Test Equipment Anonymous (TEA) group therapy thread

[m k]

It explains why you mentioned the L1436 connector, they were still made back in 2009 and are the most fragile inside, tiny screws that can easily break off.

I even found few new ones, but from Australia so shipping will be more than nominal.
Search continues.

...snip...

I have one new left & a couple of used ones. Do you want me to find out the costs to send the new one?

David

Yes, very much.
Used one is also very much enough.
I found few used ones from online also but pictures were not promising.
Local dealer had them too, or so I think, can't find them anymore, from browsing history either, maybe better this way, minimum was 4 for a bit under 100€ w/o taxes and shipping.

Few 3P DIN connectors I ordered from China, we'll see.
Even that this some time ago pictured, less than optimal BNC is still in mind.

For Labor I ordered T727 something, from China also.
Not exactly sure how it fits since there seems to be different inserts.
Seems to be also that China is still using the design regularly.
ebay had some too, one was really old side angled version, there ground connection was sort of an external add-on.

Since the connection is the issue here, I got an old 3U subrack case with backplane from DTMF era.
One must wonder how many different alternative standard bus versions have been available.
I wouldn't mind either if somebody enlights some DIN 41612 nuances, like what are different female short side shapes meaning.

PSU sound effect then.
(it is there, turn the volume up, not very steady but it is there)
https://youtu.be/ySSb90bGuEU

Reflection of 1s red blink on left is from the earlier mini scope.
Both outputs are around 200V with 75k resistive load.
Maybe I'm misusing it.
(actual tubes are TG1-0,1/0,3 CCCP)

Power-on lamp was ok, just too oxidised.
Cleaning didn't do much good, it turned on all right but was so bright I had to take it away.
Also forgot it out when packed the machine.
It's a screw model but there's a lock spring inside the apparatus.

https://www.radiomuseum.org/r/laborms_tapegyseg_e_i_feed_transformer_unit_oe_404.html

Some component values.
Grid resistor is 47k/5%/1W, C is 470nF/160V, pot is a wire thingy maxing around 20k and winding feeding it says 0V/20V/40V.
Positive side damping? winding says 30V, C is also 470nF/160V, pot is 33k/2W and diode seems to be Tungsram SIEK2.
LCRC resistor is 220R/5%/6W, C is 2x32uF/450/500V and L is unknown but not very small.
Voltage measurement divider resistors are 75k/1%/2W and spool types around 10R for currents and 350R for voltages.

Both filament voltages are pretty close to 6.3V when input is 220V but secondary 350V is actually around 410V.

[Ice-Tea]

Breaking up a 8714C. So you get pictures.

[dl6lr]

The most impeccable Tek 577 one I've found, too bad that I can't get it, but let's enjoy it together:

https://www.ebay-kleinanzeigen.de/s-anzeige/tektronix-577-curve-tracer-kennlinienschreiber/2257917353-168-6326

I contacted that guy immediately after he posted the ad with €550,-. He responded after two days and increased the price to €750,-. I already had my colleague ready for pick up.

[Peter_O]

The most impeccable Tek 577 one I've found, too bad that I can't get it, but let's enjoy it together:

https://www.ebay-kleinanzeigen.de/s-anzeige/tektronix-577-curve-tracer-kennlinienschreiber/2257917353-168-6326

I contacted that guy immediately after he posted the ad with €550,-. He responded after two days and increased the price to €750,-. I already had my colleague ready for pick up.

Had a same behaviour once with another guy and a 3400A.
He postet it untested for 80 Euros and I immediately made the deal. Then he wrote that he has tested the DVM in the meantime and that it seems to work, and he changed the price to 200 Euros plus shipment.
I explained, that we had made a binding deal already, but that I will not dispute about it to avoid getting bad mood into my hobby.
He got a bad conscience and gave a new price of 160 Euro incl. shipment to me.
My answer was, that this would be a really good price for a working 3400A, but that I - by principle - make no deals with people, who do renegotiate.

In case you had a binding deal already, you could insist.

When your buddy is onsite to fetch it up, the seller might try to increase the price again.

I would forget about it completely.

[DC1MC]

I contacted that guy immediately after he posted the ad with €550,-. He responded after two days and increased the price to €750,-. I already had my colleague ready for pick up.

Really ?!? What an Arschloch  , and full idiot as well, this blatant shite rarely works overall and definitely doesn't in Germany, where "ein Mann, ein Wort" still has some power. But let him wait 750 days, this is no iPhone, I have a feeling that 95% of potential customers customers are here and have seen this asocial behavior.
@dl6lr I still can make him a 500€ 'Angebote and if we meet in the middle (550  ) you can send your friend to pick it up, let me know if I should do it.

 Cheers,
 DC1MC

[Vince]

Hello people,

So here are a few pics of what I picked last Saturday from my 900kms long trip to Bordeaux.

Some context first.  3 and a half years ago I bought my first Tek type 547 hollow state scope from a chap in Bordeaux.
It was quite a trip but I wanted a 547 so bad that when you see one, you go get it. The cost and physical pain that such a trip meant to me, was mitigated by the fact that by some miracle, at the very same time there was also a type 549 (mostly a 547 but with a storage CRT and lower B/W) by some other chap, also for sale in Bordeaux, go figure. So since I also badly wanted a 549, it made the trip worth the expense and trouble to me. 
Anyway, so when I was at the place of the 547 seller, I saw that he had a mega huge house/mansion with two  rooms each the size of my house, filled with vintage stuff 

I didn't even have time to look at it all, nor was it all easily accessible either. However he guided my "tour" of his place, targeting vintage Tek stuff.
He had a scope cart, a 7000 series scope in bad shape, a time mark generator type 180A, a 545A scope in working order and.... some 500 series plugins.... NICE ones !
I like uncommon plug-ins, special purpose ones, anything out of the ordinary that brings some spice to these old scopes. I mean most of my 500 scopes came with a general purpose, mundane dual channel amplifier, either type CA for the older scopes, or the 1A1/1A2 for the more "modern" ones, so to speak. So when I saw that all the plugins he had were much more exciting and rare than a CA/1A2, I wanted them all ! ... but couldn't afford them, I was totally broke back then. I did stretch my budget by 60 Euros to buy his 545A because it would make the trip even more worthwhile, and it's big so can't be sent by post easily, if at all.

So I told him I would buy him all of his plugins and the 180A time mark generator when my finances would be better.
He was super nice and said yeah don't worry I won't sell any of "your" stuff to anybody, I can wait.

Sadly problems in life just kept piling up, it seemed I was cursed. It's only right now, that I found a new job, and that my house construction problems are slowly improving... that I can now at long last buy his stuff ! I kept e-mailing him once or twice a year to stay in touch and tell him how things were going in my life... and I could finally visit him last week-end to conclude our deal... 3.5 years later !
Can you believe he waited that long just to please me ?! He did. In the meantime he sold 90% of his other stuff of course, but he kept his promise and didn't sell his Tek plugins !
Well... he did sell the time mark generator though... because a guy came and offered to buy a couple palettes worth of TE, if he could take the type 180A....
Plus it's my fault,  I told him I wasn't sure about the 180A... saying I liked it, but that I ideally preferred the rack mount version of its little brother... which I never found for sale in the end.
But lucky me as you know, I did eventually find another 180A for sale earlier this year 

So, I came to his house, all the plugins were there, was so happy he kept them all for me, a little treasure...
Then he said come have a look at what else is left, I still have some stuff.
I said oh that looks cool... but I have no money with me, I only took XXX Euros that was agreed for the plugins !
So he said : "It's free for you of course ! Just go have a look, just grab whatever TE you fancy and it's yours ! "
I could not take it all, I have a car not a semi truck, so I had to make choices... even then, said choices didn't fit the car, so I had to remove some stuff from the boot and make a second pass at filtering what I would take home with me. It felt like having to chose between losing my left or right arm 

Then once the car was full and it was almost dark, he said : "hey, forgot, fancy some old electronics magazines ?! "
I said sure, would love to !
Then he took me to a shed hidden between some trees in his gigantic 15,000m2 yard, and hey presto.... A TON of old magazines ! An entire shelving unit packed full of magazines from top to bottom, left to right. enough for it to fill the car in its own right 
It was dark and I had to leave, so no time to take it all out to see what's what and see what I may want to pick, so instead I just grabbed a few piles at random and tried to shove that in what rares interstices were left in the boot ! 
No, all these magazines are still in good shape somehow, no mold no mushrooms no nothing.... the climate is clement in Bordeaux.

So, below are a few pics of what I brought with me.
Sorry for the crappy pictures, but at least it gives you an idea. I will take better pics of the stuff, and mini tear-downs, if you are interested in a particular piece, or in the coming months as I take some of this to the bench to clean them up and test them out.

Here is the list :

Firsts pic, stacked in the wooden shelving unit :

- A few hundreds old electronics magazines, no idea what I have in there exactly for now.

- A little Férisol NA 300A RF mW meter. Not my thing, but many people like this type of TE so since it's small and very light, I thought it could be economical to ship to someone here on TEA. Free to a good home. I guess I can try to tear it down and give it a quick test ride to see if it works.

- A un-indentified blackbox, literally. Took it purely for parts as it looks like some kind of power supply. Two big heat sinks, TO3 power trannies, a bunch of stud diodes, some power WW resistors, at the least, from what I can see from the outside

- A rack mount Philips PM 2440 volt meter, low frequency one I guess (inputs via 4mm jacks). He had 3 of them, had only space for one. I like the design/style of this generation of Philips products, so it was an opportunity to have one finally. I love the large and wide meter scale, and it's like new, and has a mirror. It's a useful bit of kit as well : it's  VTVM, high impedance : 100Meg in DC and 10Meg in AC mode. Wide dynamic range as well. I like it very much, think I will soon put it on the bench and restore it, definitely can be put to use for general work.  It features a "recorder" output, but I don't quite understand what it means in the context of an analog meter.... will need to read the manual, hoping it is actually available that is !

- A rack mount RF VTVM, model 320A made in the USA by " Ballantine Laboratories", maybe our friends from the US know about them ?? 
I am not into RF VTVM usually, don't need them, but this one looked cool to me in rack mount form, looked good quality overall so... I thought well, OK, why not get at least one of this type of TE, maybe one day I will need it and be glad to have one around.  There were two of them, so again had to chose which to take home with me. They had a different paint colour. One was dark grey, the one I picked, and the other one was the more usual light grey. So I went for dark grey, because I prefer dark... Again nice large meter with a like new scale, also featuring a mirror.

- Now for all the Tek plugins, 9 of them :
- Type 81A "adapter" plugin. Rare sight. It's meant to sit inside a type 585 scope (which I have one of). The 585 cannot use the regular 500 plugins because the input impedance of its signal lines is different. So this adapter plugin does the impedance matching and let's you use the vast array of plugins that were made for the 500 scopes. There were next to zero plugins made for the 585 specifically, only a general purpose 2 channel amp... hence the need for this adapter.
- x2 type 'D' : High-gain diff amp, so that I can probe modern switch mode power supplies when fixing them.
- x2 type  'W' comparators
- x2 type  'L' Fast rise pre-amp
- x1 type 'R' uber cool : special plugin to test transistors and diodes ! Complete with its little test fixture and coax cable. 
- x1 type 1L20. THE ONE I absolutely wanted, ultra mega rare impossible to find here. Spectrum analyzer plugin, up to 4+ GHz. I can't afford a modern SA so this is probably the only SA I will ever have in my lab.

All these plug-ins are not rotten ! Like new inside, zero corrosion or mold. The 1L20 does work.... he demonstrated it to me briefly 3+ years ago when I first visited him, plugged into his 545A scope.

So this is in my living room for now....now let's see the next pics, what I piled up in my bedroom :

- Tek 7504 in poor shape, for parts.

- A strange thing, in green colour : " KAY 5070B Rada-Pulser Sr. Pulsed Carrier Generator "
Don't think I will ever use this thing whatever it is... but looked good enough that I wanted to save it, in case someone here might want to give it a good home.

- Singer Gertch 4BR : Phase angle Voltmeter. Looks cool, but it comes with a plugin which basically is a 2,400Hz band pass filter. So quite a narrow use case.... 

- Férisol P201A : 25MHz pulse generator. It's the BOAT ANCHOR in the lower left corner on the floor... it weighs A TON !! I mean you have to trust me... I am used to handling my 30kg 500 Tek scopes, and this Férisol pulse gen is WAY heavier !    I can move it around on short distances.. barely !
I really didn't have the heart to abandon it, because it's a good brand, is general purpose enough to actually serve a useful purpose, and is like new inside out ( we did crack it open, it's very easy to do, just 4 big thumbscrews at the back). This one for sure I will try to get working.

- A couple of old HP 416B meters. I am not into radio stuff, but I think it must be some kind of " SWR " meter. I will most likely never use it, but some of you might. Regardless, I like this style/generation of HP stuff, they look really nice to me, and these two units are brand new up close, museum pieces. So there was no way I would have left them behind (he is getting old and said whatever I don't take with me, will most likely soon be scrapped).
So in this case, I took not one, but the two of them. The are just too nice and valuable (historically I mean... no idea about money). Taking one and leaving one behind to be scrapped.... was just totally unacceptable to me.


So that's it !

Oh wait you say.... on the pics we see something you didn't list ! What about this 502A Tek scope at the top left of the pile ?!

Yes.... talk about destiny.
Remember last december, almost a year ago then, I bought a 502A from a guy who had two of them. He sold me the one in best condition, and I am now trying to fix it. The other one he had, I tried to buy it for parts, but he said someone was already in touch with him about it... some guy who designs and sells tube audio amps, that said he wanted to rip the transformer from the scope to make his audio amp around !   
Broke my heart.

Well believe it or not.... just TWO DAYS before my planned trip to Bordeaux, guess what popped up on Leboncoin.fr ? Yes, that chap relisted his second 502A !  My point being... this guy lives far away, I would never have made the trip for a parts unit in rough shape... but, he lives in a village that's spot on on my way to Bordeaux, half way ! All I had to do is leave the motorway half way, drive only 10+ kms off course to reach that seller, and back onto the motorway heading to Bordeaux ! So getting that 502A cost me nothing trip wise ! 

So I have now THREE 502A !!! 

That's all....

[Vince]

...

[capt bullshot]

Hey Vince,
congrats on your haul 

[Vince]

Just received Zoli's dummy load goodness, as well as some gold plated goodies ! 

Thanks a lot Zoli ! 

Will be building it sometime this week, stay tuned 

[Robert763]

I bought back the HP 5090A from storage, it behaves much the same, loop volts works and a lack of signal, or maybe it's the Philips RF gen that isn't working properly. 



The power indicator is dead, 100Kc output functions OK, but 10Mc output is faulty, after running it for a while, I noticed the mains transformer seemed excessively hot. Checking later the mains power consumption was around 27W, manual states 8W. 

Later I disconnected the secondary from the PSU board, with no load the power only dropped to 21W. 
Think this one is terminal, one secondary winding measured at 39.6V, the other at 22V (must have shorted turns), need to find another one to restore.





Robert do you still have the 5090A & 5090B, would you be interested in selling them to me?

David

Yes I still have them. Not 100% sure of their exact location at the moment  I've been shifting a lot of stuff around. They are pretty heavy to post, do you just want the power transformer?
I'll have a look for them tomorrow, they are in one of 3 places.

[Neomys Sapiens]

Hey Vince,
congrats on your haul 

Same same of course. With the favourable conditions that this guy gave to Vince, it's a pity that he did not have somewhat more current stuff. Or did he, Vince?? We'll chase you back there in no time!
I'm totally not scoring anything at the moment. I wonder who grabbed the 100W Sourcemeter on Ebay...Dang! I was just pondering what to offer to that guy.

[Neomys Sapiens]

Interesting...the SOAR 5430 seems to be another guise of the R&S UDL44/YEW Mod. 7541.
Well, I have one and don't need a second one.
https://www.ebay-kleinanzeigen.de/s-anzeige/soar-5430-multimeter/2257665172-168-7707

[factory]

I bought back the HP 5090A from storage, it behaves much the same, loop volts works and a lack of signal, or maybe it's the Philips RF gen that isn't working properly. 



The power indicator is dead, 100Kc output functions OK, but 10Mc output is faulty, after running it for a while, I noticed the mains transformer seemed excessively hot. Checking later the mains power consumption was around 27W, manual states 8W. 

Later I disconnected the secondary from the PSU board, with no load the power only dropped to 21W. 
Think this one is terminal, one secondary winding measured at 39.6V, the other at 22V (must have shorted turns), need to find another one to restore.





Robert do you still have the 5090A & 5090B, would you be interested in selling them to me?

David

Yes I still have them. Not 100% sure of their exact location at the moment  I've been shifting a lot of stuff around. They are pretty heavy to post, do you just want the power transformer?
I'll have a look for them tomorrow, they are in one of 3 places.

Thanks Robert, complete would be preferable, they are quite small & a bit lighter compared with some other HP TE that arrives here.

The converter board from JLC is now in the UK (with Evri) , still need to order a couple of parts from Mouser for it.

David

[Robert763]

The 5090s are not in the first (easy) location so they are in one of two places that will require a bit of TE Jenga to get to where they are in those spaces.

[Vince]

Hey Vince,
congrats on your haul 

Same same of course. With the favourable conditions that this guy gave to Vince, it's a pity that he did not have somewhat more current stuff. Or did he, Vince?? We'll chase you back there in no time!
I'm totally not scoring anything at the moment. I wonder who grabbed the 100W Sourcemeter on Ebay...Dang! I was just pondering what to offer to that guy.

Nope, no modern gear there !

Guy is a 72 yo retired dentist.  Electronics was his hobby so he built his lab in the '60s, at which point he started buying every issue of every electronics mag, hence the huge collection in that shed.
His lab today still looks like what must have been his first lab 50+ years ago, I would say !
The only modern / solid state thing I could spot, was his sig gen. He started with a small analog Wavetek one, then later he upgraded to .. still a small/compact Wavetek one, but digital, with fancy things like an LCD screen and push buttons, even BNC connectors rather thanUHF, modern I told ya ! 

Nope, almost all hollow-state technology.

While I am here I may give some more info about this haul, and why it all looks in tip top shape inside out.
He lives in Bordeaux, where Dassault aviation has their main plant. In the '90s Dassault cleared his facility of all the old stuff. Dentist came with a lorry and splashed the cash to buy all of it !
Then he piled everything up in a couple extensions of his house, so it stayed protected from the elements, and since the weather there is clement and warm, moisture and mold never developed. The guts of all these antiques are still sparkling new inside, incredible. Some of the stuff is branded Aerospatiale instead (like the Singer phase  voltmeter).

He also has one mega big huge Dassault specific, most likely developed in house, bit of kit. It's so special and big that it's worth making another 150 Euro trip down there just to get that one thing !
He said I could have it as well...  I said I don't have the space in the house, but as soon as the garage will be erected, I would come to pick it up ! However by the looks of it, building the garage will require two full years, but more like 3.... so it's a bit too early to tell you what it is, sorry !! 

[dl6lr]

I contacted that guy immediately after he posted the ad with €550,-. He responded after two days and increased the price to €750,-. I already had my colleague ready for pick up.

Really ?!? What an Arschloch  , and full idiot as well, this blatant shite rarely works overall and definitely doesn't in Germany, where "ein Mann, ein Wort" still has some power. But let him wait 750 days, this is no iPhone, I have a feeling that 95% of potential customers customers are here and have seen this asocial behavior.
@dl6lr I still can make him a 500€ 'Angebote and if we meet in the middle (550  ) you can send your friend to pick it up, let me know if I should do it.

 Cheers,
 DC1MC

Go ahead, try mentioning you have seen the ad for €550 VB and you are referring to this offer. I am still unsure whether I will contact him again. I will send you a PM with some details. eBay KA is a strange site where you cannot see the history of an ad.

[factory]

It explains why you mentioned the L1436 connector, they were still made back in 2009 and are the most fragile inside, tiny screws that can easily break off.

I even found few new ones, but from Australia so shipping will be more than nominal.
Search continues.

...snip...

I have one new left & a couple of used ones. Do you want me to find out the costs to send the new one?

David

Yes, very much.
Used one is also very much enough.
I found few used ones from online also but pictures were not promising.
Local dealer had them too, or so I think, can't find them anymore, from browsing history either, maybe better this way, minimum was 4 for a bit under 100€ w/o taxes and shipping.

Few 3P DIN connectors I ordered from China, we'll see.
Even that this some time ago pictured, less than optimal BNC is still in mind.

For Labor I ordered T727 something, from China also.
Not exactly sure how it fits since there seems to be different inserts.
Seems to be also that China is still using the design regularly.
ebay had some too, one was really old side angled version, there ground connection was sort of an external add-on.

...snip...

Should between £3.25 to £4.60, depending on packaging thickness & weight, need to find something suitable.

Here is why sending a new one would be best, cannot remove the last wire. 


Seems the AVO DMM uses the same DIN connector for the DC power input, as the Advance DMM2, this one came with the AVO, pictures attached.

David

[factory]

The 5090s are not in the first (easy) location so they are in one of two places that will require a bit of TE Jenga to get to where they are in those spaces.

Thank you for looking, have the same TE Jenga problem here, it's slowly being solved now I have a larger rented storage unit (yes it's expensive, but not as expensive as a getting a mortgage ATM).

David

[DC1MC]

...
Go ahead, try mentioning you have seen the ad for €550 VB and you are referring to this offer. I am still unsure whether I will contact him again. I will send you a PM with some details. eBay KA is a strange site where you cannot see the history of an ad.

PM sent, details will follow, keep the Abhlungfreund in standby 

[Vince]

I'm a bit late to this but for a load capable of what vince needs just 3 IRF603s on a decent heatsink and a psu. Tie the 3 drains (easy don't use insulators but remember heatsink is "hot") for load positive and the 3 sources together for common. Put a 100R at each gate (short lead to gate, this is to stop oscillation) tie the other end of 3 resistors together and put a 4k7 from there to the common sources (acts as pull down to turn MOSFETs off). Then you just put a low voltage PSU across the 4k7. Increasing the voltage increases the lood current.
All the action happens between about 3 and 5V on the gates so fine control is needed. Don't exceed 15V on the gate or you will blow it.
As an alternative to the variable supply you can use a 9V battery and a 10K 10 turn pot. Don't fit the 4k7, tie the wiper to the gate resistors. battery negative and pot CCW end to source connection, battery positive to pot CW end via on/off switch. 

Robert G8RPI.

Geez I am motivated this evening !  It's 23H15 I am tired and soon to go to bed, but I managed to do something cool from start to finish this evening, somehow 

I built / wired the quick 'n dirty load Robert described above. I followed strictly, because I trust him ! 
I went for the 9V battery operated variant, because it's more convenient, doesn't need to be tied to a power supply, and Zoli sent me 9V connectors as part of the goodies ! 

Found a decent looking heat sink. Drilled 3 holes in it for the 3 IRF603.
My drill bits are worse nothing, brand new but can't even make a 2.5 hole in aluminium.... they are Tivoly, a French brand supposedly decent. Well the drill bit kit I bought from them in a H/W  store is worth shit ! However at Airbus they use Tivoly as well and the guys told me they get about 5000 holes out of each standard HSS bit, in thin aluminium sheet... so I guess there is" Tivoly " and... "Tivoly " 

Anyway, I eventually manged to drill these bloody holes. Put self tapers, the trannies are going nowhere. Yes, I put a dab of my 15 year old expired heat sink compound syringe. Need to buy some new stuff... for now I managed by squeezing some out and mixing it, otherwise there some kind of clear liquid that separates from the white thicker stuff. Anyway, it did the job it seems...

Then I got lucky and found in my stock of old junk, a lovely panel mount 10 turn 10K pot as Robert advised.
I knew all my junk would get used... ONE DAY ! This day has finally come, time to celebrate !   

Then I tested on my lab supply, trying to mimic what the load would have to work with when I get to work on the PSU I need to fix/test.
That is, the PSU is a bit less than 11V, and rated at 5.1A.  So I set the lab supply to that, and put both outputs in // which would give me a bit more than 5A, perfect.

Then I set a DMM, the Fluke 11, to monitor the gate voltage, and another DMM next to it, a Metrix MX54, to monitor the current.
Then I took some test points and drew a graph, below.
As Robert said, all the action is between about 3 and 5V. Indeed.

As you can see, it starts conducting at about 3.25V (I get 2mA) ten starting from 3.75V or so, it goes exponential. However the 10 turn pot is perfect and I can get over 5A and am able to finely/easily control the amount of current I want.

I played maybe 15 minutes with it, and the heatsink got only warm to the touch, no more. and I didn't observe any thermal runaway, the MOSFETs were stable/safe.

So in short it's a complete success ! Thanks Robert ! 

So to anyone out there looking for a cheap quick and dirty load like I was.... it an be THAT simple and cheap, yet still works fine for basic usage like I need here !   

[tggzzz]

Want to test the linearity of your DVM?
Or, if you have a stable known HV source, calibrate your DVM?

Here's just what you need: a classic Julie Research Labs VDR106/ 6-decade Kelvin Varley Divider. Even if you took the cover off, there wouldn't be much to see since the first few decades are inside an oil bath. Looks like it has been bashed a bit, since there are missing knobs and it isn't in a wooden case.
https://www.ebay.co.uk/itm/125603063136

No, I'm not interested. I have the 7-decade variant, complete and in a case. Lovely instrument. And mine only cost 15% of that OBO price When I sell it, I'll have to ship the case and guts separately, in order to avoid busting the shipping weight limits

[Robert763]

Glad it worked for you Vince.
The control isn't really exponential, it just starts at about a third of the travel of the pot. If you put a 2k7 or 3k3 resistor between the potentiometer CCW end and common you will get a better range of control over the mechanical range of the potentiometer. (minimum gate voltage will be about 2.5 to 3V)

[factory]

Want to test the linearity of your DVM?
Or, if you have a stable known HV source, calibrate your DVM?

Here's just what you need: a classic Julie Research Labs VDR106/ 6-decade Kelvin Varley Divider. Even if you took the cover off, there wouldn't be much to see since the first few decades are inside an oil bath. Looks like it has been bashed a bit, since there are missing knobs and it isn't in a wooden case.
https://www.ebay.co.uk/itm/125603063136

No, I'm not interested. I have the 7-decade variant, complete and in a case. Lovely instrument. And mine only cost 15% of that OBO price When I sell it, I'll have to ship the case and guts separately, in order to avoid busting the shipping weight limits

Way out of my price range too, also note (for anyone outside of the US) that if Global Shipping (GSP) aka Pitney Bowes find out it contains oil, it will be deemed a restricted item & will be sent for destruction  . That is on top of the usual size, weight and price limits, that vary for different countries.

David

[Robert763]

Nice KVD though. I have the seven decade version (VDR106/7) in the wooden case. I paid £0 for it. Basically just had to convince the previous keeper that I knew what it was and how to use it. More reliable than the Fluke 720 due to no presets  and much simplier switching. Calibration check is every 5 years (for 1ppm) and just needs 11 reasonably well matched 10 k resistors. A method recognised by the NBS as more accurate than direct comparison to their primary standard voltage divider.

[Vince]

Geez, just back from work, checking Leboncoin.fr , what do I see ?! FRUSTRATION !! Nothing but ... FRUSTRATION !

I just got that 502A last week-end, 75 Euros for a rough one, and today there is another 502A, a rare event in its own right so that's cool, mint looking for only 25 Euros ! But local pick-up only of course, and of course seller is at the other end of the country ! 

https://www.leboncoin.fr/collection/2251203109.htm


Then, even worse....

That really nice Rochar Neeksee DMM Factory just found, that I have never seen before, guess what ? YES, one just popped here today ! You just can't make that up ! And only 10 Euros as well, not the usual 100/150 BS !! BUT !!!.... the very title of the ad says it's reserved for some guy by the name of " Rémy " already !!! 

https://www.leboncoin.fr/collection/2251260020.htm