Test Equipment Anonymous (TEA) group therapy thread

[med6753]

It happens every year. First snow and it's like people forget how to slow down and thread lightly.

Cars into trees, telephone poles, into ditches, and into each other. 

[med6753]

Meets quite a few criteria,
Test equipment tick
Nixie tube tick
Ham related tick
It works tick
Happy camper here

Does need sl weird power supply (220v, we have 240v and with all the solar feed in, it often hits 250v)

West Oz used to be 250v, & plenty of devices with supposedly lower voltage ratings operated merrily for decades.

As factory has pointed out, the thing has adjustable transformer primary taps.
A "234" volt setting will operate ok on 250v "till the cows come home".

All my old Tek iron says "wired for 117VAC" but has no issue with my mains usually up around 125VAC.

It's the real old stuff, like the 5 tube series string radios, that say "110VAC or DC" that you have to be mindful of. Especially if you change out the B+ selenium rectifier for a sillycon diode.   

[TERRA Operative]

Hmm, gotta make a circuit up to test my HP 10811 OCXO, figured I'll make a nice-ish one to make things easy and reusable.

Anyone know of a relatively simple way to make an adjustable -5 to +5VDC voltage from a supply voltage of around +20-30VDC (For the EFC control)?

I used a small (1W) 12V output isolated DC-DC converter with lots of fitering and two 5V references in series. Common is junction of 5V refs and output was a 10T pot across the 10V giving +- 5V

Can you elaborate slightly, my tired dumb brain is having trouble picturing it.....

[Cerebus]

My experience is at both ends of the pendulum.  Some of the best thinkers and productive workers have been Millennials.  The worst ones that I have seen are also Millennials, absolutely full of entitlement and laziness.
I suspect none of them are going to last long though, either being let go or burning out...

After most of a lifetime, my experience is simply summed up as "There are good X people, there are bad X people", for X= {old, young, black, white, piebald, tall, short, fat, thin, US, UK, etc etc etc}.

Don't lazily pigeon-hole a person, unless you want to be like most (but not all) human resources droids.

I wouldn't disagree, but would add "There are bad people who can be turned into good people if you treat them the right way, and there are good people who can be turned into bad people if you treat them the wrong way.". In my experience most managers/corporations are poor at the former and excel at the latter, oft-times by inventing rigid "one size fits all" rules.

[vk6zgo]

We had a lot of stuff round the various stations with large, fancy chrome "Fernseh" badges.

One of those is still decorating a shelf in my office.

The company was called Fernseh GmbH ("Television Ltd.") from 1939 to 1972, later Bosch Fernsehanlagen GmbH, then Broadcast Television Systems (BTS) in a joint venture with Philips and later went through various hands including Thomson and Belden. The remains are now known as Grass Valley Germany.

Oh how the mighty have fallen!

I am glad that my recollection was correct, & those folk who said otherwise were wrong.
It seems there are quite a lot of such bulldust merchants around----I remember some allegedly ex-Tektronix guys trying to tell us that the seriously dire Tek 650 series of picture monitors were really "all made by Sony!'.

Funny thing, they all had "Beaverton , Oregon" all over them!

[xrunner]

I found the problem with the hp 8904A keys. A ribbon cable connecting the front PCB to the top PCB in the main chassis. I re-seated all the cables at first but the problem didn't go away. It did change a bit in that some keys that were not working before started to, and some that were - stopped working. So I was onto to something. Then I bet the money on J1. I remembered looking at it that I wasn't very impressed with the choice of cable connector when I took the whole thing apart after I first got it.

I have never seen that selection of cable and connector in any other hp gear - have any of you? I don't know how the end with the pins was made, it doesn't look like an end connector that you could make a direct replacement for at home. Looks like it was fabricated at the connector factory and shipped to hp ... ? Anyway it may have been the first and last time it was used by hp, and for good reason.

Anyway, I pulled the connector for the second time, and cleaned it with alcohol, and wiped with some contact enhancer, and the second time it was fixed.

The hp 8804A Multifunction Synthesizer is an interesting bit of kit though. It has four channels internally - each one can be set up to generate a certain waveform (freq,. amplitude, phase, and type (sine, square, noise, etc.). Then these channels can be combined together internally to make any sort of output you want. In fact, had to glance back at the operations manual to remember how to get it going after three years. The fact that only some keys were not working made me think I was not doing things the way it wanted. Pic shows sine and square wave with noise intentionally added.

[Cerebus]

Hmm, gotta make a circuit up to test my HP 10811 OCXO, figured I'll make a nice-ish one to make things easy and reusable.

Anyone know of a relatively simple way to make an adjustable -5 to +5VDC voltage from a supply voltage of around +20-30VDC (For the EFC control)?

Quick and dirty:



Might need tweaking if Z_in isn't >> 10k.

[vk6zgo]

Meets quite a few criteria,
Test equipment tick
Nixie tube tick
Ham related tick
It works tick
Happy camper here

Does need sl weird power supply (220v, we have 240v and with all the solar feed in, it often hits 250v)

West Oz used to be 250v, & plenty of devices with supposedly lower voltage ratings operated merrily for decades.

As factory has pointed out, the thing has adjustable transformer primary taps.
A "234" volt setting will operate ok on 250v "till the cows come home".

All my old Tek iron says "wired for 117VAC" but has no issue with my mains usually up around 125VAC.

It's the real old stuff, like the 5 tube series string radios, that say "110VAC or DC" that you have to be mindful of. Especially if you change out the B+ selenium rectifier for a sillycon diode.

Such horrors were rare in Oz----radios, as a class, were more expensive, power transformers were reasonably cheap, & the tube manufacturers didn't want to tool up for series string tubes.

[Cerebus]

   Heh... that logo looks so nefarious, like something out of The Prisoner... 

Huh... AMC did a remake in 2009, with Ian McKellen & Jim Caviezel: https://www.imdb.com/title/tt1043714/

mnem
 

Oh god, I bet that was a car crash to watch, rather like the recent BBC reimagining of Terry's City Guards in "The Watch".

[Robert763]

Hmm, gotta make a circuit up to test my HP 10811 OCXO, figured I'll make a nice-ish one to make things easy and reusable.

Anyone know of a relatively simple way to make an adjustable -5 to +5VDC voltage from a supply voltage of around +20-30VDC (For the EFC control)?

I used a small (1W) 12V output isolated DC-DC converter with lots of fitering and two 5V references in series. Common is junction of 5V refs and output was a 10T pot across the 10V giving +- 5V

DC- DC converter gives a isolated 12V (or 15). Connect "anode" of 1st 5V shunt regulator and CCW end of 10T pot ( I used 10k) to 0V output of converter. Connect "cathode of 1st shunt regulator to "anode" of 2nd 5V shunt regulator AND COMMON of the 10811 oscillator circuit. Connect "cathode" of 2nd shunt regulator to CW end of 10T pot and via current limiting resistor to converter +12V output. The current limiting resistor only needs to pass a few mA. For a 10k pot 1mA through the pot and say 2mA trough references. A 1K is OK.
I actually used a 15V DC-DC and two 6.2V temperature compensated zeners. A  1.2k resistor at each end of the 10k 10T pot limited the span to +-5V

[Neper]

Oh how the mighty have fallen!

They had a monopoly at a time when all German state broadcasters (there were no commercial stations) had to be fitted from scratch for b/w and then in 1967 for colour tv. This clearly couldn't go on forever.

It wasn't only them. Mostly all German makers of broadcast equipment were living in a land where milk and honey flowed in endless abundance. The stations had money 'like hay', as we say here. Only the best was good enough and discussing prices was just not done.

This changed with the arrival of commercial broadcasters who, by their very nature, had to be cost-conscious. Most of the great old names didn't survive the next decade.

[med6753]

.....snip

It seems there are quite a lot of such bulldust merchants around----I remember some allegedly ex-Tektronix guys trying to tell us that the seriously dire Tek 650 series of picture monitors were really "all made by Sony!'.

Funny thing, they all had "Beaverton , Oregon" all over them!

They might have been partially correct. Sony learned a lot from Tek on CRT manufacturing and applied that to the development of the Trinitron CRT. It's possible that those monitors had a Trinitron CRT but were still built in Beaverton. 

[Vince]

I found the problem with the hp 8904A keys. A ribbon cable connecting the front PCB to the top PCB in the main chassis. I re-seated all the cables at first but the problem didn't go away. It did change a bit in that some keys that were not working before started to, and some that were - stopped working. So I was onto to something. Then I bet the money on J1. I remembered looking at it that I wasn't very impressed with the choice of cable connector when I took the whole thing apart after I first got it.

I have never seen that selection of cable and connector in any other hp gear - have any of you? I don't know how the end with the pins was made, it doesn't look like an end connector that you could make a direct replacement for at home. Looks like it was fabricated at the connector factory and shipped to hp ... ? Anyway it may have been the first and last time it was used by hp, and for good reason.

Anyway, I pulled the connector for the second time, and cleaned it with alcohol, and wiped with some contact enhancer, and the second time it was fixed.

The hp 8804A Multifunction Synthesizer is an interesting bit of kit though. It has four channels internally - each one can be set up to generate a certain waveform (freq,. amplitude, phase, and type (sine, square, noise, etc.). Then these channels can be combined together internally to make any sort of output you want. In fact, had to glance back at the operations manual to remember how to get it going after three years. The fact that only some keys were not working made me think I was not doing things the way it wanted. Pic shows sine and square wave with noise intentionally added.

Sounds like a nice device indeed.. a bit like an AWG but less general purpose, offering an easier, quicker more intuitive way of creating test signals for most common scenarios.

Question : you didn't say what frequency your test signal is.. but the instrument is limited to 600kHz so let's say it's that.
I notice on the your scope that the square wave looks ridiculously crap, I mean the rise and fall times are so slow you can actually see it on the screen....
There is no way an HP gear, especially of that vintage, of that caliber, would have such a slow rise time... does that mean it's slow on purpose, for some reason to do with the intended use of this piece of gear ? Does the user manual say anything about that ? Or is it capable of much faster rise times but it's user adjustable and your unit happens to be configured right now for slow rise times ?

[mnementh]

I found the problem with the hp 8904A keys...   

Uggghhh... looking at that connector, it seems it would be dreadfully sensitive to any tiny misalignment caused by bent pins or by the front panel being pulled by attachment screws. Myself I'd probably get my smooth-jawed pliers after them and make sure they are all absolutely straight and in line, but that's a gut reaction just looking at those pics.

Doesn't seem like the best choice in this application for sure; generally want to have a little wiggle room built-in such that when seated, the contact points "float" independently (even if just a fraction of a mm) of whatever rigid part they're connecting to so that the aggregate tension of the contact springs can "self-align" all the contacts in the connector matrix as the screws are tightened down. Even old-fashioned 0.100" IDC connectors have this to a certain extent... 

Good luck; if it exhibits any recidivism, I'd try very carefully straightening/realigning the pins; maybe cleaning/re-tensioning the contact spring leaves in the socket with a sewing needle if access is possible with the panel removed.

mnem
 

[mnementh]

Hmm, gotta make a circuit up to test my HP 10811 OCXO, figured I'll make a nice-ish one to make things easy and reusable.

Anyone know of a relatively simple way to make an adjustable -5 to +5VDC voltage from a supply voltage of around +20-30VDC (For the EFC control)?

Quick and dirty:      Might need tweaking if Z_in isn't >> 10k.

DC- DC converter gives a isolated 12V (or 15). Connect "anode" of 1st 5V shunt regulator and CCW end of 10T pot ( I used 10k) to 0V output of converter. Connect "cathode of 1st shunt regulator to "anode" of 2nd 5V shunt regulator AND COMMON of the 10811 oscillator circuit. Connect "cathode" of 2nd shunt regulator to CW end of 10T pot and via current limiting resistor to converter +12V output. The current limiting resistor only needs to pass a few mA. For a 10k pot 1mA through the pot and say 2mA trough references. A 1K is OK.
I actually used a 15V DC-DC and two 6.2V temperature compensated zeners. A  1.2k resistor at each end of the 10k 10T pot limited the span to +-5V

Noice Robert-CAD !  and noice C-CAD too! A twofer on the same project!

So professional; not scribbled on the corner of a napkin nor nuthin' ! 

mnem
 

[med6753]

First test of the Type W plug-in. It works but very unstable. This is a differential between a triangle and sine of the same frequency/amplitude.
The issue is the input attenuator switch deck is very noisy and under multiple shields. I have to figure out how to get in there and deoxit. It also appears that the overall DC balance is out to lunch but that could be because it's not fully warmed up.

An update later. Considering how dirty these plug-in's were it's a miracle they work at all. 

[xrunner]

Sounds like a nice device indeed.. a bit like an AWG but less general purpose, offering an easier, quicker more intuitive way of creating test signals for most common scenarios.

Question : you didn't say what frequency your test signal is.. but the instrument is limited to 600kHz so let's say it's that.
I notice on the your scope that the square wave looks ridiculously crap, I mean the rise and fall times are so slow you can actually see it on the screen....
There is no way an HP gear, especially of that vintage, of that caliber, would have such a slow rise time... does that mean it's slow on purpose, for some reason to do with the intended use of this piece of gear ? Does the user manual say anything about that ? Or is it capable of much faster rise times but it's user adjustable and your unit happens to be configured right now for slow rise times ?

600 kHz max for sine, 50 kHz for the other waveforms. No, it isn't gear designed for high frequency applications. I included the sales brochure below. The stated rise time for a square wave is "< 2.5 uS" and that's about what I'm seeing. This is gear for testing audio and low frequency systems.

Stimulus for audio circuits

"The 8904A has many characteristics
and features which make it well suited
as a stimulus for audio circuits. The
output of the 8904A is characterized
by low spurious and harmonic content.
Total harmonic distortion plus noise
(including all spurs) can be as low as
–78 dBc. With low distortion, the
8904A can be used to test many high
performance audio devices."

[mnementh]

   Heh... that logo looks so nefarious, like something out of The Prisoner... 

Huh... AMC did a remake in 2009, with Ian McKellen & Jim Caviezel: https://www.imdb.com/title/tt1043714/

mnem
 

Oh god, I bet that was a car crash to watch, rather like the recent BBC reimagining of Terry's City Guards in "The Watch".

This one...? But it has Vince Vaughn and that guy from The IT Crowd... come now, there has to be some redeeming quality in there... 

As for The Prisoner₂₀₀₉ , I'm tempted to look it up, just to see Sir Ian as Number 1...  Having to put up with Caviezel's ham-fisted acting would surely test my resolve, however.

mnem

[Vince]

Sounds like a nice device indeed.. a bit like an AWG but less general purpose, offering an easier, quicker more intuitive way of creating test signals for most common scenarios.

Question : you didn't say what frequency your test signal is.. but the instrument is limited to 600kHz so let's say it's that.
I notice on the your scope that the square wave looks ridiculously crap, I mean the rise and fall times are so slow you can actually see it on the screen....
There is no way an HP gear, especially of that vintage, of that caliber, would have such a slow rise time... does that mean it's slow on purpose, for some reason to do with the intended use of this piece of gear ? Does the user manual say anything about that ? Or is it capable of much faster rise times but it's user adjustable and your unit happens to be configured right now for slow rise times ?

600 kHz max for sine, 50 kHz for the other waveforms. No, it isn't gear designed for high frequency applications. I included the sales brochure below. The stated rise time for a square wave is "< 2.5 uS" and that's about what I'm seeing. This is gear for testing audio and low frequency systems.

Stimulus for audio circuits

"The 8904A has many characteristics
and features which make it well suited
as a stimulus for audio circuits. The
output of the 8904A is characterized
by low spurious and harmonic content.
Total harmonic distortion plus noise
(including all spurs) can be as low as
–78 dBc. With low distortion, the
8904A can be used to test many high
performance audio devices."

OK OK......so... answer is, it's slow on purpose due to the intended usage of this kit...

[TERRA Operative]

Anyone in Germany have some spare cash to spend?

https://www.ebay.com/itm/353785283417

[tggzzz]

My experience is at both ends of the pendulum.  Some of the best thinkers and productive workers have been Millennials.  The worst ones that I have seen are also Millennials, absolutely full of entitlement and laziness.
I suspect none of them are going to last long though, either being let go or burning out...

After most of a lifetime, my experience is simply summed up as "There are good X people, there are bad X people", for X= {old, young, black, white, piebald, tall, short, fat, thin, US, UK, etc etc etc}.

Don't lazily pigeon-hole a person, unless you want to be like most (but not all) human resources droids.

I wouldn't disagree, but would add "There are bad people who can be turned into good people if you treat them the right way, and there are good people who can be turned into bad people if you treat them the wrong way.". In my experience most managers/corporations are poor at the former and excel at the latter, oft-times by inventing rigid "one size fits all" rules.

Most of my career was spent in Theory Y companies, where it is assumed that people want to work and do a good job. All you have to do is let them.

The "one size fits all" is probably drummed into young impressionable managers by HR religion - you have to treat all your resources equally and not show favouritism. I find that repellent; it will be interesting to see if it changes after covid.

My basic attitude is tit-for-tat (as in Prisoners's Dilemma strategy). Start by assuming good and being very cooperative/helpful/etc. If an idiot doesn't reciprocate, then I do unto them as they do unto me.

[tggzzz]

   Heh... that logo looks so nefarious, like something out of The Prisoner... 

Huh... AMC did a remake in 2009, with Ian McKellen & Jim Caviezel: https://www.imdb.com/title/tt1043714/

mnem
 

Oh god, I bet that was a car crash to watch, rather like the recent BBC reimagining of Terry's City Guards in "The Watch".

I'll bet there was a "whoosh", as the soul of the original whizzed past them into the distance. It probably wasn't loud enough for them to have noticed.

[tggzzz]

So professional; not scribbled on the corner of a napkin nor nuthin' ! 

Even better would be to have an entire working application, e.g. this is a functional IntelliJ IDE skinned with http://napkinlaf.sourceforge.net/

[Neper]

Anyone in Germany have some spare cash to spend?

https://www.ebay.com/itm/353785283417

96 euros shipping within Germany. Delivery by silver platter? Magic carpet?

[THDplusN_bad]

I found the problem with the hp 8904A keys. [..]

I have never seen that selection of cable and connector in any other hp gear - have any of you? I don't know how the end with the pins was made, it doesn't look like an end connector that you could make a direct replacement for at home. Looks like it was fabricated at the connector factory and shipped to hp ... ? Anyway it may have been the first and last time it was used by hp, and for good reason.

Anyway, I pulled the connector for the second time, and cleaned it with alcohol, and wiped with some contact enhancer, and the second time it was fixed.
[..]

Well done, xrunner! 
Yes, I agree - those connectors are evil. You were absolutely right when you have used some "contact enhancer".

My recommendation to any 8904A-owner: Apply a gentle dose of corrosion prevention for these electrical contacts (after some straightening). I have seen at least one 8904A unit with severely corroded contacts. You can just see it in the open construction

Cheers,

THDplusN_bad