Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Yeah, I know... that's kindof what I was getting at. I think Robert mentioned that unit.

Then comes the question... is it really better, or just shinier and more gewgaws? What is the standard by which THIS one is validated...? A known-good analog 432A with a calibrated digital meter plugged into it? Are the "current" analog 432As Keysight offers REALLY new production, or just NOS HP product kept around because of their value (when paired with mount and thermistor) as a transfer standard?

This scenario reminds me of the calibration procedures in the manual for the Tek 2465... one of the specified instruments is a calibrated 2465. 

mnem
 

[0culus]

Yeah, I know... that's kindof what I was getting at. I think Robert mentioned that unit.

Then comes the question... is it really better, or just shinier and more gewgaws? What is the standard by which THIS one is validated...? A known-good analog 432A with a calibrated digital meter plugged into it? Are the "current" analog 432As Keysight offers REALLY new production, or just NOS HP product kept around because of their value (when paired with mount and thermistor) as a transfer standard?

This scenario reminds me of the calibration procedures in the manual for the Tek 2465... one of the specified instruments is a calibrated 2465. 

mnem
 

Well, it has a digital display instead of a swinging needle. If you consider that a plus. 

As Robert pointed out, the beauty of the thermistor mount is that since the thermistor bridge is dc balanced, you basically need a dc voltage standard (which any primary standards lab worth their salt will have) in order to calibrate the thermistor mount, as I understand it. There's really nothing more to it. It's rather simple and elegant, which is probably why it has enduring popularity. Contrast this to open loop style meters (436A, 437, 438, etc) that use the 84xx sensors. These meters all have a precision power reference to calibrate the sensor; the 432A/N432A need no such thing.

[mnementh]

Yeah, that I can totally get... there is very little marketing involved in the production of the sensor heads or the thermistor mount; they're not very exciting. The meter itself is where marketing comes in, so every once in a while a more modern-looking model has to happen.

Where I got on the wrong side of this conversation was the prehistoric analog meter still being kept in stock at HPAK; that's what I was originally talking about, not the thermistor/mount as a separate entity (even tho, as I understand it, the mount and thermistor can actually be used by themselves).

I still suspect the old meter lingers there because TPTB know there is/are some large money customer(s) (be it military, manufacturing, scientific or calibration labs) that still have some need for that particular model. And I still suspect that reason is some standards document (maybe internal, maybe external) that is ultimately referred to again and again in which that meter is a requisite. Or maybe they keep it around because it is used to calibrate/validate subsequent models, and they have enough NOS to be able to offer some for sale to calibration labs etc, I dunno. 

But it makes no sense for them to spend the money keeping track of the damn things for 5+ decades if someone who makes these decisions didn't expect to recoup it from somewhere; I mean, FFS, the things outlived that crazy bitch and the HP television years...

mnem
 

[0culus]

I checked in the 2001 Agilent catalog (the latest one I have), and the original 432A was definitely still available for sale then. Based on the case design of the N432A, I'd say that dates from the Agilent years itself, sometime after 2001.

I got really lucky with mine...I bought a 432A + 478A thermistor combo on ebay VERY cheap, expecting it to be broken or wonky but it turned out to work perfectly (which is why I decided against dropping $1200 with Keysight to go over the 478A). As far as I can tell, it's pretty damn accurate. I also have the 8477A calibrator box for the 432A meter, which gives me confidence that the meter itself works and is in-spec. I also have the 11683A Range Calibrator which does the same thing, for the open loop meters (I have a pair of 438A meters).

[med6753]

Yeah, that I can totally get... there is very little marketing involved in the production of the sensor heads or the thermistor mount; they're not very exciting. The meter itself is where marketing comes in, so every once in a while a more modern-looking model has to happen.

Where I got on the wrong side of this conversation was the prehistoric analog meter still being kept in stock at HPAK; that's what I was originally talking about, not the thermistor/mount as a separate entity (even tho, as I understand it, the mount and thermistor can actually be used by themselves).

I still suspect the old meter lingers there because TPTB know there is/are some large money customer(s) (be it military, manufacturing, scientific or calibration labs) that still have some need for that particular model. And I still suspect that reason is some standards document (maybe internal, maybe external) that is ultimately referred to again and again in which that meter is a requisite. Or maybe they keep it around because it is used to calibrate/validate subsequent models, and they have enough NOS to be able to offer some for sale to calibration labs etc, I dunno. 

But it makes no sense for them to spend the money keeping track of the damn things for 5+ decades if someone who makes these decisions didn't expect to recoup it from somewhere; I mean, FFS, the things outlived that crazy bitch and the HP television years...

mnem
 

Analog meters still have their place. They are much easier to use and much more accurate in making fine adjustments such as when aligning RF gear than a digital bargraph or display. Much easier to spot peaks and trends. Any RF tech worth his salt will have analog meters on hand including the lowly VTVM.   

[med6753]

Long distance traveler. 

Over the years this GR to female BNC adapter had made it's way to OZ eventually being owned by Bean. Apparently Bean sent it to Tautech in NZ along with some other items. When Tautech heard that I was looking for one he graciously sent it to me. And here it is. It has come full circle. It has a lot of miles on it but it's still good. 

I now have a complete set of adapters thanks to Tautech.   

[tautech]

Long distance traveler. 

Over the years this GR to female BNC adapter had made it's way to OZ eventually being owned by Bean. Apparently Bean sent it to Tautech in NZ along with some other items. When Tautech heard that I was looking for one he graciously sent it to me. And here it is. It has come full circle. It has a lot of miles on it but it's still good. 

I now have a complete set of adapters thanks to Tautech.   

[Zoli]

...
Snip
...
This scenario reminds me of the calibration procedures in the manual for the Tek 2465... one of the specified instruments is a calibrated 2465. 

mnem
 

Classic:
To understand recursivity, first you have to understand recursivity.

[Saskia]

@mansaxel
The guy I got the Metra Hits from has a 3rd that I tried to buy, but he won't sell. He said he still needs it in case one of his customers needs him to fix something.

If he changes his mind I'll let you know.
@ch did you already take possession of yours ? Last time I checked a neighbor has signed for it.

[Saskia]

About to pick up 2 speakers, Quadral Altan. The woofers need to be refurbished, hopefully the tweeters are ok. Those are ribbon tweeters, also in use in Quadral Titan and Vulkan, and worth a fortune.

I don't want to part out the Altans, but it never hurts to have some spares.

If everything else is ok, bringing them back to life will cost about 150€ (done professionally). An unprofessional botch job could probably had for about 40, but I am willing to invest.

Already loaded up the car to go up north. Will have a week off, most likely won't discord tonite
(Hit the road, Jane, ...)

[Robert763]

I missed most of the 478A /432A discussion, I went to bed early. Most has been said already but in summary:

It's the head (475A) that is important not the meter. The meter just need to balance the thermistor bridge, an external digital meter makes the measurement in the metrology set-up

No, there is nothing else that makes an easy, portable RF power transfer standard. All you have to ship is the head. The 432x does not have to be calibrated and the DVM/DMM you use with it is just local calibration.

The new N432A was built because hey culd not get parts to keep making the 432A. They could have just done a bridge balancing box for use with an external DMM but thet would not have required calibration so less through life revenue for Keysight. To be fair it does do he calculations for you so is easier to use.

The calibration reference for them is another thermal device, probably a fluid based calorimeter system.

The military / aviation "you must use an ACME 123ABC meter" is different. Often it is just a contempory standard meter that could be replaced by something else. The trouble is you don't know for sure unless the manual says "or similar". Ive said before that failure to use the specified test equipment on a angle of attack vane was one of the factors in the Lion Air 737MAX crash. I've personally seen a case where my favorite DMM Fluke 8060A was called up and the workshop was using an 89IV this gave different results. Trouble was it was fine on the bench with either but in the "corner-case" (low, slow, hot / high, fast cold etc) where it really mattered the instrument would misread if set with a 89IV. The voltage being measured was a kHz range badly distorted sinewave. The only other meters that worked were thermal ones like HP3404 or Fluke 8920
And there we are back at thermal 

[mansaxel]

@mansaxel
The guy I got the Metra Hits from has a 3rd that I tried to buy, but he won't sell. He said he still needs it in case one of his customers needs him to fix something.

If he changes his mind I'll let you know.
@ch did you already take possession of yours ? Last time I checked a neighbor has signed for it.

I'm sort of (never will be fully) sated with Gossen gear; I have a MetraHit 25S coming hopefully Tuesday. It's sitting somewhere in a DB Schenker representative (i.e. typically a supermarket; they run parcel front-ends at their tobacco/gambling counters; our local COOP is a front for PostMord and DB Schenker) out-container, waiting to be picked up by the lorry. It was registered as submitted to the DB Schenker representative Thursday evening, so with my luck it's being picked up by the lorry Monday afternoon and then loaded on another one early next morning to be booked in at our COOP Tuesday. (which isn't hard, based on the data I've got, the seller is 50km from me, I could have walked there faster) 

I'd be fine with all that if the seller hadn't dragged their ass.

The auction closed October 4th.
Evening 6th the freight was booked.
Evening 8th it was submitted to representative.
With luck, I'm getting it 13th.

For a 50km ride. Not impressed.

[bd139]

Minor gripe here: default Kicad footprints are shit. Just spent two hours designing several footprints that aren't rubbish 

[BU508A]

I'm sort of (never will be fully) sated with Gossen gear;
[...]

Hei Mans, have you checked out the ebay Kleinanzeigen in Germany for Gossen gear?

Here are some examples:






                        

[Specmaster]

Yep, totally agree, I remember when I tried it I found that some footprints didn’t look right either and bore zero resemblance to the actual item so I gave up, didn’t have time to attempt learning how to correct them.

[tonyalbus]

On the bench a Scope SA... i remember seeing one here, only a few weeks ago, think it was med or bd ?
i got interested because of his pictures here in TEA and i found one...
good deal because it was from one of my viewers who wanted to see it on my channel...
so both of us happy....



[edit] typo's

[BU508A]

Yep, totally agree, I remember when I tried it I found that some footprints didn’t look right either and bore zero resemblance to the actual item so I gave up, didn’t have time to attempt learning how to correct them.

Congratulations! This was your posting #10000!     

[bd139]

Yep, totally agree, I remember when I tried it I found that some footprints didn’t look right either and bore zero resemblance to the actual item so I gave up, didn’t have time to attempt learning how to correct them.

Yeah I'm just redesigning them from scratch rather than correcting. Focusing on reasonable pad sizes for hand soldering, single/double sided boards without PTH, toner transfer, 0.1 grid system and my standard parts library.

Test rig - bit of stripboard underneath it

[Specmaster]

Yep, totally agree, I remember when I tried it I found that some footprints didn’t look right either and bore zero resemblance to the actual item so I gave up, didn’t have time to attempt learning how to correct them.

Congratulations! This was your posting #10000!     

Well, I never noticed, thanks for pointing it out, that's a milestone that won't be repeated for sure 

[med6753]

Not sure if I'll be on Discord later today. Going to start painting this morning and if I'm at a point where I can stop I'll be on. You don't fully realize how much crap you have until you have to move it. 

[factory]

On the bench a Scope SA... i remember seeing one here, only a few weeks ago, think it was med or bd ?
i got interested because of his pictures here in TEA and i found one...
good deal because it was from one of my viewers who wanted to see it on my channel...
so both of us happy....



[edit] typo's

Would that be BD? Who had that Radcom SA that I'm sure he said on here he was going to keep, well it appeared & went on ePay.
I wonder if he did anything with the unfinished one from the UK vintage radio forum.
https://www.vintage-radio.net/forum/showthread.php?t=170561

David

[factory]

Ok found a unicorn on ebay. It's a very complicated and broken unicorn with three legs and half a horn but I'll fix that on arrival if no one else finds the auction or is less cheap than me. 

Very complicated, broken & a unicorn in the UK, wouldn't be something like a HP 5360A computing counter would it?

David

[BU508A]

You mean this thing here?

[tonyalbus]

You mean this thing here?

super cool.....

[Cerebus]

But it makes no sense for them to spend the money keeping track of the damn things for 5+ decades if someone who makes these decisions didn't expect to recoup it from somewhere; I mean, FFS, the things outlived that crazy bitch and the HP television years...

mnem
 

Why would they bother to keep manufacturing it (the sensor)? Well, why not if it is good enough and there's a demand? It's surely more expensive to cut a new design and qualify that than to "keep track" as you put it, of an old design. This is all custom manufacture, there's no parts obsolescence to deal with.

The metering bit has been replaced (in 2011), 432A obsoleted and the N432A substituted for it.

RF power measurements aren't particularly high precision or high accuracy by their nature, that they're typically measured and specified on a dB scale gives a clue to that - so an analogue meter is probably always going to be 'good enough'.  There's no driving need for a new shiny more accurate or more precise meter - except perhaps the perception by some that a 'digital' meter is somehow more accurate than an 'analogue' one. The need to make automated measurements that one obviously can't with an analogue device would be a sane requirement, and that seems to have now been taken care of with the retirement of the 432A and the introduction of the new shiny digital N432A. The accuracy of the new shiny digital version is 0.1% ±5uW, which makes the 6¹/₂ digit ADC on it ever so slightly overkill. I suspect that the fact that it looks like one of the TrueVolt DVM range is no accident, but without schematics I can't prove my suspicion that it's a 34461 DVM with the input circuitry ripped out and replaced with interfacing to the power sensor.

As to the core measurement technology - a thermistor oven and a balancing bridge. That's probably going to be good enough for its purposes forever. The thermistor bit is easily characterised against primary standards. The bridge as a measurement technique is good enough that it's still being used as the core of measurement of some primary standards to stupid levels of precision.