Test Equipment Anonymous (TEA) group therapy thread

[med6753]

Forgive me...

I seem to have this repeating brain fart where you and Specmaster and bd139 are concerned; I'm always swapping your "specialties" in my memory. I know it's somehow related to my horrible memory for names. It's like that information is written on different sides of the same brain cell, and I never know which side is going to "click" with which identity. EVENTUALLY I usually get it ironed out... But it is sometimes VERY embarrassing until I do. And it's a lot harder when you don't have a face and voice to associate. 

mnem
Doyt!

You are forgiven.  But I'm curious....just what is my "specialty" in the eyes of the group? (Maybe I don't wanna know  ).

Hey, I am terrible with names too. You could tell me your name and 10 minutes later I'd forget it and have to ask again. But for some reason my mind tends to be a "bear trap" for trivial and useless stuff that I could remember 10 years later. I got so much crap floating around up there that I think sometimes it's gonna overflow and spill out.     

[URI]

Noob question.

On pictures on the net, I can see on the back (rear) of the HP 5385A is four screw holes.  Did they make rear (bottom) feet for these?

All devices that came in this type of housing have those screw holes. Yes, for bottom feet.
But if even the pictures in the service manual show the back of the 5385A without bottom feet I doubt they were factory-equipped with any.

Nevertheless, this is not true for my 5006A signature analyser: With the same housing like the 5385A mine came with bottom feet that are also clearly shown in that manual.   

[URI]

I'm eagerly awaiting the arrival of my latest acquisition, another Tek TDS210, not that I need another but it comes with a differential probe, something I have been looking for at a sensible price.

Wow, isn't that probe worth more than the scope? Nice score.

Yeah, if the probe's salvageable, I'm afraid he may be getting The Jammy back before it ever even officially goes to URI... 

Or -depending on the order of the arrival of our scopes the Jammy Git award will be switched between us high speed..      

Edit: BTW, that's a very nice score indeed, specmaster!   
Am loosely looking for one also, but there was no offer that seemed low enough to me yet. So: searching goes on.

[mnementh]

Noob question.

On pictures on the net, I can see on the back (rear) of the HP 5385A is four screw holes.  Did they make rear (bottom) feet for these?

All devices that came in this type of housing have those screw holes. Yes, for bottom feet.
But if even the pictures in the service manual show the back of the 5385A without bottom feet I doubt they were factory-equipped with any.

Nevertheless, this is not true for my 5006A signature analyser: With the same housing like the 5385A mine came with bottom feet that are also clearly shown in that manual.   

Possibly that rear bezel was used for more than one product that had a the same cross-section to the enclosure?

[EDIT] Or is that what you were saying, and I just daftly didn't get it first time around? [/EDIT]

I'm eagerly awaiting the arrival of my latest acquisition, another Tek TDS210, not that I need another but it comes with a differential probe, something I have been looking for at a sensible price.

Wow, isn't that probe worth more than the scope? Nice score.

Yeah, if the probe's salvageable, I'm afraid he may be getting The Jammy back before it ever even officially goes to URI... 

Or -depending on the order of the arrival of our scopes the Jammy Git award will be switched between us high speed..      

If that happens, you'll BOTH have the right tools to measure and quantify the oscillation. I expect screen shots!!! 

mnem
 

[tautech]

I'm eagerly awaiting the arrival of my latest acquisition, another Tek TDS210, not that I need another but it comes with a differential probe, something I have been looking for at a sensible price.

Wow, isn't that probe worth more than the scope? Nice score.

Yeah, if the probe's salvageable, I'm afraid he may be getting The Jammy back before it ever even officially goes to URI... 

Or -depending on the order of the arrival of our scopes the Jammy Git award will be switched between us high speed..      

Still, I reckon it was URI that really scored.
What was your total outlay ?

[mnementh]

Forgive me...

I seem to have this repeating brain fart where you and Specmaster and bd139 are concerned; I'm always swapping your "specialties" in my memory. (SNIP)
mnem
Doyt!

You are forgiven.  But I'm curious....just what is my "specialty" in the eyes of the group? (Maybe I don't wanna know  ).

Hey, I am terrible with names too. You could tell me your name and 10 minutes later I'd forget it and have to ask again. But for some reason my mind tends to be a "bear trap" for trivial and useless stuff that I could remember 10 years later. I got so much crap floating around up there that I think sometimes it's gonna overflow and spill out. 

Well, if I look at your post history to make sure I don't put my foot in my mouth again...

I'd say "Tant-Slayer, Necromancer of Test Equipment, and Agitator-at-Large" ; in no particular order... 

mnem
"When he opens his mouth, it's just to change feet."

[mnementh]

Still, I reckon it was URI that really scored.
What was your total outlay ?

He's waiting to say until he actually has it in his sweaty little hands and has a chance to do a reality check on it, lest he jinx it. I don't blame him one bit. 

mnem
*Toddles off to ded*

[tautech]

Still, I reckon it was URI that really scored.
What was your total outlay ?

He's waiting to say until he actually has it in his sweaty little hands and has a chance to do a reality check on it, lest he jinx it. I don't blame him one bit. 

mnem
*Toddles off to ded*

So sweaty he'll need to be careful he doesn't drop it ! 
......................
Nighty night !

[URI]

Still, I reckon it was URI that really scored.
What was your total outlay ?

He's waiting to say until he actually has it in his sweaty little hands and has a chance to do a reality check on it, lest he jinx it. I don't blame him one bit. 

mnem
*Toddles off to ded*

So sweaty he'll need to be careful he doesn't drop it ! 

Be assured, I'll take very much care of that this will not happen.     

[Ero-Shan]

Hermes finally delivered my packet. When I came home on Thursday I could spot a largish cardboard box under the stairs to my front door right from the street.

As we all know, yours truly loves counters, yet he is sorely lacking in this department (has only about 8 ), especially when it comes to counting above 250 MHz. There his single device is that Kontron, which fell a bit from grace owing to its crappy front plate:



So he was constantly on the lookout for something that would count up to 1 GHz and have a somewhat more professional appearance.

When he saw this, he set his meanness aside temporarily and bid a fair amount. Spending enough money helps winning auctions.

And now he is the proud owner of a decent counter. At least he thinks so.



So far only tested with my GPSDO, where it showed 9.9999967 MHz.

The only thing that's missing are schematics for the A version, 5334B's are readily available (the user's manual covers both, A and B).
As long as it works, there's no real need, however.

Oh, and it actually has its original feet!

[Specmaster]

In Other News...

Looking like the resistance measurement issues with my 3478A are in fact F/R jack switch-related. Cleaning seemed to help; went from fluctuating between .6 ohms and .3 ohms shorted (using banana patch cords, not clips; these measure 0.9 ohm and 0.045 ohm on my Fluke 189 and DE-5000 respectively) down to fluctuating 0.22xx - 0.19xx ohms. After reviewing the schizzmatics, I discovered I could bypass 1/2 of the switch by swapping a couple leads at J107; that dropped shorted resistance to 0.116x - 0.1170 ohms.

Part of me is saying, as I know I'm likely going to really want the rear jacks about twice in my lifetime, that I should just bypass the switch completely and solder the front ports into service; it'll be more accurate and reliable anyways... meanwhile, the purist in me keeps trying to strangle that part.  We'll see who wins after dinner. 

mnem
"There's no rest for the wicked, but the virtuous have no pillows."

That switch was my first and only suspect for the cause and also the only part of the meter that is likely to be dormant for long periods. As such it would allow crud to be building up undected  until someone activated the switch and allowed crud to migrate courtesy of the contact wiper which has some under its wiper. I'd give it another of contact cleaner and give it some beans while operating the switch remove that crud, also I'd try some pure alcohol on it, nothing to lose. [emoji38]

[Specmaster]

Forgive me...

I seem to have this repeating brain fart where you and Specmaster and bd139 are concerned; I'm always swapping your "specialties" in my memory. I know it's somehow related to my horrible memory for names. It's like that information is written on different sides of the same brain cell, and I never know which side is going to "click" with which identity. EVENTUALLY I usually get it ironed out... But it is sometimes VERY embarrassing until I do. And it's a lot harder when you don't have a face and voice to associate. 

mnem
Doyt!

Well I guess it's all over to bd139, then because RF also blows my brain to bits. So it seems as if you haven't had sufficient coffee yet to jump start your brain either[emoji1787][emoji1787][emoji1787]

[Specmaster]

I'm eagerly awaiting the arrival of my latest acquisition, another Tek TDS210, not that I need another but it comes with a differential probe, something I have been looking for at a sensible price.

Wow, isn't that probe worth more than the scope? Nice score.

Well ordinarily yes but this one was incomplete, but I sorted that and it only has a bandwidth of 25MHz. Apart from that it is almost brand new and comes with its own pouch and manual.

[med6753]

Hermes finally delivered my packet. When I came home on Thursday I could spot a largish cardboard box under the stairs to my front door right from the street.

As we all know, yours truly loves counters, yet he is sorely lacking in this department (has only about 8 ), especially when it comes to counting above 250 MHz. There his single device is that Kontron, which fell a bit from grace owing to its crappy front plate:



So he was constantly on the lookout for something that would count up to 1 GHz and have a somewhat more professional appearance.

When he saw this, he set his meanness aside temporarily and bid a fair amount. Spending enough money helps winning auctions.

And now he is the proud owner of a decent counter. At least he thinks so.



So far only tested with my GPSDO, where it showed 9.9999967 MHz.

The only thing that's missing are schematics for the A version, 5334B's are readily available (the user's manual covers both, A and B).
As long as it works, there's no real need, however.

Oh, and it actually has its original feet!

Wow! Nice score! 

[Specmaster]

I'm eagerly awaiting the arrival of my latest acquisition, another Tek TDS210, not that I need another but it comes with a differential probe, something I have been looking for at a sensible price.

Wow, isn't that probe worth more than the scope? Nice score.

Yeah, if the probe's salvageable, I'm afraid he may be getting The Jammy back before it ever even officially goes to URI... 

mnem
 

I'm pleased to say that the probe looks to be new, had the probe leads missing but they are standard shrouded meter leads so that's OK. New battery fitted, switched on, connected to scope and its Working fine, switchable in 3 ranges, 20X, 50X and 200X so I'm a very happy bunny, only downside, it's bandwidth is 25MHz but perfect for audio work[emoji106]

[Specmaster]

I'm eagerly awaiting the arrival of my latest acquisition, another Tek TDS210, not that I need another but it comes with a differential probe, something I have been looking for at a sensible price.

Wow, isn't that probe worth more than the scope? Nice score.

Yeah, if the probe's salvageable, I'm afraid he may be getting The Jammy back before it ever even officially goes to URI... 

Or -depending on the order of the arrival of our scopes the Jammy Git award will be switched between us high speed..      

Still, I reckon it was URI that really scored.
What was your total outlay ?

My total outlay was £165 including postage which at the time I was dubious about as the seller was extremely short on details. Only had the photo, not even showed it switched on so I was kind buying a bit in the dark and relying on my gut instinct. Even that  almost changed when there tremendous problems in the payment for it and I was starting get some very serious bad vibrations about the deal as a whole but that's another story on its own to be told. [emoji6]

[PA0PBZ]

The stated total gain for the unit is +8 dB (it has a pre-amp in it using an MRF 901), but it was actually -10 when I got it. I managed to tweak it up to -1 dB gain while moving the peak response over to 144.730 MHz, but that's all I can get out of it. The transistor is working because if you disconnect power you get barely anything out, but I think it's weak, so I ordered another one to see what happens. Really that's about all I can see that can go wrong, everything else is pretty much intact.

How is the current drain? They say it should be in to 10-25mA range so if you see something different then it's time to blame the transistor. I think your tuning is fine, stated as -28dB for a 600KHz offset @ 150MHz and that is what your plot shows.

[Cerebus]

What makes a transistor have a "weak" gain? I am not an expert in this type of failure analysis but I have seen it before in other repairs I've made.

For BJTs putting too much reverse bias across the base emitter junction, i.e. a voltage in excess of V_ebo with any significant current, can permanently reduce the H_FE (and h_fe) of the transistor. Know as 'zenering' the transistor as the base emitter junction acts like a zener diode in reverse bias. Far too much current and it obviously goes 'pop!'.

It typically happens (for a common emitter amplifier) when the base voltage gets dragged out of spec (often beyond the rails) because of excess system input voltage getting past what, if any, input protection there is.

[Martin.M]

Martin, you have my sympathy and understanding. I have the military version of the Tek 7603N called the OS 245(P)/U. I did find a manual for it but it is missing sections including the Z-Axis and CRT schematics. In fact, I found several sources but it turns out that they apparently are from the SAME master copy. So you would think I could use the manual for the civilian 7603N. Not quite. Tek made so many changes and updates over the life of the 7603 series that it's almost like a different scope on the inside. My scope is an early version and just about all the manuals available are for the later versions. And of course I had a problem with the CRT blanking circuit so I was troubleshooting blind. It can be very frustrating and annoying.     

swap from another Tek the 155-022 and look if there is the problem 

[Ero-Shan]

And when it comes to banana plugs, I have a certain preference for 'Büschelstecker' BÜLA 20 K (maybe because Hirschmann is close to where I live?). The selection of colors is not ideal, but I also have a bunch of red boots.



They do have a failure mode where they get hooked in the jack and you need some force to get them out (already fearing real damage), yet they look totally innocuous. 

[med6753]

Forgive me...

I seem to have this repeating brain fart where you and Specmaster and bd139 are concerned; I'm always swapping your "specialties" in my memory. (SNIP)
mnem
Doyt!

You are forgiven.  But I'm curious....just what is my "specialty" in the eyes of the group? (Maybe I don't wanna know  ).

Hey, I am terrible with names too. You could tell me your name and 10 minutes later I'd forget it and have to ask again. But for some reason my mind tends to be a "bear trap" for trivial and useless stuff that I could remember 10 years later. I got so much crap floating around up there that I think sometimes it's gonna overflow and spill out. 

Well, if I look at your post history to make sure I don't put my foot in my mouth again...

I'd say "Tant-Slayer, Necromancer of Test Equipment, and Agitator-at-Large" ; in no particular order... 

mnem
"When he opens his mouth, it's just to change feet."

Tant-Slayer? With a doubt. I hate the little bastards. 

"Necromancer of Test Equipment"?  There you go with them big words again. I had to look that up. Wizard or Warlock practicing the occult such as raising the dead. OK, I'll buy that. I've brought numerous pieces of test equipment back from the gates of hell and made them useful again. I've also killed my share. Just yesterday through my own carelessness and stupidity I had a fatality. And I'm not gonna say right now what it was and don't ask because I am super pissed at myself. It's gonna go in the DOA (Dead On Arrival) closet to perhaps work on and possibly revive at a later day. But I don't hold out much hope that my future necromancy will work. We'll see.

Agitator-at-large? Absolutely. Never pass up the opportunity to create chaos and watch the hilarity that results. 

[med6753]

Forgive me...

I seem to have this repeating brain fart where you and Specmaster and bd139 are concerned; I'm always swapping your "specialties" in my memory. I know it's somehow related to my horrible memory for names. It's like that information is written on different sides of the same brain cell, and I never know which side is going to "click" with which identity. EVENTUALLY I usually get it ironed out... But it is sometimes VERY embarrassing until I do. And it's a lot harder when you don't have a face and voice to associate. 

mnem
Doyt!

Well I guess it's all over to bd139, then because RF also blows my brain to bits. So it seems as if you haven't had sufficient coffee yet to jump start your brain either[emoji1787][emoji1787][emoji1787]

No, his brain was sleepy. He wrote that sometime after midnight.

[bd139]

Also never assume I know what I’m doing. The amount of smoke and fire that comes out suggests I don’t 

My speciality is, err, fire extinguishing.

[med6753]

My speciality is, err, fire extinguishing.

And blowing up greenhouses. 

[Ero-Shan]

"Necromancer of Test Equipment"?  There you go with them big words again. I had to look that up. Wizard or Warlock practicing the occult such as raising the dead. OK, I'll buy that. I've brought numerous pieces of test equipment back from the gates of hell and made them useful again. I've also killed my share. Just yesterday through my own carelessness and stupidity I had a fatality. And I'm not gonna say right now what it was and don't ask because I am super pissed at myself. It's gonna go in the DOA (Dead On Arrival) closet to perhaps work on and possibly revive at a later day. But I don't hold out much hope that my future necromancy will work. We'll see.

Well, don't ask me! It happens quite often that all goes rather well up to the finishing touches. Then, with just a wee bit of carelessness, I outright kill it (like I did with that LeCroy) with no hope of necromancing (I like that word, got to stash it in my organic dictionary). It's not just that a piece of (again working fine) equipment is lost, also lost is all the time and sweat you invested, which can be substantial.
That's what really makes me angry.