Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Similarly I've gone the other way. 144MHz from 12MHz with 4 transistors ... oscillator + x3 x2 x2

It's more fun!

[tggzzz]

Similarly I've gone the other way. 144MHz from 12MHz with 4 transistors ... oscillator + x3 x2 x2

It's more fun!

That Tek instrument also goes from 10MHz to 500MHz, using minature valves (nuvistors) and some interestingly shaped bits of metal - as I posted earlier.

[mnementh]

      I thought I would show my rough dc loads, used to proof test a 28V 35A linear PSU, it powered my 1.2GHz 350W PA for EME.

I didn't run them for too long as everything gets very hot esp me! So close to b-f design but mine are much rougher I am afraid.

 
ROUGH...?!? I'll show you ROUGH. But remember, ya MADE ME!!! 

                        

And for those who can't live without actual specs; since now I actually have a tool that will tell me:

Elements are 4 ea of : 1.8mm dia. steel wire wrapped around a 12mm deep socket as a former. Finished 18 turns, ~16mmID/20mmOD, approx 4.5mm spacing between turns. All measurements taken at 20.1°C Ambient. Fresh, cold tap water in bowl, as this is what is used for PSU testing.

1-DC Resistance Dry: 0.27Ω

2-ESR Dry @ 1KHz: 0.281Ω

3-Inductance Dry @ 1KHz: 22.7uH / Q=0.505

4-Capacitance Dry @ 1KHz: 1107uF / tan δ(D)=1.948

5-DC Resistance Wet: 0.24Ω

6-ESR Wet @ 1KHz: 0.259Ω

7-Inductance Wet @ 1KHz: 23.2uH / Q=0.561

8-Capacitance Wet @ 1KHz: 1091uF / tan δ(D)=1.781

Okay... so now you have some baseline specs on my "Coiled Coathanger Ballast Resistor"; you can actually make use of it if you desire. These figures coincide pretty well with the calculated value of 0.304Ω from the demonstration photo above. 

I've confirmed in use that bypassing individual elements results in linear current increase, so each element will be 1/4 of these values. 

mnem
"Nothing succeeds like excess." ~me

[worsthorse]

Been playing with 10MHz OCXO's and wanted another dedicated power supply I could run for some long term testing.  Found what looked to be a clean, late version HP 6227B (0-25v, 0-2A, dual channel) on eBay not to far from me.  This was the only test equipment item in the sellers store, so I made an offer for $75 from the $135 asking and they accepted.  Shipped fast, and very well packaged which was a pleasant surprise.  Its in better shape than I had hopped for, appears 100% original and no signs of any work.  I am seeing some ripple at max load, more so from the main channel.  The main filter bank caps do appear week, and C10 on the master regulator board needs to be replaced, but this is to be expected.  The hunt is on for some caps, but well worth it for such a nice peace of gear, they don't make things like they use to.

nice bit of kit and very nice photos. Thanks for posting!

I think that's because most of the early digital storage ones were crap! Case in point, this horrid thing which passed through my hands very quickly:

Yes indeed. Stunning ADC (and DAC) improvements have been made since the early/mid 90s. That was one of the disappointingly few major differences when I returned to electronics a few years ago. (Nanopower is the other).

At the same time it has led to "commidity integration" where every device is the same digital ARM black blob with some light weight analogue interfaces around the edge. As always I'm too late to the party to enjoy the good bits.

i returned to building electronics after a thirty-five year break.  i haven’t been that far away that the black blob phenomena was a surprise; i just wasn’t interested in hanging in that playground.  my solution was to assemble a state of the art lab, circa 1984, and to build stuff from books like solid state design for the radio amateur . the last couple of years has been as much about finding gear and parts, and rehabbing gear as about building circuits.  it continues to be an awful lot of fun, especially when i get some old piece of test gear running like it did the first time i encountered it in 1980.  and i hang out here because i like knowing there are folks that enjoy this stuff as much as i do.

[bd139]

You're certainly in good company. On the bench... 



I was building filters earlier and it covers those nicely.

[0culus]

You're certainly in good company. On the bench... 

I approve of the shameless RPN plug. 

[bd139]

Wasn't intentional but the equals button fanboys can take your button and stick it where the sun doesn't shine 

[Specmaster]

Tubes are quite easy to blow up from experience, at least when in my hands 

Yep they sure are if you drop them[emoji1787]

[mnementh]

Been playing with 10MHz OCXO's and wanted another dedicated power supply I could run for some long term testing.  Found what looked to be a clean, late version HP 6227B (0-25v, 0-2A, dual channel) on eBay not to far from me.  This was the only test equipment item in the sellers store, so I made an offer for $75 from the $135 asking and they accepted.  Shipped fast, and very well packaged which was a pleasant surprise.  Its in better shape than I had hoped for, appears 100% original and no signs of any work.  I am seeing some ripple at max load, more so from the main channel.  The main filter bank caps do appear week, and C10 on the master regulator board needs to be replaced, but this is to be expected.  The hunt is on for some caps, but well worth it for such a nice piece of gear, they don't make things like they use to.

         

   

Before you go writing off any of those caps, I'd physically remove them and confirm it's not just crusty pads/posts on the caps. I can't count the number of such PSUs I've restored to former glory with just a little patience and a $2 pack of detail brushes from Horror Fraught. Fiberglas pen scrubbers are magical on tinned traces.

Of course if you're aware of all this, just chalk it up to advising the next guy who comes along who might not be. 

Cheers,

mnem
*Lunch-ily*

[med6753]

You're certainly in good company. On the bench... 



I was building filters earlier and it covers those nicely.

Are you sure that doesn't say "How NOT to blow shit up"? 

[mnementh]

You're certainly in good company. On the bench...        I was building filters earlier and it covers those nicely.

Are you sure that doesn't say "How NOT to blow shit up"? 

He's still working on the code for that feature set.

mnem
"Start with fire; work your way back from there."

[Specmaster]

   2430 Digital (Top) vs 2465 Analog (Bottom). Both in the 1986 Tek catalog. 2430 b/w 150MHz. 2465 b/w 300MHz. One must have really wanted a DSO in 1986. Why? 2430 cost $8900 USD. 2465 cost $5350 USD. Quite a difference. 

Well yeah... the ability to capture nonrepetitive events was a game-changer back then; one of the Holy Grails of scope design. Along with ever-shorter risetimes, which was one of the 24xx series strong points. 

Looks beautiful to me... empirical proof that DSO and CRO can not only peacefully coexist, but will in many cases happily cohabitate as well. 

mnem
"No electron gun, no sale." ~ old man Kirsch

And even in the same case as well as demonstrated by my combiscope, not only that, but the combiscope even cohabitates with my DSO (TDS210) which is a feat that my cats can't do and they are sisters FFS, if they get too close there is a lot of hissing and paw waving going on 

[med6753]

   2430 Digital (Top) vs 2465 Analog (Bottom). Both in the 1986 Tek catalog. 2430 b/w 150MHz. 2465 b/w 300MHz. One must have really wanted a DSO in 1986. Why? 2430 cost $8900 USD. 2465 cost $5350 USD. Quite a difference. 

Well yeah... the ability to capture nonrepetitive events was a game-changer back then; one of the Holy Grails of scope design. Along with ever-shorter risetimes, which was one of the 24xx series strong points. 

Looks beautiful to me... empirical proof that DSO and CRO can not only peacefully coexist, but will in many cases happily cohabitate as well. 

mnem
"No electron gun, no sale." ~ old man Kirsch

And even in the same case as well as demonstrated by my combiscope, not only that, but the combiscope even cohabitates with my DSO (TDS210) which is a feat that my cats can't do and they are sisters FFS, if they get too close there is a lot of hissing and paw waving going on 

Actually the case on the 2430 is about 2 inches longer in back than the 2465.

[med6753]

Look at this. Bastard tant! The 47uf tant on the primary input to the HV oscillator. Shorted and took out the fuse. Always change this cap! 

Then he opens up an older 465 and it shows the 2 - 22uf tants in parallel. Get rid of them too.

[bd139]

Yeah that cap is why I usually buy the ones with failed HT. it’s 99% likely to be that and takes about two minutes to fix. I actually gave fuses in stock in case another scope comes along 

[0culus]

   2430 Digital (Top) vs 2465 Analog (Bottom). Both in the 1986 Tek catalog. 2430 b/w 150MHz. 2465 b/w 300MHz. One must have really wanted a DSO in 1986. Why? 2430 cost $8900 USD. 2465 cost $5350 USD. Quite a difference. 

Well yeah... the ability to capture nonrepetitive events was a game-changer back then; one of the Holy Grails of scope design. Along with ever-shorter risetimes, which was one of the 24xx series strong points. 

Looks beautiful to me... empirical proof that DSO and CRO can not only peacefully coexist, but will in many cases happily cohabitate as well. 

mnem
"No electron gun, no sale." ~ old man Kirsch

And even in the same case as well as demonstrated by my combiscope, not only that, but the combiscope even cohabitates with my DSO (TDS210) which is a feat that my cats can't do and they are sisters FFS, if they get too close there is a lot of hissing and paw waving going on 

Actually the case on the 2430 is about 2 inches longer in back than the 2465.

Interesting. It's a nice looking scope, maybe primitive compared to later DSOs, but at least it only has soft keys rather than full fledge menus!

[PA0PBZ]

Found what looked to be a clean, late version HP 6227B

Is that cap really saying 80uF, 0-65VDC?   

[kj7e]

Before you go writing off any of those caps, I'd physically remove them and confirm it's not just crusty pads/posts on the caps. I can't count the number of such PSUs I've restored to former glory with just a little patience and a $2 pack of detail brushes from Horror Fraught. Fiberglas pen scrubbers are magical on tinned traces.

Of course if you're aware of all this, just chalk it up to advising the next guy who comes along who might not be. 

Cheers,

mnem
*Lunch-ily*

Before I powered it up, I had removed the caps to inspect/clean and run up the voltage on them slowly.  They are weak, but I found some nice replacements from Mouser for about $11/pop and in-stock.

[kj7e]

Found what looked to be a clean, late version HP 6227B

Is that cap really saying 80uF, 0-65VDC?   

Yeah, and that's C10 on the master reference board.  Its a common part on these supply's that needs to be replaced.  I think I will replace it with a fixed working voltage part though 

[mnementh]

Found what looked to be a clean, late version HP 6227B

Is that cap really saying 80uF, 0-65VDC?      

Yup; was a Sprague nomenclature "thing" back in the day. Took oodles of those out of my 2230. It always made me chuckle. 

mnem
*p00t!*

[Specmaster]

Look at this. Bastard tant! The 47uf tant on the primary input to the HV oscillator. Shorted and took out the fuse. Always change this cap! 

Then he opens up an older 465 and it shows the 2 - 22uf tants in parallel. Get rid of them too.

Wow, that scope is well travelled, all the way from my old stomping ground, BBC TV Centre, Wood Lane, London W12, that place was swimming with Tek scopes. I really should have got one from them at the time when they switched over to digital ones but I was in my hiatus with electronics then due to having a very young family and sod all money to  spare 

[mnementh]

Found what looked to be a clean, late version HP 6227B

Is that cap really saying 80uF, 0-65VDC?      

Yeah, and that's C10 on the master reference board.  Its a common part on these supply's that needs to be replaced.  I think I will replace it with a fixed working voltage part though 

Yeah, and don't forget its brother and cousins on the same board. 
I've come to hold a healthy loathing for large-value axial caps over the last few years; cost on them is ducking insane, IF you can find something even reasonably close to substitute.

mnem
*Breathe... just breathe...*

[med6753]

Found what looked to be a clean, late version HP 6227B

Is that cap really saying 80uF, 0-65VDC?      

Yeah, and that's C10 on the master reference board.  Its a common part on these supply's that needs to be replaced.  I think I will replace it with a fixed working voltage part though 

Yeah, and don't forget its brother and cousins on the same board. 
I've grown a healthy loathing for large-value axial caps over the last few years; cost on them is ducking insane, IF you can find something even reasonably close to substitute.

mnem
*Breathe... just breathe...*

If there's enough headroom I will substitute a radial cap and put shrink tubing on the leads. Done that on several of my Fluke DMM's.

[tautech]

Before you go writing off any of those caps, I'd physically remove them and confirm it's not just crusty pads/posts on the caps. I can't count the number of such PSUs I've restored to former glory with just a little patience and a $2 pack of detail brushes from Horror Fraught. Fiberglas pen scrubbers are magical on tinned traces.

Of course if you're aware of all this, just chalk it up to advising the next guy who comes along who might not be. 

Cheers,

mnem
*Lunch-ily*

Before I powered it up, I had removed the caps to inspect/clean and run up the voltage on them slowly.  They are weak, but I found some nice replacements from Mouser for about $11/pop and in-stock.

Did you try Tedds ?
https://www.tedss.com/Capacitors/Browse/aluminum-electrolytic-large-can-computer-grade

[bd139]

Quick ethical question here. Is it morally acceptable to eviscerate a piece of HP gear which is entirely not useful for the knob caps for my 6236B, guts and the extremely nice case it comes in which will be reused for a project? HP 3551A is the device in question.