are drinking strongbow ?!???

Or hand cleanser from hospitals.

I wouldn't know anout Tesco; I hate them. A couple of months ago a foolishly bought an "extra special" haddock risotto ready meal for £0.40. On trying it, it fell into the category of Asda ready meals, i.e. "do I want to finish this".

[bd139]

Well that explains the signs on the sanitiser dispensers at my local hospital

[McBryce]

Harp is dead in the UK since tesco introduced “value lager”. Also surprisingly I found out that white lightning, favourite of tramps, is now somewhat respected and the tramps are drinking strongbow ?!???

I didn't know Harp still exists at all. In Ireland it was the beer that only the very oldest Pub guests drank. In Germany the "Under the bridge" / "Down by the canal" and lorry drivers favourite is Faxe Bier and it comes in 1 Litre cans!?

McBryce.

[factory]

Its 24degC outside, I'm drinking a Harp and doing BBQ. Life is good 

With the eevblog servers as they are at the moment, that picture and the one from Mnem below your post loaded like the bad old days of the web. 

David

[bd139]

Hey at least it did load. All I get half the time is the nginx 502 page.

This is irritating as well because I spend half my day at work making sure no one gets to see that 

[tautech]

Hey at least it did load. All I get half the time is the nginx 502 page.

This is irritating as well because I spend half my day at work making sure no one gets to see that 

Yep, Dave changed hosters from one lot of clowns to another lot of clowns for less 502's. 
And it seems they can't be stuffed working weekends to get things sorted.

[bd139]

That’s not the hosters. That’s the config and architecture.

Usually a bunch of php FPM processes that serve pages. In front of that is the nginx reverse proxy. The FPM processes are dying or throwing errors. nginx is reporting that to us as 502’s. That’s entirely above the colo’s responsibility.

I’m not sure what the traffic is like but I suspect this is not enough capacity or too much capacity being used by the forum.

[Brumby]

The forum, driven by its users, uses just the right amount of resources.

We would never dump excessive loads on a server - would we!   

[tggzzz]

Well that explains the signs on the sanitiser dispensers at my local hospital

Dr Phil Hammond[1] noted the joke was that pre-covid people nicked the hand sanitisers to drink, but a year ago they nicked them to use.

[1] a local GP, of "Struck off and Die", HIGNFY, and "MD" in Private Eye fame. Worth seeing his standup stage show; if you sit near the front be prepared to be part of it

[factory]

Reasonable priced hp 428B with probe in the US for anyone interested (US only).
https://www.ebay.com/itm/203343622823


Forgot to post this last week, job lot of vintage boat sinker grade TEA (in the US) including; a hp 738BR, 200SR, 739AR voltmeter calibration set (and yes hp did offer these three together in a rack as K02-738BR, first one I've seen for sale), Genrad capacitor measuring rack, Fluke 760A meter calibrator and another rack of cal standards? from Optimation Inc that I don't recognise.
https://www.ebay.com/itm/353436335733




David

[xrunner]

The forum, driven by its users, uses just the right amount of resources.

We would never dump excessive loads on a server - would we!   

ONLY if needed, would we do that. In no other circumstance otherwise, as we always try to conserve bandwidth because we are not the only users here.

 

[med6753]

Well that explains the signs on the sanitiser dispensers at my local hospital

No such signs here that I've seen. I guess our drunks are smarter or perhaps they can't read. And that is surprising considering one of our favorite past times is to sue people/companies. After all, we need printed in plain sight "coffee is hot" 

[Robert763]

Well that explains the signs on the sanitiser dispensers at my local hospital

No such signs here that I've seen. I guess our drunks are smarter or perhaps they can't read. And that is surprising considering one of our favorite past times is to sue people/companies. After all, we need printed in plain sight "coffee is hot" 

And the flip side is you can buy "rust stain remover" that contains hydrofluoric acid 
www.amazon.com/Whink-1281-10OZ-Stain-Remover/product-reviews/B000LNQNM0?reviewerType=all_reviews

[Kosmic]

Commiserations on it being Harp. 

Can you really still get that stuff? I haven't seen that on a pump or even in a can in the UK for years. Given the swill that a worrying number of Britons will drink under the label "lager" it might be surprising that we've given it the cold shoulder, but that we have.

It is probably better than some other stuff on that continent; Budwiser isn't good but it positively eclipses Coors.

Whenever I see a Coors all I think about is the CO₂ emitted transporting that gnats' piss around. Come to think of it, gnats' piss probably has more flavour.

Yes we got a lot worst. But it's principally me being lazy and only went to the convenience store near my place where choice is limited.

[med6753]

Want some true American piss in a can with a dash of CO2?

Genesse Beer from Rochester, NY. This was (and still is) the cheap stuff when as kids all you wanted was to get shit faced on a budget. Taste was purely secondary.

[beanflying]

I think I would rather drink the HF loaded Drain cleaner than most of the Beers mentioned above 

Seriously too  does Amazon think letting that sh1t be sold on a website to the Mass MORONS as a customer base is a reasonable thing 

[bd139]

Want some true American piss in a can with a dash of CO2?

Genesse Beer from Rochester, NY. This was (and still is) the cheap stuff when as kids all you wanted was to get shit faced on a budget. Taste was purely secondary.

They wouldn't sell us anything alcoholic when i was a kid. Fireworks, dangerous chemicals yes, but alcohol no.

So we bought cartons of apple juice, bags of sugar, bread yeast and bottles of cheap soda and made our own  . If you boil all the preservatives out of the apple juice it makes fairly good alcohol. Enough to get shitfaced on

[med6753]

Want some true American piss in a can with a dash of CO2?

Genesse Beer from Rochester, NY. This was (and still is) the cheap stuff when as kids all you wanted was to get shit faced on a budget. Taste was purely secondary.

They wouldn't sell us anything alcoholic when i was a kid. Fireworks, dangerous chemicals yes, but alcohol no.

So we bought cartons of apple juice, bags of sugar, bread yeast and bottles of cheap soda and made our own  . If you boil all the preservatives out of the apple juice it makes fairly good alcohol. Enough to get shitfaced on

Yes, finding a store willing to sell or get someone of age to buy was always problematic but we found a way. 

Edit...back then legal drinking age in NYS was 18 (now 21) and I did get served in a bar once at 17 no questions asked.