Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 1820483 times)

URI, Cubdriver, exor and 10 Guests are viewing this topic.

Offline Berni

  • Super Contributor
  • ***
  • Posts: 2416
  • Country: si
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15075 on: August 22, 2018, 06:52:35 pm »
Some TEA porn from w2aew...

https://youtu.be/c-y8UmoHbtw

That thing sure beats out my HP one when it comes to the amount of boatanchory, looks like it might be getting towards the two person lift category.
 

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 4888
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15076 on: August 22, 2018, 07:13:31 pm »
Some extra SPECIAL TEA GOODNESS for you all today! Fluke 8200A, tested, guaranteed and warranted for two full years from date of purchase! I bought this meter on ebay and then i dreaded the possibilities, too good to be true, but no it is true! 150 for a working nixie meter that even comes complete with all the options and no stickers barring entry into the device. It came in a radwell international box, obviously since thats the company, double sealed in plastic and then padded, with that expanding foam stuff that conforms to the box, I even got a bag of mints and a power cord. I'd have pictures here but my camera crapped out, maybe later when its warmed up and i have the accuracy results. Whats so good and special you may ask? THEY HAVE MORE https://www.radwell.com/en-US/Buy/FLUKE/FLUKE/8200A , nixie fans rejoice!

Also back to other topics, my table or more specifically it's posts. My dryer crapped out so i had to return it to homeowner hell anyways, while there i checked their inventory of beams, lo and behold! Brand new fresh off the truck just untied 4x6 beams! Straight as an arrow because they didn't even have time to abuse them yet! Sadly since my dryer crapped out again hamfests are going to be a little tight... :palm:

Speaking of hamfest, this friday and saturday i'm going to one, should be fun to see what i drag home. I have a rather fat wad still unaffected by the dryer.

Dryers are easy. More than 50% of DOA failures are caused by garbage buildup that trips a thermal fuse. Disassemble the  lint trap/blower tube, clean the garbage out, find & replace the thermal fuse. If it's not that simple, PM me with symptoms and pics; I may be able to help.



Scoped out Radwell; all I can say is their results for HP were HIGHLY suspect... a Funke Huster Mini Hooter...? a DWYER HP Mag 603...? A US TSUBAKI 7/8 Split Taper...?

Reminds me of when I was little and my grand-dad told me to get him a Glerb-Terwhilliger Pnuder valve with CCW knee action from his machinist' cabinet...


mnem
https://youtu.be/2xLI2J3AopQ
« Last Edit: August 22, 2018, 07:15:24 pm by mnementh »
 

Offline neo

  • Super Contributor
  • ***
  • Posts: 1696
  • Country: us
  • The specialist.
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15077 on: August 22, 2018, 07:40:39 pm »
Dryers are easy. More than 50% of DOA failures are caused by garbage buildup that trips a thermal fuse. Disassemble the  lint trap/blower tube, clean the garbage out, find & replace the thermal fuse. If it's not that simple, PM me with symptoms and pics; I may be able to help.



Scoped out Radwell; all I can say is their results for HP were HIGHLY suspect... a Funke Huster Mini Hooter...? a DWYER HP Mag 603...? A US TSUBAKI 7/8 Split Taper...?

Reminds me of when I was little and my grand-dad told me to get him a Glerb-Terwhilliger Pnuder valve with CCW knee action from his machinist' cabinet...


mnem
https://youtu.be/2xLI2J3AopQ

For the dryer, first let me say the old one is gone and a new one of a different model is in place.
Two months, broken belt... wait a month for a fix then am given the belt and forced to install it myself and then another month it breaks again. In this space of time the wallet bought a dryer that didn't match and so we figured to schlep the crap back to store for a full refund while we still could and replace it with a matching one. So the problem is that GE is now a chinese company.

As for radwell being suspect, well they do SAY they can sell a new 8200A which just reeks of dead fish BUT on the used one i bought they did me right, or so it seems at this point in time.
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 4888
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15078 on: August 22, 2018, 07:58:43 pm »
Let's see if we can figure out what's wrong with the P6430 Temperature Probe that came with the 465B/DM44 purchased last week.

The manual and the probe. The probe body unscrews and the sensor assembly head is an NPN transistor encased in plastic. I found out that it's roughly equivalent to a 2N2484. So let's test the sensor head.
  The test set up:   

The results. It's FUBAR.  :-BROKE It's showing as a diode. Mouser has the 2N2484 in stock and I may order it. As far as getting the original Tek part? Yea.....right. In your dreams.  :o


Are you positive it's not a LM34 or a LM35? That is almost exactly how I'd expect a blown up one to look on the 12864 Whizzbanger.


For the dryer, first let me say the old one is gone and a new one of a different model is in place.
Two months, broken belt... wait a month for a fix then am given the belt and forced to install it myself and then another month it breaks again. In this space of time the wallet bought a dryer that didn't match and so we figured to schlep the crap back to store for a full refund while we still could and replace it with a matching one. So the problem is that GE is now a chinese company.

As for radwell being suspect, well they do SAY they can sell a new 8200A which just reeks of dead fish BUT on the used one i bought they did me right, or so it seems at this point in time.
So... how much for the new 8200A which just reeks of dead fish?  :-DD


mnem
I kill me.
 

Offline neo

  • Super Contributor
  • ***
  • Posts: 1696
  • Country: us
  • The specialist.
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15079 on: August 22, 2018, 08:02:19 pm »
So... how much for the new 8200A which just reeks of dead fish?  :-DD


mnem
I kill me.

330+shipping and tax i think. The meter doesn't reek of dead fish, the fact they can offer a new one does.  :-DD
A hopeless addict (and slave) to TEA and a firm believer that high frequency is little more than modern hoodoo.
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7888
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15080 on: August 22, 2018, 08:24:52 pm »
I think there may already be a supply of suitable feet (& tilt stands) for the full size HP cases out there, it's finding where they get them from that is the problem. Have a look at the Rod-L Electronics webpage and on ebay, do the cases look familiar?

http://www.rodl.com/

The company was started by Roy Clay who had previously worked as the software development manager on the HP 2116A computer.

http://www.rodl.com/management.html

There are a couple of manuals on the web but no mention of any part numbers for the feet. So maybe something else to look out for donor feet if they are cheap, but then again the TEA could kick in & you may end up with a pile of them.  :-DD

I'd never heard of Rod-L Electronics before I found an ebay listing where someone had mentioned the HP looks in the description. Clare stuff seems to be the go-to brand where I work for high voltage insulation testers (now part of Seaward).

Yeah, I saw a couple of those full-rack width enclosures. I think they were Rod-L HIPOT testers and a GPIB interface of some sort. They looked just like old HP. Thanks for the background and confirmation.

Now, if only they used the smaller enclosures, too.
I TEA.
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7888
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15081 on: August 22, 2018, 08:29:11 pm »
Some extra SPECIAL TEA GOODNESS for you all today! Fluke 8200A, tested, guaranteed and warranted for two full years from date of purchase! I bought this meter on ebay and then i dreaded the possibilities, too good to be true, but no it is true! 150 for a working nixie meter that even comes complete with all the options and no stickers barring entry into the device. It came in a radwell international box, obviously since thats the company, double sealed in plastic and then padded, with that expanding foam stuff that conforms to the box, I even got a bag of mints and a power cord. I'd have pictures here but my camera crapped out, maybe later when its warmed up and i have the accuracy results. Whats so good and special you may ask? THEY HAVE MORE https://www.radwell.com/en-US/Buy/FLUKE/FLUKE/8200A , nixie fans rejoice!

Wow, they show that they even have new units (NOS) in addition to two levels of surplus (new/used).

They don't have any 8100A, heh heh. NOS on that would be something.
« Last Edit: August 22, 2018, 08:31:05 pm by bitseeker »
I TEA.
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7424
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15082 on: August 22, 2018, 08:38:19 pm »
So... how much for the new 8200A which just reeks of dead fish?  :-DD


mnem
I kill me.

330+shipping and tax i think. The meter doesn't reek of dead fish, the fact they can offer a new one does.  :-DD
Hmmm...Thought I'd try them out seeing as they have huge place in the UK as well and I looked for a Fluke 8840A and a 8840A/AF which AFAIK are the same basic bench meter, the 8840A is the basic DC only meter and 8840A/AF is the same meter with AC and GPIB modules fitted and they claim to be able to sell me a brand new of each of them but their pricing seems to be a bit suspect to me when they quote on their web site, the 8840A is priced £873.92 and the 8840A/AF is £493.49 + tax. Can anyone explain why the lesser version should be more expensive by £380? :-//
Who let Murphy in?
 

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 4888
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15083 on: August 22, 2018, 09:27:31 pm »
So... how much for the new 8200A which just reeks of dead fish?  :-DD


mnem
I kill me.

330+shipping and tax i think. The meter doesn't reek of dead fish, the fact they can offer a new one does.  :-DD

*rimshot* Bah-Dump-Bump!  ;)

Hmmm...Thought I'd try them out seeing as they have huge place in the UK as well and I looked for a Fluke 8840A and a 8840A/AF which AFAIK are the same basic bench meter, the 8840A is the basic DC only meter and 8840A/AF is the same meter with AC and GPIB modules fitted and they claim to be able to sell me a brand new of each of them but their pricing seems to be a bit suspect to me when they quote on their web site, the 8840A is priced £873.92 and the 8840A/AF is £493.49 + tax. Can anyone explain why the lesser version should be more expensive by £380? :-//

Cost-Plus.

mnem
Seriously.
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7888
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15084 on: August 22, 2018, 09:32:13 pm »
... the 8840A is priced £873.92 and the 8840A/AF is £493.49 + tax. Can anyone explain why the lesser version should be more expensive by £380? :-//

The former is probably "not in stock, so don't ask unless you're ready to pay us to downgrade an 8840A/AF for you" pricing. :-DD
I TEA.
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7424
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15085 on: August 22, 2018, 10:11:10 pm »
Just done a calibration check on my 5.5 digit bench meters after they had been on over 2 hours to get to working temperatures using my AD584-M module and on each of the 4 test voltages they vary by only 0.0001V so I'm extremely happy with my 8840A from Express-Auctions.

Sold as "Parts only - not tested" and needed zero fixing up time to give me a fully functioning meter  :-+
Who let Murphy in?
 

Offline bitseeker

  • Super Contributor
  • ***
  • Posts: 7888
  • Country: us
  • Lots of engineer-tweakable parts inside!
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15086 on: August 22, 2018, 10:12:07 pm »
Suh-weet! :-DMM
I TEA.
 

Offline factory

  • Frequent Contributor
  • **
  • Posts: 267
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15087 on: August 22, 2018, 10:48:18 pm »
I think there may already be a supply of suitable feet (& tilt stands) for the full size HP cases out there, it's finding where they get them from that is the problem. Have a look at the Rod-L Electronics webpage and on ebay, do the cases look familiar?

http://www.rodl.com/

The company was started by Roy Clay who had previously worked as the software development manager on the HP 2116A computer.

http://www.rodl.com/management.html

There are a couple of manuals on the web but no mention of any part numbers for the feet. So maybe something else to look out for donor feet if they are cheap, but then again the TEA could kick in & you may end up with a pile of them.  :-DD

I'd never heard of Rod-L Electronics before I found an ebay listing where someone had mentioned the HP looks in the description. Clare stuff seems to be the go-to brand where I work for high voltage insulation testers (now part of Seaward).

Yeah, I saw a couple of those full-rack width enclosures. I think they were Rod-L HIPOT testers and a GPIB interface of some sort. They looked just like old HP. Thanks for the background and confirmation.

Now, if only they used the smaller enclosures, too.

Unfortunately they only seem to do medium size boat anchors, but it does make me wonder if any other companies are still using ex-HP style cases.
Most of the feet seem to get lost due to being rack mounted, I guess the smaller ones could have been removed from combining cases.

David
« Last Edit: August 22, 2018, 10:49:55 pm by factory »
 

Offline GregDunn

  • Frequent Contributor
  • **
  • Posts: 723
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15088 on: August 22, 2018, 10:53:13 pm »
OK, it looks to be Fluke Week locally.  Coming back from an errand I stopped at a south side pawn shop which I hadn't been to in a while.  Lurking under a stack of otherwise-uninteresting hardware was a Fluke 179.  It was kind of grubby (no physical damage), had no leads or external case, and the numpty who tagged it put the price sticker squarely over the display.   :palm:  Luckily, the associate was friendly and sympathetic, and offered to peel the sticker off since I expressed interest.  It didn't come off very well (he was just using bare fingers, smart enough not to use a questionable utensil) but I could see that all the segments worked and all the inputs gave believable displays.

Oh, the price?  It was marked $110, but (again, sympathetic associate and I didn't badger him) since it had no leads or case and the display was pretty gummy, we quickly reached an agreement on $77.  I think, not too bad!  It seems to work fine on all inputs, though I haven't run it through all the tests yet.

I gently worked on the display with a damp cotton pad and IPA, but it's still quite a bit smeared.  what's the best way to get all the adhesive off without damaging anything?  And similarly, what about the case?  I know these are supposed to be pretty rugged, but no doubt the TEA group has some wisdom to share about cleaning them.  I don't know what solvents might lead to long term damage of the materials.

Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7424
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15089 on: August 22, 2018, 10:55:30 pm »
I think there may already be a supply of suitable feet (& tilt stands) for the full size HP cases out there, it's finding where they get them from that is the problem. Have a look at the Rod-L Electronics webpage and on ebay, do the cases look familiar?

http://www.rodl.com/

The company was started by Roy Clay who had previously worked as the software development manager on the HP 2116A computer.

http://www.rodl.com/management.html

There are a couple of manuals on the web but no mention of any part numbers for the feet. So maybe something else to look out for donor feet if they are cheap, but then again the TEA could kick in & you may end up with a pile of them.  :-DD

I'd never heard of Rod-L Electronics before I found an ebay listing where someone had mentioned the HP looks in the description. Clare stuff seems to be the go-to brand where I work for high voltage insulation testers (now part of Seaward).

Yeah, I saw a couple of those full-rack width enclosures. I think they were Rod-L HIPOT testers and a GPIB interface of some sort. They looked just like old HP. Thanks for the background and confirmation.

Now, if only they used the smaller enclosures, too.

Unfortunately they only seem to do medium size boat anchors, but it does make me wonder if any other companies are still using ex-HP style cases.
Most of the feet seem to get lost due to being rack mounted, I guess the smaller ones could have been removed from combining cases.

David
They also sometimes get removed when people stack them on shelves, this is particularly true if the handle when folded flat, still hits the instrument below if it was in a case that was shaped for example like some the Philips meters etc and subsequently gets lost.
Who let Murphy in?
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7424
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15090 on: August 22, 2018, 11:07:37 pm »
@GreggDunn, thats quite a good snag you got there. To clean the gumminess from the screen you could try Amazon for some "Sticky Stuff Remover" or you could also try a few squirts of WD-40 (not the switch/contact cleaner version but the lubricant) on a cloth and dab that on and let it soak in then wipe it off, this is also very good at cleaning up grubby cases before and have not had any problems with it affecting the cases in any way. If in doubt, try it first of all on the back where it won't be seen to satisfy yourself as to the suitability of it for the job in hand.
Who let Murphy in?
 
The following users thanked this post: GregDunn

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 4888
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15091 on: August 22, 2018, 11:17:30 pm »
OK, it looks to be Fluke Week locally.  Coming back from an errand I stopped at a south side pawn shop which I hadn't been to in a while.  Lurking under a stack of otherwise-uninteresting hardware was a Fluke 179.  It was kind of grubby (no physical damage), had no leads or external case, and the numpty who tagged it put the price sticker squarely over the display.   :palm:  Luckily, the associate was friendly and sympathetic, and offered to peel the sticker off since I expressed interest.  It didn't come off very well (he was just using bare fingers, smart enough not to use a questionable utensil) but I could see that all the segments worked and all the inputs gave believable displays.

Oh, the price?  It was marked $110, but (again, sympathetic associate and I didn't badger him) since it had no leads or case and the display was pretty gummy, we quickly reached an agreement on $77.  I think, not too bad!  It seems to work fine on all inputs, though I haven't run it through all the tests yet.

I gently worked on the display with a damp cotton pad and IPA, but it's still quite a bit smeared.  what's the best way to get all the adhesive off without damaging anything?  And similarly, what about the case?  I know these are supposed to be pretty rugged, but no doubt the TEA group has some wisdom to share about cleaning them.  I don't know what solvents might lead to long term damage of the materials.

Also - they had a 73 III which actually looked to be physically in better condition but when powered up about half of the LCD segments flickered; there was no battery indication that I could see.  I passed.  It was $35, but not knowing whether the problem was minor or major I thought it was a risky move.  Good call?



Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.


mnem
goo.
« Last Edit: August 22, 2018, 11:20:21 pm by mnementh »
 
The following users thanked this post: GregDunn

Offline factory

  • Frequent Contributor
  • **
  • Posts: 267
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15092 on: August 22, 2018, 11:37:30 pm »
Some TEA porn from w2aew...

https://youtu.be/c-y8UmoHbtw

That thing sure beats out my HP one when it comes to the amount of boatanchory, looks like it might be getting towards the two person lift category.

Very nice, I guess not very common & probably well over my TEA budget, so I'll have to stick with my cheaper & slightly dis-functional Heathkit Griefkit curve tracer + whatever boatanchor scope I decide to use. I did try testing a tunnel diode with it, but didn't get round to finding out which wasn't working.

David

edit: More on the Heathkit IT-1121 curve tracer here;
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1776971/#msg1776971
« Last Edit: August 26, 2018, 11:52:41 pm by factory »
 

Online tautech

  • Super Contributor
  • ***
  • Posts: 16010
  • Country: nz
  • Taupaki Technologies Ltd. NZ Siglent Distributor
    • Taupaki Technologies Ltd.
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15093 on: August 22, 2018, 11:40:48 pm »
slightly dis-functional Heathkit Griefkit curve tracer
:-DD
New one for the POI's, bitseeker.

.....................
Chuckling.
« Last Edit: August 22, 2018, 11:51:11 pm by tautech »
Avid Rabid Hobbyist
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 7424
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15094 on: August 22, 2018, 11:46:32 pm »
Well that Heathkit Griefkit curve tracer certainly seems to be working just fine  :-+
Who let Murphy in?
 

Offline GregDunn

  • Frequent Contributor
  • **
  • Posts: 723
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15095 on: August 22, 2018, 11:49:57 pm »
@mnementh, Specmaster, thanks - that's what I was looking for.  Windex (not the ammonia-laden version) has always been a go-to for mild cleanup, but I'll check locally for Goo Gone or its generic equivalent right away before I do my next Amazon order.
 

Offline Cerebus

  • Super Contributor
  • ***
  • Posts: 3396
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15096 on: August 22, 2018, 11:56:52 pm »
Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Citrus oil is principally limonene and I know from experience that limonene is a highly effective dissolver of polystyrene, acrylic and ABS so caution is needed. Brief application may dissolve label adhesive before it dissolves the plastic underneath the label but please, please, don't leave difficult labels soaking in the stuff on plastic surfaces or you may well return to a gooey mess. A cautious approach is strongly advised.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.

Be careful of any solvent on polycarbonate, it's very prone to a phenomenon known as solvent crazing, which is a close relative of of stress corrosion cracking. Be especially careful near any polycarbonate that's used for safety purposes (guards, helmets, anti-projectile barriers) as solvent crazing can make it fail spectacularly in stress without being obviously apparent beforehand.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 
The following users thanked this post: GregDunn

Offline factory

  • Frequent Contributor
  • **
  • Posts: 267
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15097 on: August 22, 2018, 11:59:31 pm »
slightly dis-functional Heathkit Griefkit curve tracer
:-DD
New one for the POI's, bitseeker.

.....................
Chuckling.

Well that Heathkit Griefkit curve tracer certainly seems to be working just fine  :-+

I'm sure someone else on here called them that, so went along with it, I think it had something to do with the original owners assembling the kits wrong. I must dig it out and see if I can get it to work with any tunnel diodes, I suspect I have a dead one in the HP 5248M, may have to buy some Russian ones if I can figure out the correct type to order.

David
 

Offline nixiefreqq

  • Frequent Contributor
  • **
  • Posts: 384
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15098 on: August 23, 2018, 12:31:59 am »
wow.  that guy jim Williams was right.

you really can make a sub nanosecond pulse generator with parts from the junk box.

transistor - 2n3904
bias resistor - 1 Megohm
relaxation cap - 3 ea 12 pf 50 V in series
avalanche voltage - 120-135V

how much narrower is the pulse than the 870ps shown?  impossible to know with a 400 Mhz scope. (but this sure is one of those applications where equivalent time sampling works great)

ok ok.  should have used a real power supply instead of the leakage test voltage from an antique cap/res bridge. 

but it was close to hand.  and i like tuning eyes.


"free range primate"
 
The following users thanked this post: SeanB

Offline GregDunn

  • Frequent Contributor
  • **
  • Posts: 723
  • Country: us
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #15099 on: August 23, 2018, 01:02:15 am »
Goo Gone. Then wipe it all down with a cloth soaked in Windex to get the last bits of of the Goo Gone oil. Goo Gone used to be mostly citrus oil, but the last few years it's clearly being augmented with some petroleum distillates; however still my solvent of choice for adhesive on plastic. No evidence that it isn't just as safe on plastic as it's always been, but it is now a bit petroleum stinky. I just tried some on the lens on my 189; yup, safe as ever.

Citrus oil is principally limonene and I know from experience that limonene is a highly effective dissolver of polystyrene, acrylic and ABS so caution is needed. Brief application may dissolve label adhesive before it dissolves the plastic underneath the label but please, please, don't leave difficult labels soaking in the stuff on plastic surfaces or you may well return to a gooey mess. A cautious approach is strongly advised.

Be careful with IPA; it can cause some plastics (like polycarbonate as used on Fluke meters) to go cloudy, especially with age.

Be careful of any solvent on polycarbonate, it's very prone to a phenomenon known as solvent crazing, which is a close relative of of stress corrosion cracking. Be especially careful near any polycarbonate that's used for safety purposes (guards, helmets, anti-projectile barriers) as solvent crazing can make it fail spectacularly in stress without being obviously apparent beforehand.

Not going to leave it sit on the display; in fact, I'll probably use some cleaner/polish specifically intended for plastics after I get all the gunk off.  I suspect the integral holster is not as big a deal, though it will be cleaned again following the Goo Gone, just to get the smell off.   ;D
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf