Test Equipment Anonymous (TEA) group therapy thread

[bd139]

"if you can't be with one you love......love the one you're with"

Experience suggests that is bad advice 

[THDplusN_bad]

Greetings to the group,

I trust you chaps can understand my joy - as I have successfully beaten a GRUNDIG mV-meter with integrated oscilloscope into submission 
I have re-visited it after 8 years of pause... This one is exactly 50 years old

Cheers,

THDplusN_bad


 

[Robert763]

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.

I went overboard with mine: capacitance multiplier, 723 regulator (since the diode is low noise), and ferrites/caps. I may be able to provide a screenshot later

Screenshots using a Tek 492AP (red) and HP8562B (green). Note the different horizontal scales, but both are 3Hz VBW and 100Hz RBW.

IIRC the capacitance multiplier feeds both the oven and 723, the 723 feeds the oscillator only. The case is diecast ali, and the PSU is an external linear supply.

Thanks for posting that. It is good to have a comparison. Mine is not miles away but is detectably noisier on the DC-DC. So I set up to do some more investigation. I separated out the DC-DC board and arranged some Molex  0.1" plugs so I can swap supplies around. First test is oven disconnected and oscillator and EFC (+_5V) supply run from a external linear +_ 15V  supply. No detetable noise on the output with DC-DC running or not, or with it loaded with a power resistor.
I then connected ONE side of the oven circuit (which is isolated from the oscillator) to the -15V output of the DC-DC converter. This produced noticable noise on the output which increased when the converter output was loaded. Connecting both sides of the heater to the converter increased the noise significatly. Connecting the DC-DC output common to chassis (the designed configuration) improved things but noise is still there. Adding capcitors across the supply or to ground makes little or no difference. Series inductance made it worse and even connecting the heater circuit via a 47pF series capacitor gave the same noise on the output.
Investigation with a current probe  (Tek P6019) showed bursts of high frequency noise repeating at about 250kHz rate (approx switching freq).
Twas getting late so as a quick check I stuck a couple of bolt in feed-through capacitors in holes in the side frame and fed the heater circuit through those. This seems to fix the noise on the output but I need to investigate further.
Capacitor lead length DOES matter.
 

[cyclin_al]

For some reason, every time I go to page 3496, I get logged out....

Reply #87379 to McBryce:

I was actually playing on the stereotype of Hockey.  I suppose I was too subtle.  Yes, i know most of the world does not play hockey.  If you look at the statistics, more Canadians play soccer than play hockey.
I know too that the rest of the world calls it football, which is a more sensible name since you play the ball with your foot.

The interesting part was kicking off the whole conversation on dexterity and the various different manners everyone functions.

[med6753]

"if you can't be with one you love......love the one you're with"

Experience suggests that is bad advice 

Oh hell yes. 

[BU508A]

Incoming DL1200A here by next week. 

Hmmm... are you a Yokiogawa lover, collecting them ?!

No, not really, but I'm somewhat fascinated by their (to me) unusual look.
Actually, I wanted a DL1640 but they are rare and expensive.
This DL1200A is looking very nice and for 150 Euro it is a nice unit.
But I'm still looking for a DL1640.

The DL1200A which should arrive by mid of next week. Hopefully in one piece, will remind the seller to pack it carefully.

They aren't very common in France at the very least. Never everheard about them in my entire live. I became aware of them only recently as I was searching the local ads fr the keyword "oscilloscope"... a Yokogawa popped up, wondered what the hell that was. Looked like some medical gear or something...  was curious to play with one but it was not to be, since the sellers wanted a delirious amount of money given the poor specs of the scope.

Yeah, no idea, why some people are thinking, they are sitting on a pile of gold. 

Will do then a teardown of it.

Would be curious to see that. When you do, please post a link to it here, so I don't miss it 

Be assured, I'll post it here and ask bitseeker to add it to the POI on the first page. 
I'd also recommend to write poor bitseeker a PM if you have something for the POI list.
I'm convinced, some interesting stuff is missing in this list on the first page, which is really a pity,
but he has a very busy job and also other things to do than doing a catch-up of this fast-moving  thread.

[tautech]

Does any of you lot have something to confess?

Only the box full of 100-600 MHz 10x autosense scope probes ordered last week have arrived.

Time to pull out the SA and sweep them all to see if they're any good. 

Preliminary results. 10 MHz to 1 GHz sweep @ 0dBm.
100, 350, 500 and 600 MHz probes compared against the 500 MHz SP3050A probe used to Normalize.
N-BNC with BNC-probe tip adapters used on the TG output and N-BNC on RF In. All included in Normalize of course.

All probes compensated on a SDS5104X prior to testing.

[Kosmic]

Does any of you lot have something to confess?

Only the box full of 100-600 MHz 10x autosense scope probes ordered last week have arrived.

Time to pull out the SA and sweep them all to see if they're any good. 

Preliminary results. 10 MHz to 1 GHz sweep @ 0dBm.
100, 350, 500 and 600 MHz probes compared against the 500 MHz SP3050A probe used to Normalize.
N-BNC with BNC-probe tip adapters used on the TG output and N-BNC on RF In. All included in Normalize of course.

All probes compensated on a SDS5104X prior to testing.

I guess those probes are normal oscilloscope probes and require a 1M\$\Omega\$ input. Not 50\$\Omega\$ like the input of your Spectrum analyzer. The impedance problem might explain the waves we are seeing. Hard to draw any conclusion from your experiment. Normally you should see a nice slope going down as frequency increase. The waves are not a good sign.

Also probes compensation is only valid on the oscilloscope where the probe are compensated. You can't really disconnect them and try to use them elsewhere and hope that the probe will still be compensated.

Personally I would do the same experience with a signal generator and a oscilloscope and a 50\$\Omega\$ termination between the signal and the probe. Maybe you could automate the process ?

[tautech]

I guess those probes are normal oscilloscope probes and require a 1M\$\Omega\$ input. Not 50 like the input of your Spectrum analyzer. The impedance problem might explain the waves we are seeing. Hard to draw any conclusion from your experiment. Normally you should see a nice slope going down as frequency increase. The waves are not a good sign.

Also probes compensation is only valid on the oscilloscope where the probe are compensated. You can't really disconnect them and try to use them elsewhere and hope that the probe will still be compensated.

Personally I would do the same experience with a signal generator and a oscilloscope and a 50\$\Omega\$ termination between the signal and the probe.

Yep understood and it was just an initial experiment to get some preliminary results comparing apples with apples using the standard 500 MHz probe as the reference (0dB).

3.2 GHz sig gen sweeps are next however we can only rely on its output flatness for accuracy as I don't yet have a $ $ level sensor. 
Maybe tonight as have some paint to get on outside before forecast rain arrives.

[Kosmic]

I guess those probes are normal oscilloscope probes and require a 1M\$\Omega\$ input. Not 50 like the input of your Spectrum analyzer. The impedance problem might explain the waves we are seeing. Hard to draw any conclusion from your experiment. Normally you should see a nice slope going down as frequency increase. The waves are not a good sign.

Also probes compensation is only valid on the oscilloscope where the probe are compensated. You can't really disconnect them and try to use them elsewhere and hope that the probe will still be compensated.

Personally I would do the same experience with a signal generator and a oscilloscope and a 50\$\Omega\$ termination between the signal and the probe.

Yep understood and it was just an initial experiment to get some preliminary results comparing apples with apples using the standard 500 MHz probe as the reference (0dB).

3.2 GHz sig gen sweeps are next however we can only rely on its output flatness for accuracy as I don't yet have a $ $ level sensor. 
Maybe tonight as have some paint to get on outside before forecast rain arrives.

Yeah you could let the sig gen sweep slowly and but the oscilloscope in FFT max hold. That would probably do the trick.

[Kosmic]

Your current setup with the spectrum analyzer would work for RF probes (that use 50\$\Omega\$ input) but you would still need to terminate the signal coming out of the tracking gen and probe at the termination.

[tautech]

I guess those probes are normal oscilloscope probes and require a 1M\$\Omega\$ input. Not 50 like the input of your Spectrum analyzer. The impedance problem might explain the waves we are seeing. Hard to draw any conclusion from your experiment. Normally you should see a nice slope going down as frequency increase. The waves are not a good sign.

Also probes compensation is only valid on the oscilloscope where the probe are compensated. You can't really disconnect them and try to use them elsewhere and hope that the probe will still be compensated.

Personally I would do the same experience with a signal generator and a oscilloscope and a 50\$\Omega\$ termination between the signal and the probe.

Yep understood and it was just an initial experiment to get some preliminary results comparing apples with apples using the standard 500 MHz probe as the reference (0dB).

3.2 GHz sig gen sweeps are next however we can only rely on its output flatness for accuracy as I don't yet have a $ $ level sensor. 
Maybe tonight as have some paint to get on outside before forecast rain arrives.

Yeah you could let the sig gen sweep slowly and but the oscilloscope in FFT max hold. That would probably do the trick.

But that means I can only FFT them one at a time whereas I'd like to display all 4 together and if I drop the 100 MHz probe and keep the 500 MHz Siglent probe displayed and connect all 4 of them to BNC Tees using their probe tip to BNC adapters we might have a chance of displaying their -3dB points however on a scope only one set of cursors are available.

No worries slowing the sig gen sweep and even syncing it to the scope however just a well timed punch of Stop can serve the same purpose. 
Some painting will give time to think about some clever plan............

Your current setup with the spectrum analyzer would work for RF probes (that use 50\$\Omega\$ input) but you would still need to terminate the signal coming out of the tracking gen and probe at the termination.

Yep, got a couple of good 50 Ohm 1 GHz rated BNC terminators.

[Kosmic]

I guess those probes are normal oscilloscope probes and require a 1M\$\Omega\$ input. Not 50 like the input of your Spectrum analyzer. The impedance problem might explain the waves we are seeing. Hard to draw any conclusion from your experiment. Normally you should see a nice slope going down as frequency increase. The waves are not a good sign.

Also probes compensation is only valid on the oscilloscope where the probe are compensated. You can't really disconnect them and try to use them elsewhere and hope that the probe will still be compensated.

Personally I would do the same experience with a signal generator and a oscilloscope and a 50\$\Omega\$ termination between the signal and the probe.

Yep understood and it was just an initial experiment to get some preliminary results comparing apples with apples using the standard 500 MHz probe as the reference (0dB).

3.2 GHz sig gen sweeps are next however we can only rely on its output flatness for accuracy as I don't yet have a $ $ level sensor. 
Maybe tonight as have some paint to get on outside before forecast rain arrives.

Yeah you could let the sig gen sweep slowly and but the oscilloscope in FFT max hold. That would probably do the trick.

But that means I can only FFT them one at a time whereas I'd like to display all 4 together and if I drop the 100 MHz probe and keep the 500 MHz Siglent probe displayed and connect all 4 of them to BNC Tees using their probe tip to BNC adapters we might have a chance of displaying their -3dB points however on a scope only one set of cursors are available.

No worries slowing the sig gen sweep and even syncing it to the scope however just a well timed punch of Stop can serve the same purpose. 
Some painting will give time to think about some clever plan............

Your current setup with the spectrum analyzer would work for RF probes (that use 50\$\Omega\$ input) but you would still need to terminate the signal coming out of the tracking gen and probe at the termination.

Yep, got a couple of good 50 Ohm 1 GHz rated BNC terminators.

I wouldn't connect them to the source at the same time. If on of them is loading the source or causing reflection it will impact all the results at the same time. Ideally you should test them individually get the data out of the oscilloscope and agglomerate the results on your computer.

[Kosmic]

Hey, anybody know if the rejuvenator functionality, on those CRT tester, is really working or it's a gimmick ?

[med6753]

Hey, anybody know if the rejuvenator functionality, on those CRT tester, is really working or it's a gimmick ?

They did work in extending CRT life. I'm not sure of the complete process but it did involve zapping the CRT momentarily with a higher voltage. But if the CRT was too far gone the results were very marginal.   

[mnementh]

Yup. Used to get regular work from the arcades back in the day; principle is simple: overdrive the heater a little for a short period, apply a HF signal to the cathode while it is boiling from the overdrive, this strips a microscopic layer off and get you good emissivity again. It is as much art as science; getting all 3 guns within 10-20% without smoking one of them takes some practice.

Yes, it is a somewhat destructive process; but the CRT is already toast, so why not.    My experience was that specific units at the arcade would last 1-3 years after a zap; that's a machine that runs 12-14 hour days 6 days a week. I usually was able to zap a CRT at least twice before the gain was insufficient to balance the guns; then you know who they called to do the CRT replacement. Ka-chinnng!

mnem
 

[mnementh]

Ok OCXO all done and installed.      Link to repo with documentation, BOM, gerbers and stuff is on the picture

This is about the first time I've put something together and it worked first time 

      

Looking nice. Gonna use that repo as the base for my own build; mine arrived today. Haven't had time or energy to do more than open & look; but from what I can see, I can say with pretty high confidence that these oscillators are being removed from the scrap boards not with a band or scroll saw, but rather are being excised from the PCB using plunge-cuts with a whizz-grinder.
Not that I would have ever committed such a crime... not me...

I'd say either a Dremel with a big cutoff wheel (maybe a diamond disc) or something like the one above. The way the burr curls on both sides of the board and the direction of the scoring are pretty indicative.

As to whether this is better or worse than the vibration from a bandsaw... I'll say yes, generally much less aggressive vibration. The fact that components are cut through rather than shattered off the board evidence that.

Of course, the pings and dings in the can of the device also evidence the fact that the scrap boards are not exactly handled with greatest of care before the part is excised. Just thought I'd pass that along, in case it affects someone's decision on whether to pull the trigger or not.

mnem
 

[Cubdriver]

Ok OCXO all done and installed.      Link to repo with documentation, BOM, gerbers and stuff is on the picture

This is about the first time I've put something together and it worked first time 

      

Looking nice. Gonna use that repo as the base for my own build; mine arrived today. Haven't had time or energy to do more than open & look; but from what I can see, I can say with pretty high confidence that these oscillators are being removed from the scrap boards not with a band or scroll saw, but rather are being excised from the PCB using plunge-cuts with a whizz-grinder.
Not that I would have ever committed such a crime... not me...

I'd say either a Dremel with a big cutoff wheel (maybe a diamond disc) or something like the one above. The way the burr curls on both sides of the board and the direction of the scoring are pretty indicative.

As to whether this is better or worse than the vibration from a bandsaw... I'll say yes, generally much less aggressive vibration. The fact that components are cut through rather than shattered off the board evidence that.

Of course, the pings and dings in the can of the device also evidence the fact that the scrap boards are not exactly handled with greatest of care before the part is excised. Just thought I'd pass that along, in case it affects someone's decision on whether to pull the trigger or not.

mnem
 

Huh.  Mine arrived today as well; I splurged and bought a lot of ten of them.  They sent 11.  Interestingly, the place I got them from dismounted them - they were shipped in some anti static foam.





I'm not complaining - the furry lab assistants knocked my desoldering iron off the bench recently and the tip has gone missing.  I need to order a new one; that's the best way to be sure the old one will turn up again.

(Also included was a plastic pill thingie that turns out to be a collapsible pen.)




-Pat

[mnementh]

In Other News...

Spent the afternoon flogging the boi to help me finish a task I've been dreading and putting off for weeks now: emptying both sheds, and rotating bikes/lawnmower out from the back to the front and snowblower into the back. Now it is orificially spring, says I.  Well, it will be once wifey washes all our great coats & parkas so I can pack them and our winter boots in a storage bin. 

And my son thought I was gonna let him off the hook with just a dumbbell workout today. 

mnem
*toddles off to a well earned respite*

[vk6zgo]

Yup. Used to get regular work from the arcades back in the day; principle is simple: overdrive the heater a little for a short period, apply a HF signal to the cathode while it is boiling from the overdrive, this strips a microscopic layer off and get you good emissivity again. It is as much art as science; getting all 3 guns within 10-20% without smoking one of them takes some practice.

Yes, it is a somewhat destructive process; but the CRT is already toast, so why not.    My experience was that specific units at the arcade would last 1-3 years after a zap; that's a machine that runs 12-14 hour days 6 days a week. I usually was able to zap a CRT at least twice before the gain was insufficient to balance the guns; then you know who they called to do the CRT replacement. Ka-chinnng!

mnem
 

They had one at the TV Studio where I worked, & I often used it to get a bit  of extra life from some of the less critical pix monitor CRTs.

For some reason, "delta gun" tubes didn't do as well with it as Trinitrons  & the various other variants, like "Linytrons", etc.

We usually only got one rejuvenation out of each tube, as towards the end of life, there was usually one gun that just wouldn't come up.

BW tubes were much more forgiving, but, eventually they started showing massive gamma errors.

There was a very good local regunning facility.
It didn't look much, but the proprietor did an excellent job with Trinitrons, wth results indisinguishable from a new tube.
Again, the "delta gun"tubes were a lot harder to get right.

It was normally not our practice to use regunned tubes in critical monitors, but during a period of financial stress, we (unofficially) relaxed that rule, with good results.

I developed a lot of expertise on pix monitors which I neither desired or anticipated, being mainly employed as a Transmitter Tech!

[mansaxel]

In the context of outsouring, I'd like to point at this lecture-turned-blogpost. Bert Hubert is a quite interesting person, and he's most of the time taking pains to look at things from several different directions. Fair and balanced, in the non-Murdoch (ie. correct) sense.  He refers to a Boeing paper that I've downloaded and am putting on the reading list.

Also: Am ogling oscillators. You bleeping enablers there!

[BU508A]

In the context of outsouring, I'd like to point at this lecture-turned-blogpost. Bert Hubert is a quite interesting person, and he's most of the time taking pains to look at things from several different directions. Fair and balanced, in the non-Murdoch (ie. correct) sense.  He refers to a Boeing paper that I've downloaded and am putting on the reading list.

Also: Am ogling oscillators. You bleeping enablers there!

Me? I didn't say anything!   

[Specmaster]

The 3 leg tant's are made for low impedance, not being reversable. Unless it has more then 25V DC on it I'd let it stay where it is.

Oh OK, thanks. Don't understand though why they don't just put two regular 2-leggeds ones in parallel then ?
3 legged on is a tiny bit more compact, but it's not an issue on that particular board.

It's for installation, not impedance. If you wanted impedance you'd use a tant and ceramic in parallel.

Specs are same as the two legged ones.

Says so on the datasheet! https://www.vishay.com/docs/40044/299d.pdf



Really this is about making them even more of a bastard to get out of a board 

Well I stand corrected. I have only ever seen these used on boards that also had conventional tantalums. The 3 legged ones were in locations that appeared to be EMI/EMC critical. This was on boards from two different OEMs and both had more conventional tants than 3 legged.
Clearly they were marketed for reversability (but not bipolar) but equally clear is that they will also have lower installed series inductance than a two legged one. Thus designers may have selected them for that. Only the designer knows for sure.
With RF it is not uncommon to test specific components of the same nominal value for their specif high frequency properties.
 

I like the idea of having 3 legs, it does eliminate the possibility of them being installed reversed. I just wonder if they were designed in the first place to make PCB assembly easier and quicker because there was no need to look at the device to correctly orientate it before insertion on the board, manually or automated?

[AVGresponding]

Hey, anybody know if the rejuvenator functionality, on those CRT tester, is really working or it's a gimmick ?

They did work in extending CRT life. I'm not sure of the complete process but it did involve zapping the CRT momentarily with a higher voltage. But if the CRT was too far gone the results were very marginal.

CRTs don't even work when they are first manufactured, until they are activated using this method. I have been watching a few Vintage TEK Museum vids recently...

[tggzzz]

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.

I went overboard with mine: capacitance multiplier, 723 regulator (since the diode is low noise), and ferrites/caps. I may be able to provide a screenshot later

Screenshots using a Tek 492AP (red) and HP8562B (green). Note the different horizontal scales, but both are 3Hz VBW and 100Hz RBW.

IIRC the capacitance multiplier feeds both the oven and 723, the 723 feeds the oscillator only. The case is diecast ali, and the PSU is an external linear supply.

Thanks for posting that. It is good to have a comparison. Mine is not miles away but is detectably noisier on the DC-DC. So I set up to do some more investigation. I separated out the DC-DC board and arranged some Molex  0.1" plugs so I can swap supplies around. First test is oven disconnected and oscillator and EFC (+_5V) supply run from a external linear +_ 15V  supply. No detetable noise on the output with DC-DC running or not, or with it loaded with a power resistor.
I then connected ONE side of the oven circuit (which is isolated from the oscillator) to the -15V output of the DC-DC converter. This produced noticable noise on the output which increased when the converter output was loaded. Connecting both sides of the heater to the converter increased the noise significatly. Connecting the DC-DC output common to chassis (the designed configuration) improved things but noise is still there. Adding capcitors across the supply or to ground makes little or no difference. Series inductance made it worse and even connecting the heater circuit via a 47pF series capacitor gave the same noise on the output.
Investigation with a current probe  (Tek P6019) showed bursts of high frequency noise repeating at about 250kHz rate (approx switching freq).
Twas getting late so as a quick check I stuck a couple of bolt in feed-through capacitors in holes in the side frame and fed the heater circuit through those. This seems to fix the noise on the output but I need to investigate further.
Capacitor lead length DOES matter.

If you are looking for PSU switching noise (or other microcontroller hash) then it would be prudent to look at spans up to, say 200kHz.

I've seen +-32/64kHz noise elsewhere using the same 8562:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2446014/?topicseen#msg2446014
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2471700/#msg2471700