Test Equipment Anonymous (TEA) group therapy thread

[Vgkid]

In a land devoid of T&M gear a tek 7704a appears, I don't think I want it(no room), but it does look interesting. 7a22/7b92/7ct1n plugins, all for 150. worth it??? providing it is still for sale

[med6753]

In a land devoid of T&M gear a tek 7704a appears, I don't think I want it(no room), but it does look interesting. 7a22/7b92/7ct1n plugins, all for 150. worth it??? providing it is still for sale

If it works and it includes the plug-ins then $150 USD is actually a very reasonable price. It's a 200 MHz scope and figure typically $1 USD/MHz so it's cheaper than normal.

[Mr. Scram]

In a land devoid of T&M gear a tek 7704a appears, I don't think I want it(no room), but it does look interesting. 7a22/7b92/7ct1n plugins, all for 150. worth it??? providing it is still for sale

[Vgkid]

If they still have it , I could recoup my money on the plug ins.

[0culus]

In a land devoid of T&M gear a tek 7704a appears, I don't think I want it(no room), but it does look interesting. 7a22/7b92/7ct1n plugins, all for 150. worth it??? providing it is still for sale

I recently grabbed a very well kept 7104 from auction with 2x7A29 vertical amps and the 7B15/7B10 timebases for $125. I'd say that's a very reasonable price, easy to justify even if work is required. Especially that curve tracer plugin...those aren't particularly common and they seem to fetch a lot of money on fleabay, certainly well more than $150.

[mnementh]

   https://antiqueradios.com/forums/viewtopic.php?f=8&t=177192

Don't git any on ya. 

mnem
I don't always put something down here.

[Specmaster]

He's got a few he's shifting. I did a few checks after noticing that. They're all the same condition.

Worst case I get a discount 

You might find this of interest for the future https://xdevs.com/fix/hp34401a/

[bd139]

Yeah been through that one already. Know thy quarry should be a motto before a TE purchase   

[Specmaster]

(Attachment Link)    https://antiqueradios.com/forums/viewtopic.php?f=8&t=177192

Don't git any on ya. 

mnem
I don't always put something down here.

Another mass shooting in your neck of the woods then, must be the heat thats cooking everyone's brain, bet you're real glad to be getting the hell  out of Tejas eh?

[Specmaster]

Yeah been through that one already. Know thy quarry should be a motto before a TE purchase   

Yep, thats what I try to do where ever possible and of course access to manuals is another, learnt my lesson with that bloody Sharetree signal generator 

[bd139]

Yep. I’m going to see if I can find a printed service manual for this as I’m getting OCD about it. I notice in Art of Electronics 3e there are design notes about the front end of the meter as well.

On the paying for it front, the minor credit card deficit from buying has been resolved over the last 12 hours by two eBay sales so I’m still in the black. Woohoo 

Edit: next thing to pounce on is an E3631A if I can find one that isn't terribly overpriced 

[factory]

Nice haul, wch.  I got a pair of 8443As in a lot I snagged a few years ago.  Haven't opened one up as they seem to work (the counter part, anyway), and I haven't had time to poke and prod.  Nice, solid seeming instruments for sure.



-Pat

I haven't done much with mine either, other than power it up and have a quick look inside.


One of the displays has two digits lit at once.
I'm hoping it's the tube that has an internal short & not the driver IC. As I have plenty of spare tubes on some Racal boards I bought years ago.


They also have a small cooling fan for the counter section.


A 1MHz Ovenaire crystal oscillator is squeezed in at the back.


David

[mansaxel]

That said... you are aware that these high-impedance, high-digit meters are generally a lot more sensitive to noise than your typical portable, right? Even a good one like a 189...?

mnem
mrrp?

An Avometer, a Hartmann & Braun Elavi 4 or a Simpson 2xx usually give stable, nice, comforting values, and the movement keeps the jitter away, at that.  There is some thing to be said for fully-analog non-sampling low-impedance meters. Precision, and influence on the DUT, OTOH...

[bd139]

... and it is awesome that you could get that close to a Spitfire and a Harrier.

Many of our museums are like that.

For aircraft, goto Duxford (bonus points for arriving in a DC3 ) and RAF Cosford (and Maybe RAF Hendon, but I haven't been there).

Manchester's Science Museum has a superb Shackleton, a  Spitfire, MXY-7 Ohka (kamikaze), and a replica of Baby.

Another notable museum (Pitt Rivers) has real shrunken heads from the Amazon, mummified babies, and you can pull open the cabinet drawers.

And I won't bother to mention TNMoC yet again!

Ob SR71 porn at Duxford:

Duxford is pretty good. My sister had her wedding reception there on the museum floor.  It's the only time I've seen two shirtless feral kids beating the shit out of a guy dressed as a minion underneath Concorde  

That said... you are aware that these high-impedance, high-digit meters are generally a lot more sensitive to noise than your typical portable, right? Even a good one like a 189...?

mnem
mrrp?

An Avometer, a Hartmann & Braun Elavi 4 or a Simpson 2xx usually give stable, nice, comforting values, and the movement keeps the jitter away, at that.  There is some thing to be said for fully-analog non-sampling low-impedance meters. Precision, and influence on the DUT, OTOH...

Prefer the HP 427A for that, however you can get your lazy response up to spec with an RC filter between the meter and the DUT. You just need to ramp up the settling time to have the same effect basically.

[nixiefreqq]

damn dragon ..... he asked an innocent question about my k20 hp5280 and almost drove me nuts for a week.

he wanted to know what the thumbwheels did.  well they set the gate time in uSec.  but then i discovered that the MSD thumbwheel did not work. 

tracked it to a dead 1820-0732 on the option board.  what is an 1820-0732?  since i don't have a manual for the k20 and can't  find the pin outs for the IC on the interweb.....who the fuck knows what it really is?

did some tracing on the board and snooped around with a scope and decided it is a preset counter (set to be a down counter it turns out....well yeah....that is only logical after you noodle it out).  ordered a down counter and worked up a three IC replacement for the one mystery chip.  (ugly as a dog turd, but it works)

success!  here you see it counting a 1 Mhz signal from an 8640b with the gate time set for 456789 uSec. 

[worsthorse]

Nice haul, wch.  I got a pair of 8443As in a lot I snagged a few years ago.  Haven't opened one up as they seem to work (the counter part, anyway), and I haven't had time to poke and prod.  Nice, solid seeming instruments for sure.



-Pat

I haven't done much with mine either, other than power it up and have a quick look inside.



A 1MHz Ovenaire crystal oscillator is squeezed in at the back.

David

I powered mine up yesterday. The counter doesn't light up, though the power light and fan come on, so this one needs some work. Trouble is, I have to buy an entire HP spectrum analyzer to test the damn thing.  I can't see that happening.  Well, I can see that happening but I am going to try and resist. 

[BU508A]

damn dragon ..... he asked an innocent question about my k20 hp5280 and almost drove me nuts for a week.

he wanted to know what the thumbwheels did.  well they set the gate time in uSec.  but then i discovered that the MSD thumbwheel did not work. 

tracked it to a dead 1820-0732 on the option board.  what is an 1820-0732?  since i don't have a manual for the k20 and can't  find the pin outs for the IC on the interweb.....who the fuck knows what it really is?

did some tracing on the board and snooped around with a scope and decided it is a preset counter (set to be a down counter it turns out....well yeah....that is only logical after you noodle it out).  ordered a down counter and worked up a three IC replacement for the one mystery chip.  (ugly as a dog turd, but it works)

sucess!  here you see it counting a 1 Mhz signal from an 8640b with the gate time set for 456789 uSec.

 

That is a pretty cool repair!     Thanks for sharing it.

Well done!

[nixiefreqq]

just noticed i have two stars and stripes.

hmmmmm.  wonder if the dragon has one with stars and stripes and one with a maple leaf?

[worsthorse]

Does anyone here have a stash of 0.1% resistors that they'd be willing to plunder and sell me a few? I'd like to build a little simple board for testing the rest of the DMMs I have stashed here, so a set of  1, 10, 100, 1000, 10K, 100K, 1M, 10M resistors would be dandy. I could also use just the 1, 10, 1M and 10M in conjunction with the my DMMcheck.

I know. I know. This is how it begins.   

[bd139]

Does anyone here have a stash of 0.1% resistors that they'd be willing to plunder and sell me a few? I'd like to build a little simple board for testing the rest of the DMMs I have stashed here, so a set of  1, 10, 100, 1000, 10K, 100K, 1M, 10M resistors would be dandy. I could also use just the 1, 10, 1M and 10M in conjunction with the DMMcheck.

I know. I know. This is how it begins.   

I bought one of each from RS in the Vishay RN55C or RN55D series for this job.  They are milspec ones.

[worsthorse]

Does anyone here have a stash of 0.1% resistors that they'd be willing to plunder and sell me a few? I'd like to build a little simple board for testing the rest of the DMMs I have stashed here, so a set of  1, 10, 100, 1000, 10K, 100K, 1M, 10M resistors would be dandy. I could also use just the 1, 10, 1M and 10M in conjunction with the DMMcheck.

I know. I know. This is how it begins.   

I bought one of each from RS in the Vishay RN55C or RN55D series for this job.  They are milspec ones.

BD, I did a quick search yesterday and they all seemed to have minimum quantity orders.  I will assume I missed something and go look again, more carefully...

edit:  found them all on mouser this morning in about two mintues.  thanks BD. (note to self: limit use of mental faculties while on otc cold medication)

[bd139]

They sell those in one off quantities usually or at least here. Also they do some from TE Connectivity as well.

They’re not cheap but cheaper than buying ten

Found one from the series: https://de.rs-online.com/web/p/widerstande-durchsteckmontage/8307431/

Cheaper than here. £1.20 a go here. €0.73 there both inc tax

Datasheet here: https://www.vishay.com/docs/31027/cmfmil.pdf

The CMF ones are the same. The RN ones are just derated heavily for mil stuff. I used to solder the bastard things in for a living

[med6753]

damn dragon ..... he asked an innocent question about my k20 hp5280 and almost drove me nuts for a week.

he wanted to know what the thumbwheels did.  well they set the gate time in uSec.  but then i discovered that the MSD thumbwheel did not work. 

tracked it to a dead 1820-0732 on the option board.  what is an 1820-0732?  since i don't have a manual for the k20 and can't  find the pin outs for the IC on the interweb.....who the fuck knows what it really is?

did some tracing on the board and snooped around with a scope and decided it is a preset counter (set to be a down counter it turns out....well yeah....that is only logical after you noodle it out).  ordered a down counter and worked up a three IC replacement for the one mystery chip.  (ugly as a dog turd, but it works)

sucess!  here you see it counting a 1 Mhz signal from an 8640b with the gate time set for 456789 uSec.

I can almost smell the dog turd.     J/K....that's a nifty fix. 

And I see you use TinyCAD too. I just knew for some reason I liked you. 

[BU508A]

tracked it to a dead 1820-0732 on the option board.  what is an 1820-0732?  since i don't have a manual for the k20 and can't  find the pin outs for the IC on the interweb.....who the fuck knows what it really is?

I really hate this, when this happens. I did a search in some HP cross references and found this:



The damn thing is sitting on your bench, evil grinning at you but the corresponding place in the list is empty. 

Edit:

added the SN74190N datasheet from TI

The only explanation I have is: probably your IC is a SN74190N with the HP no. 1820-0734, so, some kind of typo in the list.

Edit 2:

Should have checked your schematic more carefully 
74190 doesn't fit. Probably HP has used a 74190 with some additional logic around, similar the way you did.   

[nixiefreqq]

well......except that the hp mystery part has 20 pins, and 74ls190 has 16.

also spent a lot of time trying to find some other hp gear that used an 1820-0732....... with no success.

at least it was possible to figure out some of the pin outs.  but the extra pins that are tied to either +5 or gnd are still unknown.

they might be to configure it as up or down.  or maybe for some other purpose.