Test Equipment Anonymous (TEA) group therapy thread

[tautech]

The heathkit HT supply is a notable bit of kit too. Good second hand market value 

Yeah, HT supplies are hard to come by. For some reason. I'm looking for a 6209, of course.

And it seems with the steady decrease in operating voltages for microprocessors that a lot of people will soon be thinking anything over fifteen volts is high voltage!

-Pat

ISTR an old video where Dave said he is scared with anything above 12Volts... since the day as a kid he got zapped while fiddling inside his parents television...

Getting a mains voltage shock off an old electric bar fire was what got me interested in electronics! I was about seven at the time...

Villiers Mk10 ignition system shock did it for me ! 

[Zenith]

According to the manual, the OXCO option uses the same socket as the regular oscillator & TXCO option, all the extra PSU parts are already fitted right next to the socket, just need two #6x32 3/8 inch screws & fiber washers, might be a link that needs removing too (shown on the diagram).

The counter, buffer/storage & display decoder ICs use negative logic, this is opposite to more common 7490, 7475 & 74141 parts, also pinouts are different, the HP custom ICs can also blank unused readout choobs and the custom buffer/storage IC has extra outputs for the recorder/printer output, this probably won't matter if you haven't got a recorder (I have a 5055A in the repair queue).

All the information is in the free pdf 5326B manual (254MB) that is on the web somewhere, it might be possible to use regular ICs to achieve the same function, but more ICs would be needed, surface mount parts would help fit it in the available space.
Alternately keep an eye out for sellers flogging HP N***e choobs & ask if they will sell the board that they stole them from and hope they still work, parts are 1820-0092, 1820-0116 & 1820-0119.

Have you tried repairing the fan? It could have worn spacers and/or need oiling.

David

I'm sure I looked up the manual on the web when I got it. It may even have come with a manual - I'll have to look. I had the covers off and gave it a look over after I bought it.

I thought that if I wanted to put an OCXO in this, it would be easier and better to get a modern used one from China and make up a board for it, rather than track down the proper HP unit.

I hadn't investigated the three chips in any detail, it was just a thought that it might be possible to achieve their function with a board using modern components. I certainly haven't tried tracking down the Nixie tubes on ebay etc. If I came across another 5326B or similar, at pocket money prices, I'd buy it even in a tatty state.

I did oil the fan but I didn't investigate the spacers. I assumed the racket was down to the bearings being knackered.

[Cerebus]

Hey I’ve earned tenure now 

As for the duff probe, dodgy from the start. The guy at Telonic said they’d had quite a few duff ones recently. Worth keeping an eye out. Issue is with the 1X/10X switch.

Sorry didn't quite catch that. Did you say that you'd "earned manure now"?

Even on quite good probes the 1X/10X switch is always the weak point.

[Zenith]

The heathkit HT supply is a notable bit of kit too. Good second hand market value 

Yeah, HT supplies are hard to come by. For some reason. I'm looking for a 6209, of course.

And it seems with the steady decrease in operating voltages for microprocessors that a lot of people will soon be thinking anything over fifteen volts is high voltage!

-Pat

ISTR an old video where Dave said he is scared with anything above 12Volts... since the day as a kid he got zapped while fiddling inside his parents television...

Getting a mains voltage shock off an old electric bar fire was what got me interested in electronics! I was about seven at the time...

I thought most of us interested in this stuff had had a few shocks in our youth; mains shocks from messing with things we shouldn't have, like connecting loudspeakers to the mains, shocks from spark plugs, shocks from capacitors, shocks from old radios we were messing with.....

[mnementh]

mnem
Electrons make me all tingly...

[Vince]

The Dwagon was cute as a little boy... his parents couldn't resist taking a picture of him discovering the world...

[tggzzz]

Where I grew up on the south coast almost all the older houses had basements (say pre-WWII), often with a street level hatch to deliver coal through. None of the houses I've lived in in London have had basements. Never really thought about the discrepancy until now and I can't offhand see geography being the motivating factor - Brighton is on, very wet, chalk and London is on a similarly wet [clay] river basin so they are both rather damp places for basements.

Colin Furze does offer some insights in building things underground in what I naîvely assume is somewhere in greater London area. His house didn't have a basement either..

https://youtu.be/A_ESR5zoGYQ

Nope, going by what he says in his video, he lives somewhere around the Stamford region as he mentions Rutland water is around 12 miles from his house.

Oh, my knowledge of UK geography is a bit spotty, isn't it London, the Fens, Wales and Scotland?

Not bad! Stamford is on the A1 Great North Road from London to Scotland. Although today Stamford is a long way inland, it used to be on the edge of the Fens before Vermuyden got to work and drained them.

[tautech]

The Dwagon was cute as a little boy... his parents couldn't resist taking a picture of him discovering the world...

Never was there better proof that too many zaps can change one's DNA so to produce scales rather than skin ! 

[tggzzz]

Celebrated my EEVblog 5 year anniversary with a curry, beer and some single ladies tonight at Namaste in Holborn  .

One of them has an electrical engineering degree. But she’s 15 years older than me 

Anyway enough slacking off. Getting home soon and will do a Vince and sort out my capacitors 

I've just had a nice molee, thoran and some appams with a young lady. Very nice. She insisted on paying for it too

But then I have been looking after her dog while she makes money, and sleeping on her couch last night and tonight. That wasn't in my life plan

[vk6zgo]

I actually have two low-distortion oscillators

Make that three -- I just remembered my hp telco test set, that while not very low indeed has bearable distortion.

Yeah. I have an AWA G232, which really is low distortion and a Philips PM5110 which is tolerably low distortion.

But that's not the point, you see a lot more distortion analysers/meters than oscillators fit to use with them, and it seems odd.

Maybe because the long line people looking after programme lines liked to have an N&D set in the rack at remote sites, but all the line tests were done, either from the Studios or a central test office.
Radio & TV transmitting sites normally had both, as we had to have a local low distortion source, independent of the programme line, for local testing.

The AWA audio generators & N&D sets of that generation were really excellent.
We had HP N&Ds for a while, but their automatic nulling was horrifically slow---OK for Labs, but not too good if you have multiple transmitters to test.
The AWA ones nulled much faster, & with a lot less messing round.

[Neomys Sapiens]

Speaking of coding and programming...

Anyone in need of a handful of NOS Motorola MC68705? Just found ten of them while I was looking for something else. Still no trace of something else, though.

So, been a few days, did anyone manifest interest beside me ?! 

I've not seen this post! I would be interested too..

I knew I should have PM'ed him rather posting here publicly, stupid me, now I will get only half of them ! 

Lesson learnt !   

No, you can have them. I confused the numbers.

[mnementh]

My current distraction...     

mnem
Caffeine levels dangerously low... must stop for refill...   

   Printed successfully, but too fine detail; not enough mass in the "snap-together" bits. They just fall apart.

In the middle of a complete redesign. You can click on the link above and see current iterations. New version should print well at 0.20LH, tho.

mnem
"The role of failure in design."

   Rev 11 printing. A wee bit more material now... 

mnem
          ...and there might have been a little scope creep; I should probably confer with my assistant, Mr Bluebottle fly...
*yawwnnnn*

      3D Model Web Viewer

This is somewhere around Rev 17; aboot half of which have actually been printed and test-fit. Finally have something I like the looks of that can actually be printed and assembled without major post-production fettling.

It can be a real dicksore trying to design something for other people to print and use... 

I added finger-grips to be able to pull the adapter out of the HP Pod, as that has quite a bit of hold with 40 pins all at once. Also a key-peg to match the slot on the pod as well.

Note that the back of the adapter has a slight taper away from the body of the scope so it doesn't make contact and scar up the panel. And yes, those are 1.6mm dia printed pins that lock the halves together. You can easily substitute any ~m2 screw you might want to use instead.

Now I need to get to work on Part 2 - a redesign to fit the original TK adapter, since he so graciously included both.

mnem
*toddles off to ded*

[cyclin_al]

This house was built in the 1850's and has a basement, with a dirt floor. There's even a small spring in one corner that comes to the surface and drains out through the foundation. But it does not smell musty or mildewed because there is good airflow.   

I suspect that's some critters living below trying 'to piss up a rope'!

Perhaps med could provide us a picture from this small spring? I'm finding this interesting.

I'll see if I can get into the basement and take a picture of it. It's not the first time I've seen a house built directly over a spring.

I'd have thought that it would contravene building regs as running water has the potential to flood the building or erode its footings and or make the fabric of the building damp making the ideal breeding ground for fungus etc and help cause breathing difficulties for the occupants.

Back in the old days, a spring was exactly where the "milk house" or "spring house" would be built.  The structure would be built of stone, and organic materials all removed.  The cold water continuously flowing would keep the milk bottles cold.   Yes, ventilation air should come into the structure at the same place the spring water comes in.

--the book I possess was first published in 1852.  No, I did not try building one of these ... yet

[srb1954]

The heathkit HT supply is a notable bit of kit too. Good second hand market value 

Yeah, HT supplies are hard to come by. For some reason. I'm looking for a 6209, of course.

You should perhaps also look at Kepco supplies. I have a ABC1000M which is quite an old design bit still a nice little unit that has excellent specs for its vintage. It puts out up to 1000V but at only 20mA and I use it as a bias source for testing HV electrolytics and HV semiconductors.

In the same ABC series Kepco have other models ranging from 200V to 2500V. There seems to be a few examples available on eBay at the moment.

[Robert763]

I actually have two low-distortion oscillators

Make that three -- I just remembered my hp telco test set, that while not very low indeed has bearable distortion.

Yeah. I have an AWA G232, which really is low distortion and a Philips PM5110 which is tolerably low distortion.

But that's not the point, you see a lot more distortion analysers/meters than oscillators fit to use with them, and it seems odd.

The reason is a lot more people know what an AF oscillator is and want one than those who know what a distortion analyser is (or want one). Thus the audio oscillator is kept and the analyser is sold.

[bd139]

To be fair the distortion analyser is mostly replaceable with a scope with an FFT these days for a “good enough” instrument on the audio side of things. And selling a distortion analyser will take the edge off the price of a scope with an FFT.

[david77]

mnem
Electrons make me all tingly...

Ha! That was me age 3 but not with SELV voltages like in the US. Proper European 230V! I can still remember that moment.

[med6753]

Somehow, it's fitting that should be your eleventy-leventy-leventh post, ya dirty-minded ol' reprobate... 

mnem
*dirty-minded ol' reptile*

 

[Zenith]

I actually have two low-distortion oscillators

Make that three -- I just remembered my hp telco test set, that while not very low indeed has bearable distortion.

Yeah. I have an AWA G232, which really is low distortion and a Philips PM5110 which is tolerably low distortion.

But that's not the point, you see a lot more distortion analysers/meters than oscillators fit to use with them, and it seems odd.

The reason is a lot more people know what an AF oscillator is and want one than those who know what a distortion analyser is (or want one). Thus the audio oscillator is kept and the analyser is sold.

There were always loads of low spec AF sig gens around in school labs or used in repair shops, but far fewer low distortion ones which would be suitable to use with a distortion analyser.  You explanation assumes audio oscillators and the matching analyser were sold in equal numbers. I think vk6zgo was on the money in that most analysers were checking an external high quality source, transmissions of some sort.

[med6753]

Going to make the trip across the pond today. TEK 8085 Interface and TEK P6460 Acquisition Probe. Purchaser confidential unless they chose to reveal themselves. Hopefully no hassles with customs.



TERRA Operative.....your package for some reason seems to be stuck in Osaka Customs. 

[Specmaster]

The Dwagon was cute as a little boy... his parents couldn't resist taking a picture of him discovering the world...

Yeah, most parents would be rushing to snatch the knife away from him at this point, so it begs the question, just what was their motive for not doing the same......

[tggzzz]

mnem
Electrons make me all tingly...

Ha! That was me age 3 but not with SELV voltages like in the US. Proper European 230V! I can still remember that moment.

I remember hearing of a case of a German kid and, knitting needles. It didn't end well.

Having lightly touched live thyristor case and neutral with each hand, I instantly came to appreciate that if you gripped the terminals then you wouldn't be able to let go.

[mansaxel]

There were always loads of low spec AF sig gens around in school labs or used in repair shops, but far fewer low distortion ones which would be suitable to use with a distortion analyser.  You explanation assumes audio oscillators and the matching analyser were sold in equal numbers. I think vk6zgo was on the money in that most analysers were checking an external high quality source, transmissions of some sort.

My set is a 3-position TM500 frame with SG502 and AA501A; I have the strong impression that Tek sold it as a kit. If you're going to do anything more complicated than syndicate someone else's program (or look into the studio-transmitter link), you'll have to have a bidirectional audio connection, to make an interview or just do talkback to people on mobile relays.

We used (at ${WORK}-2) to have analog mobile remotes; the contribution direction a mono wideband FM transmitter-receiver pair just below 300MHz, and the foldback direction a mono narrowband transmitter-receiver pair at ~450MHz, initially bodged from old MTD analog car phones (the system that predated the also analog NMT which the nordic Telcos deployed in the 80s) and later replaced with FM mobile radios. (typically a Moto GM300 or equivalent.)  The contribution direction was full program quality, 30-15000Hz and 70-80dB S/N. The foldback of course was typically 4KHz phone quality bandwidth.

Those got checked out in both directions to ensure level matching and quality.

Beyond that there of course also was analog "dry pairs" -- the last of which was in operation to around 2014, from the cathedral in Visby on the baltic island of Gotland, to the local radio station.  The longer inter-studio links and the studio-transmitter links were digital ITU-T J.57 from 1996 or so, where one does a bit of shoehorning to fit a AES-3 stereo pair into a ITU-T G.703 E1 link. Those are in theory (and proven in practice) perfect if there are no bit errors, so the wiggly meter and the  went away in favour of a BER counter..

Now it is all RTP over IP, both bit-reduced codecs like OPUS, MPEG-2 and APT-X and sometimes, for classic music, linear PCM. The lower-bandwidth foldback channel option has been kept; it is mostly SIP signalled, and it is quite possible to set up an assymetric link where A->B is stereo PCM and B->A is A-Law ITU-T G.711 mono...

[Specmaster]

What, where are all of these Tek fan boys then, still only a single bid as yet on this very unusual jigsaw of Jim Williams untidy bench, it ends in just under 30 minutes on eBay..

https://www.ebay.co.uk/itm/125424439942?.

[Robert763]

mnem
Electrons make me all tingly...

Ha! That was me age 3 but not with SELV voltages like in the US. Proper European 230V! I can still remember that moment.

Apparently at about age 3 I used a rat tail file to poke into a electrical box of some sort resulting in a big flash and a lot of consternation from mum. My dad also replaced the slotted screws on outlets etc with hex recess ones.....
At six I disassembled the family TV beyond repair.