Test Equipment Anonymous (TEA) group therapy thread

[Robert763]

Recently on ebay:

Code: [Select]

10x 0.1R      0.1%   Burster Type 1168
10x 1R        0.1%   Burster Type 1168
10x 10R       0.05%  Burster Type 1166
10x 100R      0.02%  Burster Type 1164
10x 1000R     0.02%  Burster Type 1164
10x 10000R    0.02%  Burster Type 1164
10x 100000R   0.02%  Burster Type 1164


Today arrival:

Have not decided yet, if I'll built a resistor decade box or if I'll make some resistor calibration sets.
What do you think?

Cal boxes. Also pick the best MATCHED three and arrange the binding posts so you can use as a Hamon divider.

Seems a shame if they cut up a complete decade box and sold those individually, certainly looks that way.   

David

I was told by the seller, that they were part of a Pt100 calibrator.
Not sure, why he removed them but I think, he wanted all the high precision resistors in them.
He is selling some more of these type of resistors but with very special values.

https://www.ebay.com/itm/133726996530
https://www.ebay.com/itm/402792461991
https://www.ebay.com/itm/402792471654
https://www.ebay.com/itm/133727010002
https://www.ebay.com/itm/402792347941
https://www.ebay.com/itm/133726915387

If you look at the photos you will see the resistors are marked with the corresponding Pt100 temperature.

[Bad_Driver]

Yes PSU ripple had crossed my mind however the main amp PSU seems to be working fine as it's still driving the 5 speakers without hum or noticeable distortion and able to blast us out of a 4 car garage when Pink Floyd get played and you crank it right up ! 

So check how the lower voltage auxiliary supplies are generated. Might be a separate winding (with failed bridge rectifier) or some nasty dropper resistors from main amp voltage causing local hot spots on the PCB and nearby components failing ...

Yep all simple stuff you would normally spot with a little experience....spose I should go looking for a SM....oh hang on I've already got one on my Manual folder ! 

If it's a single sided board, check for broken solder joints. Mechanical or thermal stress makes them unreliable.

Yeah they generally are SS with lots of bare jumper wires however I'd rather not pull the PCB unless I need to.
It's one of them rainy day jobs when there's not much else on which is hardly ever !

Hi Tautech

send me an PM with valid E-Mail, I have the service manual by the hand but it is too large for posting if you still need it.

B.D.

[VK5RC]

What you need is an OLD power meter, a 432Aplus 478A sensor, preferrably with option H76. While the sensor is old it allows DC balance and low frequency subsitution. he meter does not have to be in cal just the sensor and a DMM.
This is the standrd for calibrating the calibrators and most sensors.

Thanks Robert. Yes indeed that is what is shown in the power calibration procedure. Now I have an excuse to go back to Ebay. 

A while ago my 3458's AC card died and I was able to source a fair price repaired card, the Calibration procedure required 2 very expensive AC to DC converters, but you could work around it by using a good AC source. My 33519b was the best I had, so I gave it a go - I nearly fell over when I later sent it to HP for calibration and it passed.
I think you can get a pretty good idea by comparing your gear with each other - it soon stands out if one is 'off' 👍
(What am I saying - this is a TEA site) you of course need more gear to help the two clocks problem 😁

[tautech]

Yes PSU ripple had crossed my mind however the main amp PSU seems to be working fine as it's still driving the 5 speakers without hum or noticeable distortion and able to blast us out of a 4 car garage when Pink Floyd get played and you crank it right up ! 

So check how the lower voltage auxiliary supplies are generated. Might be a separate winding (with failed bridge rectifier) or some nasty dropper resistors from main amp voltage causing local hot spots on the PCB and nearby components failing ...

Yep all simple stuff you would normally spot with a little experience....spose I should go looking for a SM....oh hang on I've already got one on my Manual folder ! 

If it's a single sided board, check for broken solder joints. Mechanical or thermal stress makes them unreliable.

Yeah they generally are SS with lots of bare jumper wires however I'd rather not pull the PCB unless I need to.
It's one of them rainy day jobs when there's not much else on which is hardly ever !

Hi Tautech

send me an PM with valid E-Mail, I have the service manual by the hand but it is too large for posting if you still need it.

B.D.

Thanks very much but I have it already the user manual and SM in 2 parts, the SM and schematic which I attach for those following.
The SM is 5.8 MB so too large to post here.

[Robert763]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

[Specmaster]

Yes PSU ripple had crossed my mind however the main amp PSU seems to be working fine as it's still driving the 5 speakers without hum or noticeable distortion and able to blast us out of a 4 car garage when Pink Floyd get played and you crank it right up ! 

So check how the lower voltage auxiliary supplies are generated. Might be a separate winding (with failed bridge rectifier) or some nasty dropper resistors from main amp voltage causing local hot spots on the PCB and nearby components failing ...

Yep all simple stuff you would normally spot with a little experience....spose I should go looking for a SM....oh hang on I've already got one on my Manual folder ! 

Myself, I'd search out which relay(s) is/are rattling first. May not even be in the protection circuit; some of the older models used relays in the input switching and/or had relays that provided impedance matching or put the speakers in series if you switched in an additional pair of speakers on the B channel.

mnem
 

A, B and Rear all working fine and I think Robert might be correct in that the rattler is an AV input but not showing on the display. 
Bad Driver seems to know these units well so will roll with what he's offered.

Within 30min the relay started randomly rattling again but after cycling the input buttons some it seems gone ! 
Will keep an eye/ear on it. 

In that case it is looking more and more like its got some high impedance in the relay circuit and input switches could certainly do that, ie., use a single pole switch to control a double pole relay to switch in and out of an input circuit for instance.

[med6753]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

You're right. From those pictures it appears the be a round CRT and the front bezel is a separate plastic piece. Therefore no trace rotation and as you stated loosen rear CRT clamp and rotate the entire CRT. It also appears to be a plastic case rather than metal which means every time you move the scope any stray magnetic field and even the Earth's magnetic field will cause the trace to tilt.

That is just like the cheap plastic case Heathkit scopes from the 1970's. I speak from experience.   

[tautech]

Yes PSU ripple had crossed my mind however the main amp PSU seems to be working fine as it's still driving the 5 speakers without hum or noticeable distortion and able to blast us out of a 4 car garage when Pink Floyd get played and you crank it right up ! 

So check how the lower voltage auxiliary supplies are generated. Might be a separate winding (with failed bridge rectifier) or some nasty dropper resistors from main amp voltage causing local hot spots on the PCB and nearby components failing ...

Yep all simple stuff you would normally spot with a little experience....spose I should go looking for a SM....oh hang on I've already got one on my Manual folder ! 

Myself, I'd search out which relay(s) is/are rattling first. May not even be in the protection circuit; some of the older models used relays in the input switching and/or had relays that provided impedance matching or put the speakers in series if you switched in an additional pair of speakers on the B channel.

mnem
 

A, B and Rear all working fine and I think Robert might be correct in that the rattler is an AV input but not showing on the display. 
Bad Driver seems to know these units well so will roll with what he's offered.

Within 30min the relay started randomly rattling again but after cycling the input buttons some it seems gone ! 
Will keep an eye/ear on it. 

In that case it is looking more and more like its got some high impedance in the relay circuit and input switches could certainly do that, ie., use a single pole switch to control a double pole relay to switch in and out of an input circuit for instance.

Still comes and goes despite cycling the inputs so I think it needs the covers off and a clean inside at least and customary checks of the PSU/s and inspection of the PCB for dry joints etc......but another day as time for some Z's. 

[xrunner]

The trouble is that the thermistor mounts are insanely expensive and sensitive.  I have a 432A -- less thermistor mount -- that I'm sort of thinking that I'll try to build something for. Just for the fun of it.

A secondary source for the 6-pin connector would be a great start. Relatively inexpensive thermistors are available. And no, I do not expect this to be precise or sensitive like the original, just proof of concept.

Well mansaxel, I was really referring to the internal 50 MHz calibration source for now. The sensor I purchased is supplied with a current calibration with all the paperwork and documentation. If I got another meter and that internal cal source (power output) compared closely to the one I have now (even using the way I was checking the first one), I'd be more confident that these sources are very stable over time. But if it didn't ... well ... yea I understand that r-hole.

 

*Raises hand*

Acknowledging ...

A while ago my 3458's AC card died and I was able to source a fair price repaired card, the Calibration procedure required 2 very expensive AC to DC converters, but you could work around it by using a good AC source. My 33519b was the best I had, so I gave it a go - I nearly fell over when I later sent it to HP for calibration and it passed.
I think you can get a pretty good idea by comparing your gear with each other - it soon stands out if one is 'off' 👍
(What am I saying - this is a TEA site) you of course need more gear to help the two clocks problem 😁

Right! That's the TEA spirit! 

The sensor is supposed to be delivered today. These shipping companies are so overloaded they deliver more and more on Sundays now. The other day I got a package delivered in the evening. The truck that pulled up was a green Enterprise rental truck. The man that got out was dressed in Brown. My brain alerted on that sight -

 *** color mismatch ***

He looked rather beat-down to me. I just made the comment "Enterprise rental? Is UPS out of trucks?"

He said "We have been for a while. You wouldn't believe it, it's all crazy."

[Robert763]

Bit more time nuttery. When I got the HP OCXO from storage I also grabbed one of my Efratom FRK Rubidium atomic standards. Rigged it up on Thursday night on a bench supply. Current draw was normal and after about half an hour the lock indicaor came on and it was rock steady compared to a HP GPSDO. Was fine when I went to bed but Friday morning the lock light was out and the control voltge sweeping. It was going through 10MHz so not a crystal oscillator problem. The Rb bulb was lit but lamp voltage was low. Next step wass checking lamp housing temperature (113 +_ 2 deg C). While doing this with a themocouple there was a flash and all went dead.  Not sure wht the probe touched but the input fuse blew. 
The foam insulation is also breaking down. Next task is to replace fuse and foam and start again.
Need to find some foam first.

More importantly, we have a new addition to the home, a rescue dog. She is a German Shepherd / Siberian Huskey cross. Very nevous and a bit underweight she will be taking priority over TEA activities for a while.

[mnementh]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

You're right. From those pictures it appears the be a round CRT and the front bezel is a separate plastic piece. Therefore no trace rotation and as you stated loosen rear CRT clamp and rotate the entire CRT. It also appears to be a plastic case rather than metal which means every time you move the scope any stray magnetic field and even the Earth's magnetic field will cause the trace to tilt.

That is just like the cheap plastic case Heathkit scopes from the 1970's. I speak from experience. 

Nope. Look again; the CRT is square, that's just a bit of em/electrostatic shielding around the neck that is conical.

mnem
 

[BU508A]

Nice Marconi power meter, together with two power sensors.
And it has a calibration output.

https://www.ebay-kleinanzeigen.de/s-anzeige/marconi-6960b-rf-power-meter-2-sensoren/1735899701-168-24602

[xrunner]

Nice Marconi power meter, together with two power sensors.
And it has a calibration output.

https://www.ebay-kleinanzeigen.de/s-anzeige/marconi-6960b-rf-power-meter-2-sensoren/1735899701-168-24602

Do you want encouragement? 

Interesting that they have the same (as hp) 50 MHz 0.0 dBm cal output. I'm wondering how that choice came about historically ...

[mnementh]

WAG: Probably a "middle ground" frequency that both this generation and the previous generation of resistance-based sensors could be cal'd against; thereby providing a calibration chain that continues back to the dark ages. Or maybe the components inside the sensor were something new and only available from one manufacturer at the time they started making the solid-state variants...

mnem
 

[Robert763]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

You're right. From those pictures it appears the be a round CRT and the front bezel is a separate plastic piece. Therefore no trace rotation and as you stated loosen rear CRT clamp and rotate the entire CRT. It also appears to be a plastic case rather than metal which means every time you move the scope any stray magnetic field and even the Earth's magnetic field will cause the trace to tilt.

That is just like the cheap plastic case Heathkit scopes from the 1970's. I speak from experience. 

Nope. Look again; the CRT is square, that's just a bit of em/electrostatic shielding around the neck that is conical.

mnem
 

Interesting, It may vary with production, the 710D here:
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710d.html
Has a round CRT. 
The picture Vegata posted in Reply #88500 has no model marking on the front and looks more like the radiomuseum's photo o a 710D than ther one of a 710C.
It also looks like a round CRT from the picture posted (corners cut off same as radiomuseum 710D) 

[factory]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

And trace align, scale, or trace rot controls are also used with round tubes with internal graticule, as used in hp 130C, 140A, 175A etc.

David

[med6753]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

You're right. From those pictures it appears the be a round CRT and the front bezel is a separate plastic piece. Therefore no trace rotation and as you stated loosen rear CRT clamp and rotate the entire CRT. It also appears to be a plastic case rather than metal which means every time you move the scope any stray magnetic field and even the Earth's magnetic field will cause the trace to tilt.

That is just like the cheap plastic case Heathkit scopes from the 1970's. I speak from experience. 

Nope. Look again; the CRT is square, that's just a bit of em/electrostatic shielding around the neck that is conical.

mnem
 

Well, hard to tell from that pix but if it is I do not see any trace rotation wires going to a coil near the face plate. It would then be almost impossible to correct trace tilt because obviously you can't rotate a rectangular CRT.   

[Robert763]

Nice Marconi power meter, together with two power sensors.
And it has a calibration output.

https://www.ebay-kleinanzeigen.de/s-anzeige/marconi-6960b-rf-power-meter-2-sensoren/1735899701-168-24602

Do you want encouragement? 

Interesting that they have the same (as hp) 50 MHz 0.0 dBm cal output. I'm wondering how that choice came about historically ...

Well as the whole dBm scale is based on 1mW (0dBm) and these meters operate in the milliwatt range its an obvious choice. For the microwatt sensors HP suppled a 30dB attenuator with the sensor.

[mnementh]

Yeah, actually we haven't seen the one Vegeta is looking at; the one in Reply #88500 was just a random pic I found to put the thing into perspective for the sake of discussion. Yes, he said 710C; but then we get into the all-too-common problem of whether the person selling the thing even knows what they have...

But it makes sense; it's pretty obvious these were contract manufactured for ITT, and had either cost or performance constraints that drove the differences between models.

mnem
 

[xrunner]

Well as the whole dBm scale is based on 1mW (0dBm) and these meters operate in the milliwatt range its an obvious choice. For the microwatt sensors HP suppled a 30dB attenuator with the sensor.

What about the choice of 50 MHz?

[Robert763]

dunno if you like this scope or not xD

anyway, the one they offered has its traces slightly inclined, not perfectly horizontal. I suppose there is a knob from behind to adjust this? kindly check it if you have the scope or know about it,.

There should be a "trace rotation" control either on the rear panel or inside the case to make the traces horizontal.

I don't think there is a control on this 'Scope.  It's a simple matter of loosing the clamp on the back of the tube and rotating the whole tube. The controls are normally only used with rectangular tube.
You can see the shiny clamp on the tube in photos here
https://www.radiomuseum.org/r/metrix_oscilloscope_ox_710c.html

Manuals are online

You're right. From those pictures it appears the be a round CRT and the front bezel is a separate plastic piece. Therefore no trace rotation and as you stated loosen rear CRT clamp and rotate the entire CRT. It also appears to be a plastic case rather than metal which means every time you move the scope any stray magnetic field and even the Earth's magnetic field will cause the trace to tilt.

That is just like the cheap plastic case Heathkit scopes from the 1970's. I speak from experience. 

Nope. Look again; the CRT is square, that's just a bit of em/electrostatic shielding around the neck that is conical.

mnem
 

Well, hard to tell from that pix but if it is I do not see any trace rotation wires going to a coil near the face plate. It would then be almost impossible to correct trace tilt because obviously you can't rotate a rectangular CRT.

There are red and yellow wires that appear to be going into the rear of the magnetic shield that don't seem to be in the picture of the 710D. These could be trace rotation.

[Robert763]

Well as the whole dBm scale is based on 1mW (0dBm) and these meters operate in the milliwatt range its an obvious choice. For the microwatt sensors HP suppled a 30dB attenuator with the sensor.

What about the choice of 50 MHz?

Practically it's a compromise of being low enough to calibrate without worring about high frequency mismatch and connection loss issues but high enough to not be affected by the DC blocking capacitor in some sensors.
Might also have been specified in some NIST or military standard.

[mnementh]

Next on this morning's installment of "Things that make you go Hmmmmmm..."

mnem
 

[xrunner]

I'm like the kid that keeps asking "why" every time I get an answer. 

Yea your probably right Robert, thanks.

[bd139]

Well as the whole dBm scale is based on 1mW (0dBm) and these meters operate in the milliwatt range its an obvious choice. For the microwatt sensors HP suppled a 30dB attenuator with the sensor.

What about the choice of 50 MHz?

Practcally it's a compromise of being low enough to calibrate without worring about high frequency mismatch and connection loss issues but high enough to not be affected by the DC blocking capacitor in some sensors.
Might also have been specified in some NIST or military standard.

If I remember correctly the actual frequency is "somewhat near 50MHz" on those things. Usually an LC oscillator with amplitude feedback of some sort. Doesn't get much better than that. Regarding the DC blocking capacitor, that. Probably covers the largest amount of power sensors out there.