Test Equipment Anonymous (TEA) group therapy thread

[med6753]

And speaking of vacuum tubes. The other day I mentioned that the 7586 nuvistor in the Type 321A is taking upwards of 30 minutes to stabilize. Well all of sudden the little nuvistor “woke up” and within 5 minutes or so is stable. Which is more than acceptable. I've seen this before especially with nuvistors and to a lesser extent with larger tubes. I have a theory as to what process is occurring here and I'd like some input.

As you know nuvistors are very small and almost look like a transistor. Inside there is a “getter” and it's function is to absorb any free gasses or ions floating around inside the vacuum envelope. Well after many years...20, 30, 40....of no applied power these gasses and ions may start break free from the getter and poison the cathode. And because of the small structures involved it doesn't take much for the cathode to get contaminated. Initially powering up after all those years those contaminates need to boil off the cathode and be absorbed by the getter again. But it may take many cycles for the cathode to clean itself.

Make sense or am I off base?

[Peter_O]

Talking of OXCO's I've been putting one of my HP 10811Ds into a case and fired it up for the first time on Tuesday. Frequency was fine with No EFC and the mechanical trimmer untouched since it was removed ftom a 8922 cell test set abou 4 years ago and has been in a storae container for at least a couple of years the error to GPS was 0.052Hz.
Overall I'm pretty pleased. I made one difficult decision to use a DC-DC converter so it can run off mains or 9-18V DC. I'm seeing a little bit of nise from the DC-DC on the output. It goes up with the oven current and appears to be short bursts of noise. It's good enough as a frequency reference but not to multiply up to microwavs frequencies. I'll have to do a bit of work and see if I can knock it down a bit further.

Almost looks like the case was once from a hp 220/221A, I hope I'm wrong.


David

You are not wrong, it used to be a 221A    However, in my defence, It was one of two that I rescued from from being scrapped. That one had very worn controls and switches. It was always tempermental and last time I powered it on it let the magic smoke out 
The second one was repaired and is used everyso often but they are not a great generator, completly uncalibrated.

To prevent these little guys form eradication I've just rescued one from the bay as the only bidder for 25 Euros   :-)

In 1972 HP catalogue it was probably the lowest cost device with 240$. Definitely the smallest in the pulse generator range, reaching up to a 8008A for 2,700$.

This one got some repairs obviously and is working. Max frequency is some 8 Mhz and at 1Mhz the function looks kind of square.

[bd139]

And speaking of vacuum tubes. The other day I mentioned that the 7586 nuvistor in the Type 321A is taking upwards of 30 minutes to stabilize. Well all of sudden the little nuvistor “woke up” and within 5 minutes or so is stable. Which is more than acceptable. I've seen this before especially with nuvistors and to a lesser extent with larger tubes. I have a theory as to what process is occurring here and I'd like some input.

As you know nuvistors are very small and almost look like a transistor. Inside there is a “getter” and it's function is to absorb any free gasses or ions floating around inside the vacuum envelope. Well after many years...20, 30, 40....of no applied power these gasses and ions may start break free from the getter and poison the cathode. And because of the small structures involved it doesn't take much for the cathode to get contaminated. Initially powering up after all those years those contaminates need to boil off the cathode and be absorbed by the getter again. But it may take many cycles for the cathode to clean itself.

Make sense or am I off base?

Possibly. I know from the Tek 453 i owned the thing was drifty until I zapped the nuvistor socket with switch cleaner.

I ashamedly scrapped that one eventually after finding the previous owner thought 1n4148’s were a good substitute for tunnel diodes and then the cat (now deceased - woohoo) pissed in it 

[BU508A]

There is a way of slowing down GAS (Gear Acquisition Syndrome) (stop gearoholics, don't hurt me yet). Demand of yourself that you have to build your gear yourself!

Here is a simple tube tester I recently finished.

The schematic is from Valve Heaven.

As always with test gear (and I've built a couple), it is the mechanical work that is the most cumbersome and takes a lot of time. In this example I used an old box that has 2 mm steel walls. Steel slows down your GAS quite a lot. Due to slow advancement there is risk though of periodically increasing abstinence symptoms. The cure for that is to acquire smaller things that you "need" for your current project (or maybe for your next project...).

That looks interesting. The low cost is definitely a plus. The others that I've seen on line of on YouTube were pretty damn expensive.

I found Tek's recommendation concerning tubes which is basically does it function properly in circuit? If yes, leave it alone. But for matching tubes that tester certainly can be valuable.   

The hardware of a tubetester is one thing, but I think the greater value of it lies in the database available. And in this respect, the Roetest from Helmut Weigl is unbeatable imho.

[JohanH]

I found Tek's recommendation concerning tubes which is basically does it function properly in circuit? If yes, leave it alone. But for matching tubes that tester certainly can be valuable.   

That is basically what is most useful with this tester. And you will easily find a tube that is out of spec. You can also vary the bias and calculate a rudimentary value of transconductance (GM). This is the so called "grid shift" technique of measuring transconductance.

It would be interesting to apply a signal to the grid and build a circuit at the plate to measure output AC current and show on a separate display. That would directly show the GM, but would make the device more complicated.

[factory]

Seems someone in Tasmania has stolen some of Med's blue spray paint, price is a little steep for a 50MHz scope. https://www.ebay.com/itm/284245054413



Anyone in Europe want to save an early hp 500A frequency meter? https://www.ebay.de/itm/324547765890



I've already got a 500A, which came from the collection of the late Marc Mislanghe, it all ended up with ePay seller f1power01 a few years ago.
https://www.hpmemoryproject.org/news/cat48/cat48_page_36.htm
https://www.hpmemoryproject.org/wa_pages/wall_a_page_11.htm

David

[med6753]

And speaking of vacuum tubes. The other day I mentioned that the 7586 nuvistor in the Type 321A is taking upwards of 30 minutes to stabilize. Well all of sudden the little nuvistor “woke up” and within 5 minutes or so is stable. Which is more than acceptable. I've seen this before especially with nuvistors and to a lesser extent with larger tubes. I have a theory as to what process is occurring here and I'd like some input.

As you know nuvistors are very small and almost look like a transistor. Inside there is a “getter” and it's function is to absorb any free gasses or ions floating around inside the vacuum envelope. Well after many years...20, 30, 40....of no applied power these gasses and ions may start break free from the getter and poison the cathode. And because of the small structures involved it doesn't take much for the cathode to get contaminated. Initially powering up after all those years those contaminates need to boil off the cathode and be absorbed by the getter again. But it may take many cycles for the cathode to clean itself.

Make sense or am I off base?

Possibly. I know from the Tek 453 i owned the thing was drifty until I zapped the nuvistor socket with switch cleaner.

I ashamedly scrapped that one eventually after finding the previous owner thought 1n4148’s were a good substitute for tunnel diodes and then the cat (now deceased - woohoo) pissed in it 

Previously when I saw this I also sprayed deoxit in the nuvistor socket but saw no change.....until after many power cycles.

If you want a 453/454 I know where there is one for approx $40 USD PLUS you get a 2nd parts unit for free. 

(No, I don't want it)

[Robert763]

There is a way of slowing down GAS (Gear Acquisition Syndrome) (stop gearoholics, don't hurt me yet). Demand of yourself that you have to build your gear yourself!

Here is a simple tube tester I recently finished.

The schematic is from Valve Heaven.

As always with test gear (and I've built a couple), it is the mechanical work that is the most cumbersome and takes a lot of time. In this example I used an old box that has 2 mm steel walls. Steel slows down your GAS quite a lot. Due to slow advancement there is risk though of periodically increasing abstinence symptoms. The cure for that is to acquire smaller things that you "need" for your current project (or maybe for your next project...).

It's even got a GAS TEST button   

[med6753]

Seems someone in Tasmania has stolen some of Med's blue spray paint, price is a little steep for a 50MHz scope. https://www.ebay.com/itm/284245054413





David

He should have masked off the feet before painting. Amateur. 

[factory]

Very Amateur as they forget to paint the inside of the lid too.

Strange the seller has all the power cords but can't be bothered to show it working, they claim it does.

David

[bd139]

And speaking of vacuum tubes. The other day I mentioned that the 7586 nuvistor in the Type 321A is taking upwards of 30 minutes to stabilize. Well all of sudden the little nuvistor “woke up” and within 5 minutes or so is stable. Which is more than acceptable. I've seen this before especially with nuvistors and to a lesser extent with larger tubes. I have a theory as to what process is occurring here and I'd like some input.

As you know nuvistors are very small and almost look like a transistor. Inside there is a “getter” and it's function is to absorb any free gasses or ions floating around inside the vacuum envelope. Well after many years...20, 30, 40....of no applied power these gasses and ions may start break free from the getter and poison the cathode. And because of the small structures involved it doesn't take much for the cathode to get contaminated. Initially powering up after all those years those contaminates need to boil off the cathode and be absorbed by the getter again. But it may take many cycles for the cathode to clean itself.

Make sense or am I off base?

Possibly. I know from the Tek 453 i owned the thing was drifty until I zapped the nuvistor socket with switch cleaner.

I ashamedly scrapped that one eventually after finding the previous owner thought 1n4148’s were a good substitute for tunnel diodes and then the cat (now deceased - woohoo) pissed in it 

Previously when I saw this I also sprayed deoxit in the nuvistor socket but saw no change.....until after many power cycles.

If you want a 453/454 I know where there is one for approx $40 USD PLUS you get a 2nd parts unit for free. 

(No, I don't want it)

Gah don’t want it. Still arguing with that D755  .

Today’s task is measuring crystals. Got 200 of them that need motional parameter analysis done on them. This is going to be a job for python, GPIB and arduino hack job 

[JohanH]

The hardware of a tubetester is one thing, but I think the greater value of it lies in the database available. And in this respect, the Roetest from Helmut Weigl is unbeatable imho.

I've read about https://www.dos4ever.com/uTracer3/uTracer3_pag0.html, which seems impressing. Don't have a need for a curve tracer right now, though.

[factory]

And speaking of vacuum tubes. The other day I mentioned that the 7586 nuvistor in the Type 321A is taking upwards of 30 minutes to stabilize. Well all of sudden the little nuvistor “woke up” and within 5 minutes or so is stable. Which is more than acceptable. I've seen this before especially with nuvistors and to a lesser extent with larger tubes. I have a theory as to what process is occurring here and I'd like some input.

As you know nuvistors are very small and almost look like a transistor. Inside there is a “getter” and it's function is to absorb any free gasses or ions floating around inside the vacuum envelope. Well after many years...20, 30, 40....of no applied power these gasses and ions may start break free from the getter and poison the cathode. And because of the small structures involved it doesn't take much for the cathode to get contaminated. Initially powering up after all those years those contaminates need to boil off the cathode and be absorbed by the getter again. But it may take many cycles for the cathode to clean itself.

Make sense or am I off base?

Makes sense to me, Shango066 on youtube has had this happen with old TVs/radios that haven't been used for decades, they can get better with extended use. But not always, sometimes they are knackered and that was the reason they got retired from use in the first place.

Re: trying to rejuvenate Trintron CRT's from a few pages back, Shango066 has tried & failed with a knackered one at some point in the last year, I'm sure he said it rarely works with Trintron CRT's and can sometimes make them worse. If a brightner was fitted then it's probably a waste of time trying to rejuvenate them.

David

[BU508A]

The hardware of a tubetester is one thing, but I think the greater value of it lies in the database available. And in this respect, the Roetest from Helmut Weigl is unbeatable imho.

I've read about https://www.dos4ever.com/uTracer3/uTracer3_pag0.html which seems impressing. Don't have a need for a curve tracer right now, though.

Fixed that for you.   

[BU508A]

Today’s task is measuring crystals. Got 200 of them that need motional parameter analysis done on them. This is going to be a job for python, GPIB and arduino hack job 

I'm having here some crystals laying around which I could send you. Shall I?   

[tautech]

Seems someone in Tasmania has stolen some of Med's blue spray paint, price is a little steep for a 50MHz scope. https://www.ebay.com/itm/284245054413





David

He should have masked off the feet before painting. Amateur. 

Doesn't tggzzz have one of these ?
IIRC his is unblued !

[factory]

Talking of OXCO's I've been putting one of my HP 10811Ds into a case and fired it up for the first time on Tuesday. Frequency was fine with No EFC and the mechanical trimmer untouched since it was removed ftom a 8922 cell test set abou 4 years ago and has been in a storae container for at least a couple of years the error to GPS was 0.052Hz.
Overall I'm pretty pleased. I made one difficult decision to use a DC-DC converter so it can run off mains or 9-18V DC. I'm seeing a little bit of nise from the DC-DC on the output. It goes up with the oven current and appears to be short bursts of noise. It's good enough as a frequency reference but not to multiply up to microwavs frequencies. I'll have to do a bit of work and see if I can knock it down a bit further.

Almost looks like the case was once from a hp 220/221A, I hope I'm wrong.


David

You are not wrong, it used to be a 221A    However, in my defence, It was one of two that I rescued from from being scrapped. That one had very worn controls and switches. It was always tempermental and last time I powered it on it let the magic smoke out 
The second one was repaired and is used everyso often but they are not a great generator, completly uncalibrated.

To prevent these little guys form eradication I've just rescued one from the bay as the only bidder for 25 Euros   :-)

In 1972 HP catalogue it was probably the lowest cost device with 240$. Definitely the smallest in the pulse generator range, reaching up to a 8008A for 2,700$.

This one got some repairs obviously and is working. Max frequency is some 8 Mhz and at 1Mhz the function looks kind of square.

You've beat me to posting pictures of mine, ended up very tired & knackered after my first week back at work since last year. 

Haven't seen one listed in the UK for years, ended up buying my 221A last month from a US seller.
There does seem to be a lack of any manuals (real or pdf) available though, maybe that was why Robert murdered his. 
Need to find the 220A to go with it too.

Letting the smoke out is a feature of HP generators around that era. Also gratuitous annoying use of tunnel diodes and unobtainium hybrid ASICs

I'm not seeing any tunnel diodes or ASICs unless my eyesight needs testing, this is a 1960's design by the way, supposed to be good for 10MHz.

David

[tautech]

Still arguing with that D755  .

What's up with it now ?
Penis fingers by any chance ?

[med6753]

Seems someone in Tasmania has stolen some of Med's blue spray paint, price is a little steep for a 50MHz scope. https://www.ebay.com/itm/284245054413





David

He should have masked off the feet before painting. Amateur. 

Doesn't tggzzz have one of these ?
IIRC his is unblued !

No, his is a TDR. Tek 1502 I think.

[med6753]

Very Amateur as they forget to paint the inside of the lid too.

Strange the seller has all the power cords but can't be bothered to show it working, they claim it does.

David

I'll give him a pass on not painting the inside front cover. I didn't paint the inside front cover of the Type 422. It didn't need it.

But if you look close he didn't mask off the cover latches. That's less than amateur. 

Agreed, no pix of powered up. Suspicious.   

[BU508A]

This guy from Tasmania painted it not in Smurf Tek blue. This is more turquoise, I think.

Smurf Tek blue:


Tasmania Tek blue:

[Specmaster]

yawwwwwwwnnnnnn...

I got this far before I had to pull the plug for my own safety; I found myself waking up to the tone of the iron going to sleep. While it was still in my hand.

Tomorrow's a chance for all new mistakes.

mnem
 

Been there before, scary. That said, often I have my best flashes of inspiration after everyone else has gone to bed 

[beanflying]

Very Amateur as they forget to paint the inside of the lid too.

Strange the seller has all the power cords but can't be bothered to show it working, they claim it does.

David

I'll give him a pass on not painting the inside front cover. I didn't paint the inside front cover of the Type 422. It didn't need it.

But if you look close he didn't mask off the cover latches. That's less than amateur. 

Agreed, no pix of powered up. Suspicious. 

Circa 2500 listings of crap and ONE bit of test gear so I call NFI or clue just lucky it didn't get the light bulb steampunk treatment 

[bd139]

Still arguing with that D755  .

What's up with it now ?
Penis fingers by any chance ?

Nope HT issues 

[factory]

Very Amateur as they forget to paint the inside of the lid too.

Strange the seller has all the power cords but can't be bothered to show it working, they claim it does.

David

I'll give him a pass on not painting the inside front cover. I didn't paint the inside front cover of the Type 422. It didn't need it.

But if you look close he didn't mask off the cover latches. That's less than amateur. 

Agreed, no pix of powered up. Suspicious.   

Was the Tek 422 a completely different color inside? The covers for that HP should really be school bus yellow all over.

David