Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

   More progress on the Type 191. The dual 40uf/500V caps installed. Did a quick power up check and all is well. Now on to the last one which is going to be a PITA.

Yeah; one advance of the solid-state/computer age (for a while anyways) was the common use of blind nuts in chassis panels like this. Would make this a simple job of unzip a couple screws, pull the wires out with the cap, unsolder and solder to a terminal strip zipped down on one side. Having to get to the nuts on the other side hidden under something else just adds a world of misery to this job.

You MIGHT could get lucky by using a drill to unscrew the screws while pressing against the cap sideways away from the screw to apply levering force so it keeps tension on the nut. Repeat for the other screw, remembering to press laterally away from the screw. Once you have the cap loose, hopefully enough room to work through the hole.

Good hunting my friend!

mnem
*back to the bench*

[med6753]

Bodge alert!  I was able to get the last can unhooked and removed without too much difficulty. But in looking it over rather than go with a terminal strip on the opposite side I would just bodge in the 510uf/50V replacement right on the original ceramic strips. Doesn't look too bad but it's a bodge none the less. But it's secure and I can live with it.



Now what better way to check out a vintage Type 191 than with a vintage 535A? All is well and it works fine. 

[BU508A]

Here is a little update to my Fluke PM6681 counter.
Refernce: https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2871844/#msg2871844

Yesterday, the GPSDO (BG7TBL 2019-08-09) arrived and today I've installed the GPS antenna.
The GPSDO locked to the GPS signal after 2 or 3 minutes and after 20 minutes the internal OCXO
synced to the GPS signal. Now I have a 10MHz signal with an uncertainty of 1*10^-11
I've connected it to the PM6681 as an external reference and adjusted the new OCXO for the Fluke PM6681 which is much stabler (around a factor of 1000) than the internal oscillator.

This is the OCXO. I just bodged a little thermometer to it to see, when the oven temperature stabilises.
Interestingly, the temperature drifts between 44.8°C and 46°C but by the looks, this doesn't affect the stability of the 10MHz.


This is the state after 1.5h cooking:


Edit:
I've also received the prescaler from cojotech (Thank you very much! )
I'll put everything together by tomorrow and will do a little follow-up then here.

Regarding the discord session: I'll try to join, but since some relatives wants to visit us tomorrow I have promised to bake two cakes. So, perhaps I'm a bit busy besides discord.    

[bd139]

Are you sure that is enough zeroes? 

[BU508A]

 

It's the same as with Test Gear: you can't have enough of them! (As long as the leading digit is greater than zero) 

[bitseeker]

Yeah, adding lots of leading zeroes is easy.

[Specmaster]

Unlike the leading digit, it was not as easy getting the last digit to be stable 

[bitseeker]

Something else TEA related for a change , a bit more information on HP serial number prefixes for the older HP/Harrison power supplies with a three part serial number tag

Thanks, David. Added that to the serial number info collection in the POI.

[bd139]

Decided to spend some time working on my gumtree and ebay scrapers this afternoon with the intent of obtaining $$$ and guess what. Gumtree introduced Captchas the bastards 

[Mr. Scram]

Decided to spend some time working on my gumtree and ebay scrapers this afternoon with the intent of obtaining $$$ and guess what. Gumtree introduced Captchas the bastards 

Apparently there are services where people complete captchas on demand. I hear they're cheap but I'm not sure they're cheap enough.

[bd139]

Yeah you can use mechanical turk for it https://www.mturk.com/ but it's not worth writing all the code to extract and aggregate it as it'll be more complicated than the damn scraper 

Edit: also to note I'm not a fan of the idea of using below min wage slavery to do it either.

[Mortymore]

My Fluke counter has more zeros   

[tautech]

Discord in 1 hr !

[Mr. Scram]

Yeah you can use mechanical turk for it https://www.mturk.com/ but it's not worth writing all the code to extract and aggregate it as it'll be more complicated than the damn scraper 

Edit: also to note I'm not a fan of the idea of using below min wage slavery to do it either.

Fair point on slavery. Some restraint is preferred.

[beanflying]

Discord in 1 hr !

Can't I sleep a bit more yet 

[AVGresponding]

Antipodeans eh... if you're not bothering sheep, you're counting 'em!

[beanflying]

I thought the same thing applied to the Welsh and the Scots too

[bd139]

Running late for discord. My mother phoned 

[Cerebus]

I thought the same thing applied to the Welsh and the Scots too

No just the Welsh. The Scots, if they go in for that sort of thing, go for redheads with horns - the Hielan' Coo.



That's Mòrag, you don't get on the wrong side of Mòrag. Not twice anyway.

[mnementh]

As long as it don't have green eyes... 

mnem
moo...?

[ArthurDent]

This is the OCXO. I just bodged a little thermometer to it to see, when the oven temperature stabilises.
Interestingly, the temperature drifts between 44.8°C and 46°C but by the looks, this doesn't affect the stability of the 10MHz.


This is the state after 1.5h cooking:

I put a slightly different timebase (X-72) in one of my Philips/Fluke PM6680B counters.

[Kosmic]

Was previously reaching 965ps on the breadboard. Now with smd components (minus the pcb ) and properly mounted, I get 290ps on a 50\$\Omega\$ load.

First tentative of creating a step. I was targeting 2.(something) nanosecond width. This is with a external 20db attenuator (probably loosing some ps there) since the scope is 5Vrms max on 50\$\Omega\$ load. Also has max 1V /div. I need a built-in attenuator.

[0culus]

Don't you just need to build a bit of a delay line?

Anyway, I may or may not have bought a 3440A nixie tube voltmeter for $30.  It's gone some issues with the mV ranges that I've noted, needs a cal, and the leftmost digit tube is a bit tired; not all digits in that tube fully light it seems. 8 and 2 in particular. But hey, for $30 I can't say no. The tubes by themselves are worth far more and this way they stay in the voltmeter where they belong.  Probably will have to find one extra though.

As always, some RPN porno has been carefully staged for @nixiefreqq. 

[mnementh]

I put a slightly different timebase (X-72) in one of my Philips/Fluke PM6680B counters.   

Excellent bit of McGyver-fyin' there Arthur! 

mnem
"Little does mnem know: That's not actually a X-72 timebase module in there, but rather simply a cheap Somebody Else's Problem Field generator..."

[Kosmic]

Don't you just need to build a bit of a delay line?

Yep, 20cm of coax should give something like 2ns. Then the hard part is trying to make the square wave presentable