Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 2866405 times)

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Online Berni

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19275 on: November 07, 2018, 12:48:40 pm »
As he describes it it seams that a resistive impedance converter was used by HP to make it 75 Ohm and he just removed it. For 1.5 GHz you could probably DIY one even out of SMD resistor and have it be nice and flat.

I find it quite neat how every setting is a knob. Just dial in your span and RBW and reference level like a big ol timebase knob on a scope. Even old spectrum analyzers quickly stopped having big clunking knobs.
 

Offline xrunner

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19276 on: November 07, 2018, 12:59:10 pm »
Haha yea I was referring to the "IMPUT" not sure what that is LOL.

Oh but look at the CAL Output BNC - the center pin seems to be sticking way out without the plastic ferrule around it. Doesn't that look odd?
I am a Test Equipment Addict (TEA) - by virtue of this forum signature, I have now faced my addiction
 
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Offline scl

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19277 on: November 07, 2018, 02:21:11 pm »

I think the CAL Output connector is a normal 75 Ohm BNC.
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19278 on: November 07, 2018, 03:16:38 pm »
Fuck... first bite of breakfast, and a spot of egg yolk on my keyboard. Put my plate down to clean it up real quick, and knock eggy fork off onto the floor.    :palm:

I can see what kind of day this is shaping up to be already; I'm going back to bed.

mnem
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19279 on: November 07, 2018, 03:26:09 pm »
My youngest poured 1kg of glitter in the carpet this morning. Swap?  :-DD
 

Online tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19280 on: November 07, 2018, 04:22:17 pm »
My youngest poured 1kg of glitter in the carpet this morning. Swap?  :-DD

With Dyson vacuum cleaners they can (be forced to) see it disappearing, never to be returned. That might stick in their mind :)
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19281 on: November 07, 2018, 04:36:10 pm »
Unfortunately my DC07 snuffed it about 2 years ago otherwise I would have done exactly that. Henry does a good job though





Edit to keep it TEA related. I need a decade box. Thinking about grabbing one of these from CPC as it's relatively cheap, has a decent range unlike some of the other ones and looks like it might be easy enough to repair when I inevitably smoke it.

https://cpc.farnell.com/tenma/72-7270/resistance-decade-box/dp/IN04175

Any thoughts?

Use cases are mainly small signal impedance measurement, tuning opamp circuits, measurement bridges.

I can't be arsed to build one before anyone suggests that :)
« Last Edit: November 07, 2018, 04:42:32 pm by bd139 »
 

Online tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19282 on: November 07, 2018, 05:36:28 pm »
Edit to keep it TEA related. I need a decade box. Thinking about grabbing one of these from CPC as it's relatively cheap, has a decent range unlike some of the other ones and looks like it might be easy enough to repair when I inevitably smoke it.
https://cpc.farnell.com/tenma/72-7270/resistance-decade-box/dp/IN04175

Any thoughts?

Use cases are mainly small signal impedance measurement, tuning opamp circuits, measurement bridges.

I can't be arsed to build one before anyone suggests that :)

I've never seen the point in them, doubly so when considering their fragility when you change 1001 to 999 "the wrong way".
Long leads are a problem in many circuits; interference , inductance.
Adding a 1ohm resistor to a 1kohm resistor doesn't result in a 1.001kohm resistor[1].
For opamp circuits, first calculate, then build manhattan, then add/subtract resistors on judiciously placed pads.

OTOH, one type of "bridge" is invaluable and difficult to replace: a KVD. Especially if it is a 7decade device, which also gets you bragging rights, e.g.
https://www.eevblog.com/forum/metrology/teardownjulie_reasearch_labs_vdr1067_vdr307_kelvin_varley_voltage_divider/msg1103686/#msg1103686

[1] exception: precision devices such as 121.1ohm (+20mohm!) Dekastats:


There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19283 on: November 07, 2018, 05:48:12 pm »
Certainly don’t need anything that nice of accurate or down to that resolution. 1% over the range is fine.

Have been using that approach so far. I would like however to be able to change some circuit parameters a little easier. I usually solder a trimmer in (I got a bourns trimmer dev kit ages ago), do the measurement, desolder it and measure with DMM. It’s just inconvenient.
 

Offline 0culus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19284 on: November 07, 2018, 05:52:06 pm »
Received my second P6201 FET probe. It appears to be practically brand new with all accessories present (unlike the Boeing one above)! The ground clip and accessories are sealed in a bag and it has a Tektronix inspection tag tied to the leads. Now to wait on the Tek 1101 accessory power supply I got.
 

Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19285 on: November 07, 2018, 06:00:50 pm »
Certainly don’t need anything that nice of accurate or down to that resolution. 1% over the range is fine.

Yes, but that CPC decade box is 5%, building one is a piece of piss after the thing you've been building lately, once you have the parts its about an hours work and its done.  :-+
Who let Murphy in?

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Online tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19286 on: November 07, 2018, 06:06:05 pm »
Certainly don’t need anything that nice of accurate or down to that resolution. 1% over the range is fine.

Have been using that approach so far. I would like however to be able to change some circuit parameters a little easier. I usually solder a trimmer in (I got a bourns trimmer dev kit ages ago), do the measurement, desolder it and measure with DMM. It’s just inconvenient.

Trimmer is perfectly respectable, of course.

I suppose I associate resistance boxes with solderless breadboards, and I hate the latter with a vengence! I believe I would come to hate the former, if I ever used them.

Of course I don't need the KVD and Dekastat - but you should be expunged from this thread for even raising that concept!

I've just thought of a use for a resistance box: to sell at a hamfest. Second hand ones are ideal, since they are cheap and an impulse purchase: everybody thinks "oooh, I'm sure one of those will com in handy".
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19287 on: November 07, 2018, 06:52:51 pm »
Fuck... first bite of breakfast, and a spot of egg yolk on my keyboard. Put my plate down to clean it up real quick, and knock eggy fork off onto the floor.    :palm:

I can see what kind of day this is shaping up to be already; I'm going back to bed.

mnem
Verticalness is highly overrated.
My youngest poured 1kg of glitter in the carpet this morning. Swap?  :-DD
In a heartbeat. THAT has epic comedic value; you'll be telling that story to embarrass them in front of their prom dates.   >:D

My oldest wet the bed this morning. AGAIN. Trade? :-DD

mnem
And yet, I STILL put both feet on the ground every morning.
 

Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19288 on: November 07, 2018, 06:56:11 pm »
I need a decade box. Thinking about grabbing one of these from CPC as it's relatively cheap, has a decent range unlike some of the other ones and looks like it might be easy enough to repair when I inevitably smoke it.

https://cpc.farnell.com/tenma/72-7270/resistance-decade-box/dp/IN04175

Any thoughts?

Use cases are mainly small signal impedance measurement, tuning opamp circuits, measurement bridges.

I can't be arsed to build one before anyone suggests that :)

I fixed and use a couple of old IET RCS-500 boxes (R: 7 decades, 1Ω resolution, 1%; C: 6 decades, 100pF resolution, 4%). They use thumb wheel switches, which are still working OK, but of course don't compare to the big self-cleaning switches in the old GenRad 1432/1433 or similar.
I TEA.
 

Online Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19289 on: November 07, 2018, 10:03:12 pm »
My youngest poured 1kg of glitter in the carpet this morning. Swap?  :-DD

The only people I know who buy glitter by the kilogram are infant school art teachers and drag queens. We know you aren't an infant school art teacher. Is there something you need to tell us?
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline Housedad

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19290 on: November 07, 2018, 10:24:27 pm »
Henry the Hoover!!!

Laughed my butt off!!
At least I'm still older than my test equipment
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19291 on: November 07, 2018, 10:33:55 pm »
The only people I know who buy glitter by the kilogram are infant school art teachers and drag queens. We know you aren't an infant school art teacher. Is there something you need to tell us?

Inlaws that hate me is the secret here :)

Still no resistance substitution box solution yet. I am now considering building my own but as usual the problem is with finishing off the unit i.e. knobs/legends etc. Turns out that knobs with 0-9 skirts are bloody expensive.
 

Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19292 on: November 07, 2018, 10:38:20 pm »
The only people I know who buy glitter by the kilogram are infant school art teachers and drag queens. We know you aren't an infant school art teacher. Is there something you need to tell us?

Inlaws that hate me is the secret here :)

Still no resistance substitution box solution yet. I am now considering building my own but as usual the problem is with finishing off the unit i.e. knobs/legends etc. Turns out that knobs with 0-9 skirts are bloody expensive.
You could use thumbwheel switches, much cheaper and also smaller and you can even use your beloved SMD resistors soldered directly onto each switch?

Heres one I made last year using TH 1% resistors .25w rated IIRC. It can in theory provide 9,999,999 ohms +/- 1% but you can take higher if required as the switches come in groups of 10

« Last Edit: November 07, 2018, 11:09:49 pm by Specmaster »
Who let Murphy in?

Brymen-Fluke-Solartron-HP-Thurlby-Heathkit-Thander-Tek-Extech-Black Star-GW-Advance-Avo
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19293 on: November 07, 2018, 10:56:48 pm »
Possibility. That is up for consideration. Finding some reliable thumbwheel switches isn't as easy as it looks sometimes though :D
 

Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19294 on: November 07, 2018, 11:05:10 pm »
Depends on just how much you will be using it and also the power you intend to pump through, I used some cheap ones of ebay, 1% resistors rated at either .25 or .5W IIRC. Obviously they are not that accurate at very low ohms due to contact resistance but it gets remarkably accurate the higher up the scale you go.

It reads about 2 ohms higher throughout and unless you really need to be that precise at the low end it is fine.
Who let Murphy in?

Brymen-Fluke-Solartron-HP-Thurlby-Heathkit-Thander-Tek-Extech-Black Star-GW-Advance-Avo
 

Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19295 on: November 07, 2018, 11:30:22 pm »


SO feeling this today.

mnem
Did I mention that I'm self-employed?
 

Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19296 on: November 08, 2018, 12:10:01 am »
err let me think about for a minute.....YES  :-DD :-DD :-DD
Who let Murphy in?

Brymen-Fluke-Solartron-HP-Thurlby-Heathkit-Thander-Tek-Extech-Black Star-GW-Advance-Avo
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19297 on: November 08, 2018, 12:17:57 am »
Depends on just how much you will be using it and also the power you intend to pump through, I used some cheap ones of ebay, 1% resistors rated at either .25 or .5W IIRC. Obviously they are not that accurate at very low ohms due to contact resistance but it gets remarkably accurate the higher up the scale you go.

It reads about 2 ohms higher throughout and unless you really need to be that precise at the low end it is fine.

Usual range is around 200R - 5M or so. Nothing more either way. Accuracy isn't a big deal at low end. Not a lot of power either. Most of the time it'll be used to find a close resistor substitution within a few percent.

I may build one. I have found some reasonable switches (low contact resistance MBB) and some knobs now. Looking to cost about the same as a Tenma one though...

Anyway I stayed up late so I could escalate my Fluke 87IV claim (bastard!) so I'm going to bed now.

Edit: well that was quick. Refunded already due to no tracking provided. Well done eBay.
« Last Edit: November 08, 2018, 12:38:51 am by bd139 »
 

Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19298 on: November 08, 2018, 02:37:31 am »
Anyway I stayed up late so I could escalate my Fluke 87IV claim (bastard!) so I'm going to bed now.

Edit: well that was quick. Refunded already due to no tracking provided. Well done eBay.

And then it shows up tomorrow. :-DD
I TEA.
 

Offline Carl_Smith

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #19299 on: November 08, 2018, 03:02:45 am »
So I reviewed the list of abbreviations in the first message of this thread and I can't find one that applies to my situation.

The situation where you know you have a piece of test equipment but you can't find it.  You've looked everywhere, you know you have it, you know it exists somewhere within a finite distance of where you are now, but you can't figure out where the dang thing is.

Specifically, after giving up on repairing my first multimeter, the little pocket meter that I said would work only when I pushed hard on the case in one spot, I decided to move on to fixing my second meter.  A vintage Radio Shack meter.  I quit using it many years ago when it started doing strange things on some functions.  Don't remember the details over 20 years later.  I used it's malfunction as an excuse to get a better meter.   But now I'm curious if I can repar it, and it's no where to be found...

Edit:  Update - As soon as I post this, a thought occurs to me, "I know one more place where it might be."  I found it in a box of stuff in the hall closet.  Where coats and shoes and stuff go.  Not test equipment....   The problem is that a couple decades of storage in it's retail box, in a moving box full of other junk, it hasn't fared well.  Pictures and more story may be forthcoming, but I have to go cram the rest of the junk back into the closet.
« Last Edit: November 08, 2018, 04:23:23 am by Carl_Smith »
 


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