Test Equipment Anonymous (TEA) group therapy thread

[bitseeker]

Just an observation as an outsider the the USA there is very little Test Gear on Evilbay as a % coming from the East Coast and in particularly the NE 

Interesting. I have noticed that most TE that I see on eBay listings seem to be from Florida, Texas, and California, which makes sense due to the amount of R&D. I would've expected a lot from North Carolina (i.e., Research Triangle), but haven't noticed much from that state.

Is it a lack of Bulk Sellers, lack of industry or a tightass thing that sees Craigslist being used? 

I'm not aware of a lot of tech & government R&D in the NE area. Maybe they fly under the radar.

I occasionally get a good deal on Craigslist, but most of the time the pricing is the same as (and sometimes higher than) eBay.

The best thing about Craigslist, though, is getting to meet like-minded folks in the area. Many were retired and some were moving out of state.

[mnementh]

Custom-Fabricated Blower for Tek 2465

I've been quietly accumulating an assortment of of 75-80mm fans of various depths and types; going to do a "Hack 'em all, let  God Sort 'em out" shootout.

Looking for ideas on some valid means of comparison-testing their effectiveness... haven't even arrived at a methodology yet. Maybe some kind of homebrew anemometer stuck to an airbox box around the U800 vent?

Doubtful any of them could pull more than a few mm H₂O vacuum... even the OEM one, of which I have an excellent example in just-refurbished condition for baseline testing.

Please, let me know what y'all know of that I could might build as a test rig,

mnem
*cogitating-ily*

Only real Measure for these sort of fans is flow rate in a given duct area. Flow calculated from airspeed meter sitting in that duct either a heater or fan type. I have had a small handheld for years from my R/C glider flying and scoredstole this far more accurate industrial one for looking at Coffee Roaster airflow eBay auction: #303122786600

   So you create this sort of thing

Even if your fan doesn't cover the entire duct can be mathematically fudged by looking at the likely airspeed distribution across the duct as the result of skin friction (second year Fluid Mechanics) but that is OTT. Might be some applicable reading here I just found https://www.cedengineering.com/userfiles/How%20to%20Size%20and%20Design%20Ducts.pdf

Yeah, I'm aware. I learned much of this in HVAC classes when I was a teenager, and again in Tech college for cooling solutions design. have one of the cheapie anemometers bought from Banggood years ago... from the vent at U800, it wouldn't even budge the vanes on my working 2465. Gonna need something a bit more sensitive; probably something not using a magnetic sensor.

The problem here is NOT measuring the fan... we already know what CFM the replacement fans in question are rated at. What we need is a measure of the flow in situ. That's the only way we can make a meaningful comparison against the original fan, especially once I start hacking the fans to make them fit... or to compare something like the one I modded against the original.

   Manual Here

This Mastech MS6252A seems to be a quantum level better on all fronts than my little cheapie though; its impeller is easily twice the diameter, so the meager airflow from that vent may have enough leverage to actually move the thing.

It's rated down to FT/Sec ranges with 2 decimal points as well modes for for CFM. Mine has no volume scales and only goes down to M/sec with 1 decimal point; I remember being very disappointed in mine as it appeared to be more for sailing and surfing than HVAC, which was what I wanted it for. This MasTech appears to be intended for HVAC work... Hmmm...

Theoretically wouldn't the best measure of their effectiveness be how well they do their job? That meaning that temperature could show you directly how they stack up. 

I don't know, maybe I'm missing something or maybe I'm an idiot. Yeah..  I'm probably an idiot.

Well, we have multiple things we're testing for here; with temperature-controlled variants vs non-temperature-controlled models in the mix, so just "temperature" is not necessarily a good yardstick. Where do you measure that temperature? What is a passing grade? For units that exceed the need, what other pros and cons matter?

For example, compare two identical blowers: One thermo-controlled and one running ballz to the wallz all the time; the latter will always run cooler. That doesn't mean it necessarily does a better job; it'll also be making the most possible noise all the time too, which is a consideration for SOME users. Evidently noise was a consideration for the engineers at Tek; they designed the original blower with temp control. Or perhaps, their intent was to make the scope equalize temperature quickly so it could be "warmed up and stable" as soon as possible after power-up.

What I'm trying to do is evaluate a number of commonly available fans of different type and features for a complicated rubrik that boils down to BEST SUITABILITY AS A REPLACEMENT for the fan in the 2465. I'll be using the stock blower and my "severely modded server fan" blower as the yardstick; but maximum airflow in situ compared against a stock 2465 is only the most basic go/no-go minimum standard for suitability. Subjects that don't pass that grade will be dropped with extreme prejudice.

Other important metrics will be Cost, Easily Available, Effectiveness, Quiet vs Thermal Control, and especially Assache Factor in terms of how aggressively they'll need to be hacked in order to use them in the application; my modded server fan will probably be "worst case scenario" assache-wise since it essentially required my weird hand-fabbing skillset and freehand lathe work to make it happen. 

Argue your limitations and they're yours.

Here's a starting point. With the old fan I did a temperature measurement on the back plate. Ambient temp was 74 F. I had the thermocouple in place for several hours and the temp never exceeded 97 F.

You mean the back aluminum plate of the chassis, where the fan, IEC socket, etc pass through?

*added to my test data*


mnem
*fighting a sudden surge of tool-dwagon acquisitiveness*

[worsthorse]

Just an observation as an outsider the the USA there is very little Test Gear on Evilbay as a % coming from the East Coast and in particularly the NE 

Interesting. I have noticed that most TE that I see on eBay listings seem to be from Florida, Texas, and California, which makes sense due to the amount of R&D. I would've expected a lot from North Carolina (i.e., Research Triangle), but haven't noticed much from that state.

Is it a lack of Bulk Sellers, lack of industry or a tightass thing that sees Craigslist being used? 

I'm not aware of a lot of tech & government R&D in the NE area. Maybe they fly under the radar.

I occasionally get a good deal on Craigslist, but most of the time the pricing is the same as (and sometimes higher than) eBay.

The best thing about Craigslist, though, is getting to meet like-minded folks in the area. Many were retired and some were moving out of state.

I've noticed an ebay effect over the last couple of years, at least at hamfests and on CL. There's far less difference in pricing than there used to be. That said, the "don't want to take it home again" factor helps generate hamfest bargains.

Three or four months ago I posted two ads on CL, one "WTB NOS components" and the other "WTB test gear from the 80s and 90s".   It is has been an interesting experience. I met two or three really interesting old timers (which means really old as I am sixty  ), gotten some good deals on parts and gear, and encountered more than one crazy human being.  All in all it has been fun.

One ham traded me a box full of semiconductors for two old Hammarlund receivers. Among all the Ge transistors I ended up with, there were piles of awesome RF power transistors. Another gave me access to his four decades of semiconductor and other parts and basically charged me the same prices he paid oh-so-long ago.  And one of the two garage stashes I've worked on came from one of those ads, too.   

Then there was the guy with about ten thousand parts from a TV repair shop that apparently closed in 1978...   

[tautech]

Great thinking out loud mnem and a perfect summary of all that needs be considered.

This need NOT be overlooked :

Evidently noise was a consideration for the engineers at Tek; they designed the original blower with temp control. Or perhaps, their intent was to make the scope equalize temperature quickly so it could be "warmed up and stable" as soon as possible after power-up.

[beanflying]

SNIPIOUS MAXIMUS....

*added to my test data*


mnem
*fighting a sudden surge of tool-dwagon acquisitiveness*

Your alternate then is then to measure CFM using your meter in free air / open duct to minimise friction losses and then measure it insitu on the scope and associated losses. No need to do any maths on it other than an intake speed comparison it will clearly show which can punch more air using airspeed.

Edit Try measuring using a coupler to your meter of some sort on the intake side not the outlet vents.

[0culus]

Looking at probes for my 7A26 vertical amp, and come across this: eBay auction: #201563096004 Looks good till you examine the probe tip in the photos. 

[beanflying]

SNIPIOUS MAXIMUS....

*added to my test data*


mnem
*fighting a sudden surge of tool-dwagon acquisitiveness*

Two minute model for you and me when mine gets here. Easy to adjust upper and or lower diameter and height (single dimension change for each) Tape the flange bit to the meter.

Fusion file is in the Zip.

[mnementh]

   Manual Here   This Mastech MS6252A seems to be a quantum level better on all fronts than my little cheapie though; its impeller is easily twice the diameter, so the meager airflow from that vent may have enough leverage to actually move the thing.  SNIPIOUS MAXIMUS....

*added to my test data*

mnem
*fighting a sudden surge of tool-dwagon acquisitiveness*

Your alternate then is then to measure CFM using your meter in free air / open duct to minimise friction losses and then measure it insitu on the scope and associated losses. No need to do any maths on it other than an intake speed comparison it will clearly show which can punch more air using airspeed.

Edit Try measuring using a coupler to your meter of some sort on the intake side not the outlet vents.

Yeah; the vent I was measuring at IS an intake vent; this thing pulls all its circulated air out the back of the scope through a single 55mm hole in the rear "firewall". One crucial part of the rubrik, unfortunately, will be "with unmodified stock 2465 cover installed"; as we don't want to be pulling a med booty fab and "customizing with a chainsaw". That was kindof what ignited this project in the first place. 

This means I will need to find some way to measure airflow from those vents... my original choice was the vent right under the unobtanium (and supposedly failure-prone in the case of blower failure) U800 chip. But there ARE other, larger vents that may be better suited... or *Light dawns*  I COULD make a big box and seal the entire bottom of the scope against it.  THAT should get me enough airflow for a valid measurement!

What do you think of that MasTech Anemometer above? Does its specs appear similar to your nice, expensive one? At least in the same ball park?

mnem
Well that was a brief, one-sided fight. I found one on fleaBay listed as "Like New In Box" for $28 with 4-day Free Shipping.

[beanflying]

The Specs on the one I am getting are here. http://www.spectroscopic.com/Airflow/LCA6000va_airflow.pdf They can actually be Calibrated to a standard and are very accurate compared to the Chinese cheapies.

What the cheapies were always good for getting an idea of airspeed for us as we raised or lowered ballast in the gliders based partly on that ground figure. The bigger vaned Mastech should be better than the pocket ones. What I have been using or an older version of eBay auction: #181817310248 notice in the specs resolution is claimed but NEVER accuracy 

[med6753]

Here's a starting point. With the old fan I did a temperature measurement on the back plate. Ambient temp was 74 F. I had the thermocouple in place for several hours and the temp never exceeded 97 F.

You mean the back aluminum plate of the chassis, where the fan, IEC socket, etc pass through?

*added to my test data*


mnem
*fighting a sudden surge of tool-dwagon acquisitiveness*

Yes. Just to the right of the fan where the Inverter/Regulator boards butt up against the back plate.

[bd139]

I was looking at FET probes on Ebay and holy crap.  Are these things made of gold? And it appears that half of them are missing their probe tips.  What's going on here? The probe monster eating them? But I'll bet a lot, if not most, are blown out due to excess voltage. 

Probably just wishful thinking?

I wonder if it's possible to make one with decent response? 

That's exactly what I was wondering while reading the preceding sentences. There probably are projects out there to do it. Bd139 could probably whip something up straight from his junk box.

http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%208.pdf

Page 12

You can hit ~200MHz easily with 2n4416 up front and some >1GHz fT transistors further down the stage.

Tek use 2n4416 albeit selected and matched in some of their FET probes.

[mnementh]

SNIPIOUS MAXIMUS....

*added to my test data*


mnem
*fighting a sudden surge of tool-dwagon acquisitiveness*

Two minute model for you and me when mine gets here. Easy to adjust upper and or lower diameter and height (single dimension change for each) Tape the flange bit to the meter.

   Fusion file is in the Zip.

That's great, especially for that one you just stole!   *Snurrrch!*

I was already thinking, before I even started, to calculate the air volume based on that 55mm opening in the rear firewall. Realizing I needed the stock rear cover in place for valid comparison stuck a big poleaxe through that idea. 

However, the MasTech has a CFM mode, calculated against a diameter you enter. I think if I do the sealed box thing, then cut a hole the right size for the venturi ring to seal against, I'll be able to do an apples-to-apples comparison against the stock blower no matter WHAT fan or blower I have on the back. Plus I can do idling and warmed up airflow against my working 2465 without having to open her up, and then do min/max airflow with stock blower idling/thermistor jumpered to MAX on my parts mule. And I can keep all the modded fans in/about the parts mule as well. 

The Specs on the one I am getting are here. http://www.spectroscopic.com/Airflow/LCA6000va_airflow.pdf They can actually be Calibrated to a standard and are very accurate compared to the Chinese cheapies.

   What the cheapies were always good for getting an idea of airspeed for us as we raised or lowered ballast in the gliders based partly on that ground figure. The bigger vaned Mastech should be better than the pocket ones. What I have been using or an older version of eBay auction: #181817310248 notice in the specs resolution is claimed but NEVER accuracy 

Yeah, that is EXACTLY the one I have, only mine is yellow. The Mastech has full specs in the manual I linked above; they don't sound fabulous but at least they're there. Supposedly, it also can be calibrated.

Lessee... Resolution 0.01 in all scales, accuracy +/- 2% plus 5-50 char...? I'd hazard a guess that means real accuracy of 2% of scale, +/- half the last decimal.     Funny, anything over 100K/H is "For Reference Only"  Still, should be plenty accurate enough for a comparative analysis.

Fuck... I just realized... I've spent over $50 on this experiment already, between blowers and that anemometer. And that's not counting the Dell Server fan, which while technically was "free" salvage, is still a $25-ish name-brand part, even used. And I'm probably gonna chop up another one before I'm done. 

mnem
*Stupid Human Tricks*

[worsthorse]

I was looking at FET probes on Ebay and holy crap.  Are these things made of gold? And it appears that half of them are missing their probe tips.  What's going on here? The probe monster eating them? But I'll bet a lot, if not most, are blown out due to excess voltage. 

Probably just wishful thinking?

I wonder if it's possible to make one with decent response? 

That's exactly what I was wondering while reading the preceding sentences. There probably are projects out there to do it. Bd139 could probably whip something up straight from his junk box.

http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%208.pdf

Page 12

You can hit ~200MHz easily with 2n4416 up front and some >1GHz fT transistors further down the stage.

Tek use 2n4416 albeit selected and matched in some of their FET probes.

Going through the old Tektronix Concepts series on scope probes, both the measurement book and the probe design book, might give you some good ideas...

[mnementh]

...Bd139 could probably whip something up straight from his junk box.

http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%208.pdf   Page 12

You can hit ~200MHz easily with 2n4416 up front and some >1GHz fT transistors further down the stage.

Tek use 2n4416 albeit selected and matched in some of their FET probes.

Going through the old Tektronix Concepts series on scope probes, both the measurement book and the probe design book, might give you some good effing dangerous ideas...

There... fixed that for ya. 

mnem
Not without my Probulator.

[0culus]

Scored a couple of P6106A probes new in the package for decent prices, to go with my 7A26 vertical. 

[tautech]

I was looking at FET probes on Ebay and holy crap.  Are these things made of gold? And it appears that half of them are missing their probe tips.  What's going on here? The probe monster eating them? But I'll bet a lot, if not most, are blown out due to excess voltage. 

Probably just wishful thinking?

I wonder if it's possible to make one with decent response? 

That's exactly what I was wondering while reading the preceding sentences. There probably are projects out there to do it. Bd139 could probably whip something up straight from his junk box.

http://www.introni.it/pdf/Bob%20Pease%20Lab%20Notes%20Part%208.pdf

Page 12

You can hit ~200MHz easily with 2n4416 up front and some >1GHz fT transistors further down the stage.

Tek use 2n4416 albeit selected and matched in some of their FET probes.

Going through the old Tektronix Concepts series on scope probes, both the measurement book and the probe design book, might give you some good ideas...

Yep. 
P47
Tek probe circuits pdf
http://w140.com/tekwiki/images/6/62/062-1146-00.pdf

[mnementh]

*Hands tautech a fire extinguisher then turns around and leaves*

mnem
If ya can't beat 'em, at least put the fires out before they take the whole house.

[tautech]

*Hands tautech a fire extinguisher then turns around and leaves*

mnem
If ya can't beat 'em, at least put the fires out before they take the whole house.

What, scared Bean might find this ^^ ?

[beanflying]

*Hands tautech a fire extinguisher then turns around and leaves*

mnem
If ya can't beat 'em, at least put the fires out before they take the whole house.

What, scared Bean might find this ^^ ?

I am quite capable of making my own fires and sparks without help from Tek and in case of to much cheek Jessie the sneerer will be around to bite people on their bits 

[0culus]

Just don't knock over your Jacob's ladder like ElectroBoom did. 

[bd139]

A friend of mine built one of them back at university in halls. It used an old TV transformer and fly back and multiplier. Made one hell of a racket and blew the breakers for the entire block at least twice. We found out quickly that this extracted the female members of the block rapidly when the lights went out. Unfortunately the moment they found out that we frequented the electrical engineering course they ran a mile 

What course do you do? Err, err, err social sciences! 

Edit: arm hardly in pain at all now so off to Andover. Fingers crossed for some TE. Only grabbing one handed stuff today if there is any. No boat anchors

[beanflying]

Please note ALL TEA items in the shack are not even plugged in let alone powered up. 

Much nicer than the horror I hacked up when I first got the NST. Sliding adjustment works well without tools, fairly narrow top Arc but it is cool at about 12 C in the shack. Time to repaint the NST to match the improved upper end.

https://youtu.be/VCIXY-z27EM

[0culus]

So fedex cocked up delivering my HP 1727 storage scope. Shows delivered, but I was home all day and never saw a fedex truck or heard a knock. 

[Ero-Shan]

It would me too [emoji849], for clarity I was of course referring to 7150s. I know that they are very slow and have limited features compared to a 34401, but I quite like them. One thi g I find infuriating about them is that regardless of the resistance value, be it ohms, K or M, it only reads as K grrr. [emoji102]

Sent from my POT-LX1 using Tapatalk

I might need that mule myself. Don't expect to get all 5 of them working fine. Sacrificing the worst could allow 4 running fine.

With a clean bench and no important household chores to do, checking them out looks like something for tomorrow.

The cables in them are bastards, very stiff and could do with a little slack on them to allow them to sit flat when you unclip the top board and pivot it away to allow access to the shield and the the bottom power board. To make it worse they are not plug and socketed either, take care.

Sent from my POT-LX1 using Tapatalk

Maybe it is different for your 'plus' models, but I consider it one of the rather easier to disassemble devices. Yes, the cables are somewhat stiff (and the 2 fasteners on the shield did not easily open!). Except for the guard wire, however, the cable(s) from the front terminals are plugged.



I also like the rich colors 



But these red solid nylon 'hinges' are awfully stiff. Pulling the shield up to get at the transformer screws was nasty.



I also had trouble getting the backlight LEDs out. They're sitting rather tight in the diffuser plastic. The traces on the PCB are very thin (there's absolutely no reason for them to be such). During unsoldering some traces+pads lifted off. 

Mine is not as evenly lit as yours, but it is infinitely better than before. I could even consider using one now. 
It's not done yet, however. The value shown is from my cheap AD584 reference, and a sticker said 'AC out of tolerance'. (The 34401 in the back shows the same 10 volts.)
Resistance looks very good though, it's likely within tolerance. I agree that giving all as 'KΩ' (the capital 'K' is also wrong, they reused the 'V' there) is not a good idea.



Of course there were 3 dead caps, but replacing them apparently changed nothing. 2 of the feet were missing. Those adhesive rubber feet tend to stick to the bench or device under more than were they're attached to.  As I had a perfectly matching new set, I replaced them.

When using it without the case (first picture, but DSKY attached), the logic board sometimes made a slightly buzzing sound. That sound could be changed by pressing lightly on the right side of the board. It was not the Schaffner filter () and not the transformer. I still have no idea where it might have come from.

[bd139]

Got tek 2235A    edit: good condition. May explode knowing my luck. Will thoroughly inspect it and test it first.

Edit: also got an HP attenuators switch box. Don’t need it but it has a full complement of feet and was only £2