Test Equipment Anonymous (TEA) group therapy thread

[Mr. Scram]

I was bidding on a decade resistance box today, but got saved by the ridiculous prices. Some of those boxes go for outright stupid prices.

[bd139]

Yeah they go for insane amounts. No idea why. They’re just some resistors and switches in a damn box.

I have taken to just soldering a pot in and then pulling it and measuring it or just using fixed values. I was going to make one but for the sake of using it once every week or two it’s not worth the time and cost.

[Mr. Scram]

Yeah they go for insane amounts. No idea why. They’re just some resistors and switches in a damn box.

I have taken to just soldering a pot in and then pulling it and measuring it or just using fixed values. I was going to make one but for the sake of using it once every week or two it’s not worth the time and cost.

It seems the ones with single ohm or even tenth ohm scales go for even more money. I'm not that's absolutely necessary, although single ohm would be nice.

I do already own a capacitance box, so having a resistance box should make for some filtering fun. That's pretty much my main concern, plus maybe easily stepping through values to test the multimeters.

[bd139]

I’ve got some 0.1% Dale RN55 resistors for DMM checks. They were a whopping £1 (about $1.25) delivered.

[Mr. Scram]

I’ve got some 0.1% Dale RN55 resistors for DMM checks. They were a whopping £1 (about $1.25) delivered.

Sure, there are other options. However, a lot of the additions to the lab are based on increasing comfort and speed, rather than just capabilities, and a decade resistance box fits that idea nicely.

The only regret I'm really having is not investing in proper kit sooner. I want tools that help me get the job done, rather than tools that need to be fought to get anywhere.

[Specmaster]

Yeah they go for insane amounts. No idea why. They’re just some resistors and switches in a damn box.

I have taken to just soldering a pot in and then pulling it and measuring it or just using fixed values. I was going to make one but for the sake of using it once every week or two it’s not worth the time and cost.

Yes, I've been looking for a while now but they do seem stupid amounts of money, so I'm guessing that they must be equal to or better than .05% resistors in them?

[Mr. Scram]

Yes, I've been looking for a while now but they do seem stupid amounts of money, so I'm guessing that they must be equal to or better than .05% resistors in them?

A lot are 0.1% or even 1%. Granted, you need a handful, it's small scale production and proper switches aren't cheap, but still. Even the Chinese ones are often close to $100.

[Cerebus]

I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.



Those are hermetically sealed foil resistors inside, Vishay HPs, which are the precursor to Vishay VHPs which trip in at the £20-30 level for a single resistor. VHPs are 0.005% tolerance and alter less than 60ppm between -55C and +125C. I won't say the annoying low price I won it for for, but it didn't break 2 figures.

[Mr. Scram]

I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.



Those are hermetically sealed foil resistors inside, Vishay HPs, which are the precursor to Vishay VHPs which trip in at the £20-30 level for a single resistor. VHPs are 0.005% tolerance and alter less than 60ppm between -55C and +125C. I won't say the annoying low price I won it for for, but it didn't break 2 figures.

Nice score! It seems that some listings get a lot of attention, and therefore go for insane prices. Unfortunately, most listings I watch lately seem to be of that type.

[tggzzz]

I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.

Yes, how annoying (for us ).

The nearest I have is a 121.1ohm Dekapot (DP1311), but it has the advantage that the dials go all the way up to 11. It cost all of £10, at a local hamfest.

[Cerebus]

I just missed out on a three decade Dekapot a few weeks back.

[bd139]

Back from my local crap merchant and have scored another Tektronix scope, this time a 465B. This one is sick like the 475 was. Apparently people have seen it and run a mile. However it's not all that bad: the CRT is defocused and to the right and intensity doesn't work. The HT is definitely working though so that's less of a worry. Probably power supply or intensity control shot. Time will tell.  And for less than £30 again.

And thus another thread is born: https://www.eevblog.com/forum/repair/tektronix-465b-repair-97327/

[guido]

The 7A13 is a differential comparator with +-10V internal offset. So you can display a 10V DC signal with  1 mV/div resolution.

Those now too are on my list. 
Small correction however, you said 7804 while mine is 7704A

Keep in mind that the 7A13 is full of very Tek specific relays. With a footprint that prevents an easy replacement. Unfortunately they do fail on a regular basis, specially the double contact ones. In the old days they actually repaired them, using a Dremel to open them. I made two test jigs to test them. Seems to help if you connect them to a FG and let them switch a large number of times.



Tek 7k stuff is addictive. On the bench: 7603 with 7A22, 7A13 and 7B53A. 7623A with 7L5+TG. On cart: 7704A with 7A18, 7S11, 7T11 and 7B70. Then 5 more 7xxx mainframes as spare and a number of parts/fix-up plugins. Like another 7L5 (looking for the big knob assembly), 7A13 without relays (guess why), some more 7A..amps and a number of spare 7B53As. And one self made 7xxx extender cable. About half the mainframes have new PS caps, using adapter pcb's. I had to fix the 7704A a number of times. Bad resistors/arcing in the HV section. Primary bridge rectifier shortened and a shortened tant cap somewhere. Keeps you busy. But all easy fixes.

I have a similar list of TM5xx(x) stuff, next to the regular gear. Yep, I fit in here 

[BU508A]

I was bidding on a decade resistance box today, but got saved by the ridiculous prices. Some of those boxes go for outright stupid prices.

I am in the middle of assembling my own resistor box (seven decades, starting from 0.1 Ohms). It is not super accuate, something between 0.1 and 1% but it fits for my needs. The switches are relays and the value is directly showed with some nice red Kingsight 7-segements LEDs. The value will be set by 7 BCD rotary switches.

Yeah, I know, it is a kind of overkill and not optimal, but I like the fun in assembling it.

If you (people from the forum here) are interested, I'll show (in a separate thread) the schematics and pictures of it.

[bitseeker]

Yeah, I know, it is a kind of overkill and not optimal, but I like the fun in assembling it.

That's what counts!

If you (people from the forum here) are interested, I'll show (in a separate thread) the schematics and pictures of it.

Of course! Was that a trick question?

[bitseeker]

Take a look at what's painted on the top of this Fluke 8800A. Is it a sign?

https://www.ebay.com/itm/Fluke-8800A-Digital-Multimeter-Power-Tested-/232530603798

(Warning: There's a sizable chunk of the side of the case missing.)

[BU508A]

Of course! Was that a trick question?

You'll never know ... 

[bitseeker]

As long as you post the link here, all will be well.

[BU508A]

Take a look at what's painted on the top of this Fluke 8800A. Is it a sign?

If you have ever seen "Sleepless in Seattle" then you'll know: everything could be a "sign" 
(love the scene when they discussing movie scenes  )

[Specmaster]

Take a look at what's painted on the top of this Fluke 8800A. Is it a sign?

https://www.ebay.com/itm/Fluke-8800A-Digital-Multimeter-Power-Tested-/232530603798

(Warning: There's a sizable chunk of the side of the case missing.)

Haha, they even have the cheek to describe it as being in Very good cosmetic condition with no dents or dings, the sign is great though.

[Cubdriver]

Take a look at what's painted on the top of this Fluke 8800A. Is it a sign?

https://www.ebay.com/itm/Fluke-8800A-Digital-Multimeter-Power-Tested-/232530603798

(Warning: There's a sizable chunk of the side of the case missing.)

Haha, they even have the cheek to describe it as being in Very good cosmetic condition with no dents or dings, the sign is great though.

Well, it doesn't have any dents or dings.  They say nothing about it not having a chunk missing...     Besides, that opening helps with cooling!   

(Watching for curiosity's sake, have no intention of attempting to buy it)

-Pat

[Berni]

I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.

[img]

Those are hermetically sealed foil resistors inside, Vishay HPs, which are the precursor to Vishay VHPs which trip in at the £20-30 level for a single resistor. VHPs are 0.005% tolerance and alter less than 60ppm between -55C and +125C. I won't say the annoying low price I won it for for, but it didn't break 2 figures.

[img]

Now that is a true beauty of a resistance box! Amazing bargain there!

I did get a set of DC-20GHz attenuators in the original wooden box with the original factory cal sheet(with data) inside in almost perfect condition for like 50 bucks. They are all N connector tho, would have preferred SMA.

[bd139]

My 6206B is arriving today and I'm suffering from a bad case of late-stage-SAD. I came across this earlier which is a nice board game for those of you anxiously waiting for that wonderful dose of TEA to arrive. Open image in a new tab if you can't read it

[ChrisLX200]

LOL! some of those are too painfully accurate :-) Had the issue of the driver claiming he attempted delivery when no-one was at home... BS.

[bd139]

Yeah I caught the bastard doing that the other day. Made him go back to the van and get it.