Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

I'm not disagreeing with you, but saying that even with Pomona leads (well lets take the leads out of this debate and just focus on the plugs and the sockets that they go into because in my case I have some 12ga cable not the normal 18ga and in anycase YMMV depending where you source your leads from etc., that less of the plug may be in contact than you think.

I have just gone round the various meters etc that I have here and using my digital calipers measured the depth from the face of the meter or the socket (the part of whatever it is that the plastic part of the plug would come to rest on when pushed in as far as it will go) to the point where contact could be first made with the socket tube to make a connection. This distance varies greatly between the meters, from zero on an analogue one through to almost 10mm on the Bryman. The depth to the bottom of the socket tubes seems to in all cases between 19 and 23mm in total.

I find (ignoring analogues) the following results

Meter              Total depth   Recess
Fluke 25              19mm           6.5mm
Fluke 27              19mm           6.5mm
Fluke 8840A         22mm           6.9mm
Fluke 8842A         22mm           6.9mm
HP 3466A            19.5mm         4mm
HP 3468A            19.5mm         6mm
HP 3478A            19.5mm         6mm
Solatron 7045      20.8mm        2.4mm
Metrix MX52        20.6mm        9.2mm
Brymen 867        23.5mm        9.5mm
Robin OM840      21.8mm         7mm
(Metrix 840)

You can work out just how much actual contact length your own plugs would have based on the results above by measuring the length of the contact on the plug from the tip to the plastic body and deduct the figure given for the recess from the above table.

In my case the worst case meter would be the Brymen but that large recess might well be one of the requirements to achieve a CAT4 1000V rating? and the best case would be the Solartron with zero Cat ratings.

Given the range of my plugs spans from 15mm contact length to 22mm then the best "possible" contact length between plug and socket would be Solartron with a 22mm plug giving a whopping 19.5mm of contact length with plug pushed fully in and worst case would the Brymen 867 with the 15mm plug giving a maximum of only 4.5mm contact length with the plug fully pushed in.

In your own individual cases YMMV, but looking at it in that light does make you think a bit more about the humble socket/plug interface relationship thingy.

[med6753]

As promised....

Too short.


Too deep.








You're welcome. 

[Cerebus]

The instinctive mechanical engineer in me is looking at those looong lever arms there and thinking, this is an expensive accident waiting to happen.

[med6753]

The instinctive mechanical engineer in me is looking at those looong lever arms there and thinking, this is an expensive accident waiting to happen.

And the practical technician in me is saying don't be so fucking clumsy. 

[Specmaster]

The instinctive mechanical engineer in me is looking at those looong lever arms there and thinking, this is an expensive accident waiting to happen.

Connection only made because the diameter of the adaptors was small enough to allow the adaptor to be pushed into the recess itself, measure the actual plug contact pins and I think that they would be about the same length. 

[med6753]

As i did when buying a HP boatanchor of a 4 channel SMU and then found 5 Triax connectors on the back and ended up spending more on triax cables than what i bought the boatanchor for.

EDIT: Oh and then bought a different HP SMU and found the triax connectors on that have a different pinout after noticing it was reading garbage with my existing cables.

Yes exactly that. The one that makes me laugh and then cry at the local amateur radio club. It starts with "so I got this HP power meter off ebay - how do I plug my signal into this connector?" followed by "did it come with a power sensor?" followed by "what's one of those?". This is one reason I'm throwing together this power sensor board and an associated tap attenuator combo is so I can say "give me 50 quid to make your problems go away".

I only hope I don't like the 465B too much.

If you get it working, you have no hope.

As bd139 said. If you get it working you won't want to sell it. It just feels and looks right. In many ways I prefer it over my 2465 twins.

[tggzzz]

As i did when buying a HP boatanchor of a 4 channel SMU and then found 5 Triax connectors on the back and ended up spending more on triax cables than what i bought the boatanchor for.

EDIT: Oh and then bought a different HP SMU and found the triax connectors on that have a different pinout after noticing it was reading garbage with my existing cables.

Yes exactly that. The one that makes me laugh and then cry at the local amateur radio club. It starts with "so I got this HP power meter off ebay - how do I plug my signal into this connector?" followed by "did it come with a power sensor?" followed by "what's one of those?". This is one reason I'm throwing together this power sensor board and an associated tap attenuator combo is so I can say "give me 50 quid to make your problems go away".

Quite.

At yesterday's hamfest I actually saw a meter plus power sensor that l suspect worked. My heart skipped a beat, but recovered when he said he wanted £250 for it

I only hope I don't like the 465B too much.

If you get it working, you have no hope.

There's hope. I have a lovely 485

[tggzzz]

I only hope I don't like the 465B too much.

If you get it working, you have no hope.

As bd139 said. If you get it working you won't want to sell it. It just feels and looks right. In many ways I prefer it over my 2465 twins.

I can believe that. Fortunately I have a lovely 485 on my bench. It is difficult to beat the proper 50ohm attenuator in the signal chain - not just a poxy 50ohm resistor slapped across the 20pF input.

[bd139]

That's true. You have a 485. All the other scopes can go home. Apart from perhaps a decent 2465

[nixiefreqq]

ooooooops!    might have wandered into the wrong thread.

[tggzzz]

That's true. You have a 485. All the other scopes can go home. Apart from perhaps a decent 2465

My Digilent Analog Discovery gives a variety of decent <10MHz tools.

If I want 400MHz DSO, I've got a LeCroy 9314(?).

But then why would I want a DSO? The only advantage over an analogue scope for signal integrity is cumulative eyepattens, and I've an 800MS/s logic analyser for digital problems.

[Specmaster]

ooooooops!    might have wandered into the wrong thread.

[bd139]

My Digilent Analog Discovery gives a variety of decent <10MHz tools.

Now there lies an absolute killer tool. Doesn't take up a lot of room, perfect integration with software for signal processing, is a proverbial Swiss army knife anyway. Probably the future.

I'm interesting in knocking up an RF swiss army knife myself of similar proportion and utility. That would be a small VNA really. And you know what, they're not actually that complicated. Looks like you can throw a useful two port analyser up that is good to 2m band with an AD9851, mini circuits directional coupler, AD8302 and an AVR plus some discrete, switching and power conversion bits. BOM, exluding respin fuck ups, is about 80 quid.

[mnementh]

Salvation or double your money back

As I said earlier I’ve spent less on Pomona leads than crap that fell to bits after a week over the years. There is a net saving in buying quality up front.

I dont have a pile of them either. Just what I need and buy when I need them. This totals about 8 banana leads, 3 pairs of clip leads and a couple of BNC/banana/clip adapters. Less than £100.

Have spent more than that this year on just BNC and SO239 connectors.

People seem to forget that a big chunk of cost in EE isn’t the boxes but what you connect them with.

Edit: to note the minigrabbers do need to be replaced regularly in my incompetent hands as I occasionally melt one.

Yeah, but 18ga test leads simply will not do for some of my applications; I run a number of high-current devices on a regular basis. I do a lot of high-current testing. I NEED at least 14-16ga in my test leads; for me it's a minimum requirement. Of course, I like 12ga even better most of the time.

This was exactly my reason for going the route I did when I made my own power/test cables for RC. I couldn't BUY as good as I can MAKE. And if I MAKE, I know EXACTLY how good the solder joints are; I don't have to worry if Xian Hung Lo was good at soldering or a hack, or hungover, or just got dumped and didn't care if the whole world burned, or anything else. I choose what goes into my cables, I know what comes out the other end of the process.

Similar to yours... 10 years later on a pair of 12ga leads I made for ~$8 is hard to beat. All I have to do is be willing to put up with heat shrink instead of fancy molded ends.

My grandfather was a master machinist...

One thing he instilled in me was a deep-rooted understanding of tools and the drive to "Use the right tool for the job. If you can't GET the right tool for the job, MAKE it."

I'm beginning to think that in general, good test leads are one of those tools you just can't get now,  a casualty of the race to the bottom. 

mnem
*Toddles off in search of a Tesla coil to lick*

[tggzzz]

My Digilent Analog Discovery gives a variety of decent <10MHz tools.

Now there lies an absolute killer tool. Doesn't take up a lot of room, perfect integration with software for signal processing, is a proverbial Swiss army knife anyway. Probably the future.

I'm interesting in knocking up an RF swiss army knife myself of similar proportion and utility. That would be a small VNA really. And you know what, they're not actually that complicated. Looks like you can throw a useful two port analyser up that is good to 2m band with an AD9851, mini circuits directional coupler, AD8302 and an AVR plus some discrete, switching and power conversion bits. BOM, exluding respin fuck ups, is about 80 quid.

To merge with the other (DC) thread, the killer is in the cables and connectors (and de-embedding calculations).

If you thought Fischer connectors for Solartron DVMs were expensive, have a look at APC-7 connectors and cables. But I suppose you'll get away with BNC and SMA

[Specmaster]

Salvation or double your money back

As I said earlier I’ve spent less on Pomona leads than crap that fell to bits after a week over the years. There is a net saving in buying quality up front.

I dont have a pile of them either. Just what I need and buy when I need them. This totals about 8 banana leads, 3 pairs of clip leads and a couple of BNC/banana/clip adapters. Less than £100.

Have spent more than that this year on just BNC and SO239 connectors.

People seem to forget that a big chunk of cost in EE isn’t the boxes but what you connect them with.

Edit: to note the minigrabbers do need to be replaced regularly in my incompetent hands as I occasionally melt one.

Yeah, but 18ga test leads simply will not do for some of my applications; I run a number of high-current devices on a regular basis. I do a lot of high-current testing. I NEED at least 14-16ga in my test leads; for me it's a minimum requirement. Of course, I like 12ga even better most of the time.

This was exactly my reason for going the route I did when I made my own power/test cables for RC. I couldn't BUY as good as I can MAKE. And if I MAKE, I know EXACTLY how good the solder joints are; I don't have to worry if Xian Hung Lo was good at soldering or a hack, or hungover, or just got dumped and didn't care if the whole world burned, or anything else. I choose what goes into my cables, I know what comes out the other end of the process.

Similar to yours... 10 years later on a pair of 12ga leads I made for ~$8 is hard to beat. All I have to do is be willing to put up with heat shrink instead of fancy molded ends.

My grandfather was a master machinist... one thing he instilled in me was a deep-rooted understanding of tools and the drive to "Use the right tool for the job. If you can't GET the right tool for the job, MAKE it."

I'm beginning to think that in general, good test leads are one of those tools you just can't get now,  a casualty of the race to the bottom. 

mnem
*Toddles off in search of a Tesla coil to lick*

Yep, for normal test meter leads on bolts and ohms 18ga is perfect but where high current or long leads are required then larger cables are required ideally or at worst allowed for the readings. The other thing bigger cables provide is greater mechanical strength.

[bd139]

My Digilent Analog Discovery gives a variety of decent <10MHz tools.

Now there lies an absolute killer tool. Doesn't take up a lot of room, perfect integration with software for signal processing, is a proverbial Swiss army knife anyway. Probably the future.

I'm interesting in knocking up an RF swiss army knife myself of similar proportion and utility. That would be a small VNA really. And you know what, they're not actually that complicated. Looks like you can throw a useful two port analyser up that is good to 2m band with an AD9851, mini circuits directional coupler, AD8302 and an AVR plus some discrete, switching and power conversion bits. BOM, exluding respin fuck ups, is about 80 quid.

To merge with the other (DC) thread, the killer is in the cables and connectors (and de-embedding calculations).

If you thought Fischer connectors for Solartron DVMs were expensive, have a look at APC-7 connectors and cables. But I suppose you'll get away with BNC and SMA

I know all about APC-7 connectors. I wasn’t allowed near them once

Good connectors are ones that the torque wrench costs a months salary

[mnementh]

As i did when buying a HP boatanchor of a 4 channel SMU and then found 5 Triax connectors on the back and ended up spending more on triax cables than what i bought the boatanchor for.

EDIT: Oh and then bought a different HP SMU and found the triax connectors on that have a different pinout after noticing it was reading garbage with my existing cables.

Yes exactly that. The one that makes me laugh and then cry at the local amateur radio club. It starts with "so I got this HP power meter off ebay - how do I plug my signal into this connector?" followed by "did it come with a power sensor?" followed by "what's one of those?". This is one reason I'm throwing together this power sensor board and an associated tap attenuator combo is so I can say "give me 50 quid to make your problems go away".

I only hope I don't like the 465B too much.

If you get it working, you have no hope.

I'll totes buy one from you. So many HP 436-437-438x power meters I've seen going so cheap...

Speaking of which, there's several "rebuildable" 84xx and 44xx power sensors going for approx half a C right now. Good opportunity for those with the gear to rebuild and recal.

Pretty soon, we're going to end up with a PCA SIG: Patch Cables Anonymous Special Interest Group. Or for those so inclined, Pomona Cables Anonymous.

I’m starting the Church Of Pomona

Hmm, not sure that I like the sound of baptism in DeoxIT.

That sounds like an EXCELLENT name for a micro-distillery...

" De-OX-It Private-label coal-filtered Draco-Vardian Brandy - it'll knock your ox's socks off AND get 'em whiter, or I'll eat your ox!!!"

I'm not seeing a downside here...

mnem
*Rummaging around for copper tubing and tank-making materials*

[Cerebus]

" De-OX-It Private-label coal-filtered Draco-Vardian Brandy - it'll knock your ox's socks off AND get 'em whiter, or I'll eat your ox!!!"

That prompted a loud chuckle here.

BBQ ox anyone? Extra crispy?

[Current project: Too knackered to do any real work so making cider, sage, and onion gravy to go with my sausages this evening.]

[mnementh]

The instinctive mechanical engineer in me is looking at those looong lever arms there and thinking, this is an expensive accident waiting to happen.

And the practical technician in me is saying don't be so fucking clumsy. 

And the wire-a-holic in me is saying "Clumsy has nothing to do with it; gravity will fuxxor those sockets all by itself with that much leverage."

It's also saying "My hand-built 4mm bullet cables will plug right into that, and NOT be a tear-inducing accident waiting for a place to happen."

But I STILL want to be able to incorporate shrouded AND stackable plugs into my test leads... why is that too much to ask?

mnem
*liiiiick-ZZZAP!!!-tingly* Hmmm... *liiiiick-ZZZAP!!!-tingly again* Ooooh... *liiiiick-ZZZAP!!!-liiiiick-ZZZAP!!!-tingly-er* Ohhh, momma...

[mnementh]

" De-OX-It Private-label coal-filtered Draco-Vardian Brandy - it'll knock your ox's socks off AND get 'em whiter, or I'll eat your ox!!!"

That prompted a loud chuckle here.

BBQ ox anyone? Extra crispy?

[Current project: Too knackered to do any real work so making cider, sage, and onion gravy to go with my sausages this evening.]

Proof that derangement runs in packs... breakfast on the griddle: Cajun andouille sausage (sausage made with wine from a local packer just across the Louisianan border) & eggs & fresh-baked biscuits. Yum.

Probably going to have the same thing for lunch, only maybe add some colby-jack cheese and pour it into tacos.

mnem
"Welcome to mnem's Heart-Attack Shack; you kill it, we grill it. Would you like a side of clogged arteries widdat?"

[bd139]

Biscuits are for tea. Heathens! 

Then again you put the tea in the sea!

[mnementh]

Well, in my defense... what you call biscuits we call crackers; this is what we make for breakfast. We accept NO substitutes.

Just like grandmomma used to make... because it IS what she used to make.

She was so pissed off when they released these; she swore they stole her grandmomma's recipe. Then she was like  "Why fight it? Almost as good as mine, a fraction of the work for me."

mnem
*Slurrrp*

[bd139]

That's sort of what I hope will become of my designs. I'm going to publish them free, Chinese will copy them, then I will import the cloned ones and sell them for a markup here thus not having to deal with PCBA and supply chain shite 

[Mr. Scram]

That's sort of what I hope will become of my designs. I'm going to publish them free, Chinese will copy them, then I will import the cloned ones and sell them for a markup here thus not having to deal with PCBA and supply chain shite 

Cool, you're going to be a distributor for the Chinese.