Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 14548114 times)

McBryce, Vince and 31 Guests are viewing this topic.

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 14483
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103425 on: September 26, 2021, 10:20:14 pm »
I did some digging just now because the seller's name looked familiar so I went back through my purchase history and, sure enough, he's there.  Remember those new-old-stock US Navy surplus Agilent 34401A meters that turned up on eBay last year?  It was the same seller who had those so I'm pretty confident buying one of those Flukes.  That's why anainstr looked familiar.

If the Fluke is is as good as the Agilent 34401A they sold me, I'll be quite happy:

Yes, I remember the seller too. This was my first 34401A :D
Now something puzzles me about the eBay GSP: If I prepare a lower offer, the shipping and tax is estimated higher than in the original ad? Can someone shed some light on this?
IIRC, there's a field in the GSP processing forms where the seller can add a fee for their time filling out the form.  ::) Then tax is calculated including that fee.

mnem
 :-/O

I have sold a lot of items via the GSP and over this side of the pond at least the seller has zero access to anything to with the GSP, that is all handled by eBay themselves. The seller just gets paid for the item at what ever price it went for, plus the domestic postage, less eBay fees. The buyer gets the GSP fees added onto the price they have to pay the seller. Seller then only has to send the item to the GSP depot in their country, then GSP do the rest.
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Offline Cubdriver

  • Supporter
  • ****
  • Posts: 4201
  • Country: us
  • Nixie addict
    • Photos of electronic gear
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103426 on: September 26, 2021, 10:22:53 pm »
did some work over the weekend.
Pinball backbox, Fish Tales to be exact.
Sanded it down and went at it with Polyester filler. Brought it back into shape (reconstructed the edges, ...), then sanded, used filler, sanded, .... you get the idea.

Fortunately I had decent equipment that a friend of mine loaned to me:
This:
https://www.festool.de/produkte/holzbau/exzenterschleifer/576329---ets-ec1505-eq-plus
and this:
https://www.festool.de/produkte/saugen/absaugmobile/574983---ctm-36-e-ac-230v
and this:
https://werkzeugstore24.de/festool-ansetzhilfe-ah-es-ets-etsc-205316.html?gclid=Cj0KCQjwtMCKBhDAARIsAG-2Eu_Fz0RHL-wikWUIcOq3jffdTXweHcPAs4BZ0EzG9D5sp1Bbfv3fXvwaAsPiEALw_wcB with the corresponding 125mm sander. Still took about 20 hours to rebuild that box. Next one will be faster ...

The box now has its first primer coating, additional final filler/sander stage will follow. After that it will be decal time, then the old backbox content can be moved.

In other news I just got the ok for a major pinball mayhem.
Will get 3 pinballs for 2000€, a Flintstones, a BS Dracula and a Grand Lizard (?) ...
Given today's pb pricing that is extremely good.

Ahh, yes.  Festool.  Crack for woodworkers.

And congrats on getting the new PB machines.

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 
The following users thanked this post: Saskia

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103427 on: September 26, 2021, 10:29:23 pm »
I have sold a lot of items via the GSP and over this side of the pond at least the seller has zero access to anything to with the GSP, that is all handled by eBay themselves. The seller just gets paid for the item at what ever price it went for, plus the domestic postage, less eBay fees. The buyer gets the GSP fees added onto the price they have to pay the seller. Seller then only has to send the item to the GSP depot in their country, then GSP do the rest.
Ehhh... it was a long time since I sold anything via the GSP and then only I think like a carburetor and some PC parts, but I seem to recall having to fill out usual customs short-form crap; prohibited/hazardous/live/perishable/certain types of plants and country of origin. And, like I said, a fee. Or maybe that was the usual dialog box to add a fee for packing & materials, and I misremembered.  :-//

mnem
*currently nuking the clock*
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Offline Saskia

  • Super Contributor
  • ***
  • Posts: 2893
  • Country: de
  • you unlock this door with the key of imagination
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103428 on: September 26, 2021, 10:43:48 pm »
Oh, I always wanted to be like the silver dragon out of Dragonlance.
But, fantasies are fantasies and life always catches up with you.
 
The following users thanked this post: mnementh

Offline Neomys Sapiens

  • Super Contributor
  • ***
  • Posts: 3268
  • Country: de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103429 on: September 26, 2021, 11:03:24 pm »

Anyway here is the first of the crusty hp relics, the 207A sweep oscillator.


I wouldn't recommend buying T&M gear from Selkies!
 

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 14483
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103430 on: September 26, 2021, 11:05:03 pm »
I have sold a lot of items via the GSP and over this side of the pond at least the seller has zero access to anything to with the GSP, that is all handled by eBay themselves. The seller just gets paid for the item at what ever price it went for, plus the domestic postage, less eBay fees. The buyer gets the GSP fees added onto the price they have to pay the seller. Seller then only has to send the item to the GSP depot in their country, then GSP do the rest.
Ehhh... it was a long time since I sold anything via the GSP and then only I think like a carburetor and some PC parts, but I seem to recall having to fill out usual customs short-form crap; prohibited/hazardous/live/perishable/certain types of plants and country of origin. And, like I said, a fee. Or maybe that was the usual dialog box to add a fee for packing & materials, and I misremembered.  :-//

mnem
*currently nuking the clock*
Well, it could be that you have different rules over there, who knows?
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 
The following users thanked this post: mnementh

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103431 on: September 26, 2021, 11:35:50 pm »
Talking about soldering iron, anybody know if the new T245 JBC Clone are any good ? Supposed to be 200W. I really doubt it.

https://www.aliexpress.com/item/1005002983155657.html   

Edit: Was reviewed over here doesn't look bad.


That's a tough choice there... My gut reaction is that if I were ready to plunk down that kind of money, I'd rather stalk eBay for another MX-500 piecemeal at a reasonable price. But if I were in need right now... I'd probably seriously consider it, especially knowing it will drive a T12 handle if I think the JBC bits suck.

mnem
 :-/O
Yeah, not being able to change the temp is a deal breaker for me. I just ordered one of those. Will see if they are any good.

This just came thru my inbox: https://www.aliexpress.com/item/1005003129484702.html

Not sure what you paid; eMail ad says US$88 for T245 version & it comes up CAD$114 +$35 S/H in my dashboard.

mnem
 :-/O
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Offline Kosmic

  • Super Contributor
  • ***
  • Posts: 2505
  • Country: ca
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103432 on: September 26, 2021, 11:40:15 pm »
Talking about soldering iron, anybody know if the new T245 JBC Clone are any good ? Supposed to be 200W. I really doubt it.

https://www.aliexpress.com/item/1005002983155657.html   

Edit: Was reviewed over here doesn't look bad.


That's a tough choice there... My gut reaction is that if I were ready to plunk down that kind of money, I'd rather stalk eBay for another MX-500 piecemeal at a reasonable price. But if I were in need right now... I'd probably seriously consider it, especially knowing it will drive a T12 handle if I think the JBC bits suck.

mnem
 :-/O
Yeah, not being able to change the temp is a deal breaker for me. I just ordered one of those. Will see if they are any good.

This just came thru my inbox: https://www.aliexpress.com/item/1005003129484702.html

Not sure what you paid; eMail ad says US$88 for T245 version & it comes up CAD$114 +$35 S/H in my dashboard.

mnem
 :-/O

Yeah in ali emails they don't put the real price to generate interest. when you click you have a surprise. Anyway the best price I found is 160$ shipped for the version with the t245 handle.

When I click on your link the total is 175.31$Can
« Last Edit: September 26, 2021, 11:43:26 pm by Kosmic »
 

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103433 on: September 27, 2021, 12:47:10 am »
Oh, sneaky lying bastards. If you accidentally click the voltage first it doesn't change the price and unclicks the voltage when you click the T245 version. There is no combination gets you a T245 version for $114 (which does convert to ~USD$90, though); and the ad clearly does state that price is for the T245 version.





That round of douche-baggery makes me even more inclined to never, ever buy the plucking thing, even if it were the last damned soldering station on earth.

mnem
grrrr... clock-ity douche-ity mumble-grumble grrrr...
« Last Edit: September 27, 2021, 12:51:17 am by mnementh »
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 

Online Vince

  • Super Contributor
  • ***
  • Posts: 4168
  • Country: fr
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103434 on: September 27, 2021, 01:17:14 am »
Well I now have the crusty hp 207A sweep oscillator & 3480B voltmeter from Chelford, didn't go back through Peover Superior this week, instead a detour to Macclesfield to fill the van with more stuff from my Grandparents estate. On the way back the A534 Wheelock bypass got blocked by some mangled vehicles & the police had closed the road, had to turn back & go another way.  |O

Anyway here is the first of the crusty hp relics, the 207A sweep oscillator.


No worries, a quick wipe it will be like new again !   :scared:
 
The following users thanked this post: Neper

Offline cyclin_al

  • Frequent Contributor
  • **
  • Posts: 856
  • Country: ca
  • VE3TSD / VA2XAR
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103435 on: September 27, 2021, 02:36:11 am »
*blerk*  Fluke 8020A DMM for sale:  (for some reason I do not want it)
https://www.kijiji.ca/v-general-electronics/ottawa/fluke-8020b-multimeter/1576997452


For something that is actually interesting, a RM564
https://www.kijiji.ca/v-general-electronics/markham-york-region/tektronix-rm564-vacuum-tube-type-oscilloscope-and-2-extra-module/1585100005
Is this something reasonable for someone (me) who has not worked on one of these before?
I like the idea that it is rack mountable...  might be worth a low-ball offer.
Biggest problem is that it is far away, closer to where the dwagon lives used to live.
« Last Edit: September 27, 2021, 03:17:55 am by cyclin_al »
 

Offline med6753

  • Super Contributor
  • ***
  • Posts: 11313
  • Country: us
  • Tek nut
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103436 on: September 27, 2021, 02:51:39 am »

For something that is actually interesting, a RM564
https://www.kijiji.ca/v-general-electronics/markham-york-region/tektronix-rm564-vacuum-tube-type-oscilloscope-and-2-extra-module/1585100005
Is this something reasonable for someone (me) who has not worked on one of these before?
I like the idea that it is rack mountable...  might be worth a low-ball offer.
Biggest problem is that it is far away, closer to where the dwagon lives used to live.


Well, how familiar are you with working with vacuum tube circuits? Not sure if the RM564 has a vacuum tube PSU or sand state. Could be either depending upon what year it was made. The plug-in's are definitely a hybrid design of hollow state and sand state. They can be difficult if not near impossible to service without a plug-in extender (I have one). Although with the rack mount you might have better access than the bench version. Don't know for sure since I have no rack mount 560 series. And of course the high voltages associated with tube circuits.   
An old gray beard with an attitude.
 

Offline cyclin_al

  • Frequent Contributor
  • **
  • Posts: 856
  • Country: ca
  • VE3TSD / VA2XAR
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103437 on: September 27, 2021, 04:31:22 am »

For something that is actually interesting, a RM564
https://www.kijiji.ca/v-general-electronics/markham-york-region/tektronix-rm564-vacuum-tube-type-oscilloscope-and-2-extra-module/1585100005
Is this something reasonable for someone (me) who has not worked on one of these before?
I like the idea that it is rack mountable...  might be worth a low-ball offer.
Biggest problem is that it is far away, closer to where the dwagon lives used to live.


Well, how familiar are you with working with vacuum tube circuits? Not sure if the RM564 has a vacuum tube PSU or sand state. Could be either depending upon what year it was made. The plug-in's are definitely a hybrid design of hollow state and sand state. They can be difficult if not near impossible to service without a plug-in extender (I have one). Although with the rack mount you might have better access than the bench version. Don't know for sure since I have no rack mount 560 series. And of course the high voltages associated with tube circuits.

Thanks Mike,

The one point that you make that is the big one is vacuum tube circuits.  In all honesty, I am not familiar with working with these.  I know taking on this scope would involve me taking a step up.  Is it reasonable to step up to tubes at the same time as stepping up to a scope like this?

Something like this would be a "reach project"; more of a long-term goal to dream about.
There are a few steps along the way.
First, I need to create a proper lab space suitable for high voltage.  That needs some house renovation to be finished.
There are other people and furry family members about, so need a lab space that is controlled off-limits.
What all the means, is that I am looking at a number of progressions to get there, and it is going to take some time.
I do not expect to jump in and start on it right away.  Even when I do start on it, I do not expect to finish it up quickly.

I am open to suggestions like do a project with scope xyz first to build up skills, or do project xxx with vacuum tubes first.
I also have to decide for myself whether to get this scope now and have to store it while renovation is done, or whether I should hold off until I am ready and see what opportunities are available at that time.
 

Offline mnementh

  • Super Contributor
  • ***
  • Posts: 17541
  • Country: us
  • *Hiding in the Dwagon-Cave*
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103438 on: September 27, 2021, 04:51:08 am »
...Well, middle segment of the middle digit has started to fade and flicker; I figured hey, replace a single LED and live with the fact it'll probably be brighter than the others... worst case, hand soldering 21 0603-ish LEDs.

   

mnem



It's fixed. Dismantling and re-swaging the retainer pegs on the "display module" wasn't too bad, but it did turn into a wee bit of a bodge as I had to steal a 0603 LED from the ALARM location, however I only had a few red ones in all my crap for a replacement ATM.

It just screams "WRONG!!!" out loud at me... tho I'm certain by morning I'll have forgotten all aboot it, since I have my favorite clock back.  :-//

mnem
*knocks self unconscious with a clock mallet* :=\
« Last Edit: September 27, 2021, 05:00:28 am by mnementh »
alt-codes work here:  alt-0128 = €  alt-156 = £  alt-0216 = Ø  alt-225 = ß  alt-230 = µ  alt-234 = Ω  alt-236 = ∞  alt-248 = °
 
The following users thanked this post: med6753, Specmaster, ch_scr, cyclin_al, BILLPOD, Neper

Offline mansaxel

  • Super Contributor
  • ***
  • Posts: 3554
  • Country: se
  • SA0XLR
    • My very static home page
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103439 on: September 27, 2021, 05:18:45 am »

For something that is actually interesting, a RM564
https://www.kijiji.ca/v-general-electronics/markham-york-region/tektronix-rm564-vacuum-tube-type-oscilloscope-and-2-extra-module/1585100005
Is this something reasonable for someone (me) who has not worked on one of these before?
I like the idea that it is rack mountable...  might be worth a low-ball offer.
Biggest problem is that it is far away, closer to where the dwagon lives used to live.


Well, how familiar are you with working with vacuum tube circuits? Not sure if the RM564 has a vacuum tube PSU or sand state. Could be either depending upon what year it was made. The plug-in's are definitely a hybrid design of hollow state and sand state. They can be difficult if not near impossible to service without a plug-in extender (I have one). Although with the rack mount you might have better access than the bench version. Don't know for sure since I have no rack mount 560 series. And of course the high voltages associated with tube circuits.

Thanks Mike,

The one point that you make that is the big one is vacuum tube circuits.  In all honesty, I am not familiar with working with these.  I know taking on this scope would involve me taking a step up.  Is it reasonable to step up to tubes at the same time as stepping up to a scope like this?

Something like this would be a "reach project"; more of a long-term goal to dream about.
There are a few steps along the way.
First, I need to create a proper lab space suitable for high voltage.  That needs some house renovation to be finished.
There are other people and furry family members about, so need a lab space that is controlled off-limits.
What all the means, is that I am looking at a number of progressions to get there, and it is going to take some time.
I do not expect to jump in and start on it right away.  Even when I do start on it, I do not expect to finish it up quickly.

I am open to suggestions like do a project with scope xyz first to build up skills, or do project xxx with vacuum tubes first.
I also have to decide for myself whether to get this scope now and have to store it while renovation is done, or whether I should hold off until I am ready and see what opportunities are available at that time.

Watch a few guitar amp repair videos, and once you pick your jaw off the floor from being flabbergasted at the cargo cult, you'll realise that valve technology is not that complicated. It's more like deceptively simple...

To elaborate; I have not taken on any scopes, but I've been lightly fixing and recapping a few VTVM and my 428. Of course they're simpler (the 428 is fairly complex though) and the voltage is something you need to consider, but apart from that, with documentation, it's pretty straightforward.

Clear though, is that I have a soft spot for rack mount gear, and you need to save that scope from the toob vultures!!

Offline med6753

  • Super Contributor
  • ***
  • Posts: 11313
  • Country: us
  • Tek nut
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103440 on: September 27, 2021, 05:19:53 am »


Thanks Mike,

The one point that you make that is the big one is vacuum tube circuits.  In all honesty, I am not familiar with working with these.  I know taking on this scope would involve me taking a step up.  Is it reasonable to step up to tubes at the same time as stepping up to a scope like this?

Something like this would be a "reach project"; more of a long-term goal to dream about.
There are a few steps along the way.
First, I need to create a proper lab space suitable for high voltage.  That needs some house renovation to be finished.
There are other people and furry family members about, so need a lab space that is controlled off-limits.
What all the means, is that I am looking at a number of progressions to get there, and it is going to take some time.
I do not expect to jump in and start on it right away.  Even when I do start on it, I do not expect to finish it up quickly.

I am open to suggestions like do a project with scope xyz first to build up skills, or do project xxx with vacuum tubes first.
I also have to decide for myself whether to get this scope now and have to store it while renovation is done, or whether I should hold off until I am ready and see what opportunities are available at that time.

If you want to learn vacuum tube theory and operation I'm sure there's plenty of resources here on the net that can give you some basics. Start with the diode then work your way up to a triode and then eventually to a pentode. When I went to college they were still teaching vacuum tube theory first and then went into solid state. And prior to that as a teen almost everything I worked on was tubes. Transistors were the scary bug-a-boo.  :-DD

I would start simple. A great simple starting point would be a VTVM. They generally have a dual diode tube and a dual triode tube. And best of all it's useful in the lab. That 564 would probably overwhelm you, especially with the plug-in's. And as I mentioned you should have a plug-in extender. They do show up on Ebay once in a while and a quick check shows one for 560 series for the stupid price of $50.00 USD. IMHO that's robbery.

You absolutely need a safe and secure lab when working on VT equipment to keep curious hands and paws away. The voltages involved are no joke.  :o :scared:


 

An old gray beard with an attitude.
 
The following users thanked this post: mnementh, cyclin_al

Offline capt bullshot

  • Super Contributor
  • ***
  • Posts: 3033
  • Country: de
    • Mostly useless stuff, but nice to have: wunderkis.de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103441 on: September 27, 2021, 05:55:38 am »



It's fixed. Dismantling and re-swaging the retainer pegs on the "display module" wasn't too bad, but it did turn into a wee bit of a bodge as I had to steal a 0603 LED from the ALARM location, however I only had a few red ones in all my crap for a replacement ATM.

It just screams "WRONG!!!" out loud at me... tho I'm certain by morning I'll have forgotten all aboot it, since I have my favorite clock back.  :-//


Good job, the evironment will thank you for saving one more consumer item from being prematurely dumped! I like this spirit.
Yes, there's one "WRONG!!!" with it, it's got a blue display. Such thing would never make it's way into my ambience. Especially for an alarm clock to be used in the bed room, nothing but a gently glowing red LED display is acceptable.
« Last Edit: September 27, 2021, 06:04:53 am by capt bullshot »
Safety devices hinder evolution
 
The following users thanked this post: mnementh

Offline capt bullshot

  • Super Contributor
  • ***
  • Posts: 3033
  • Country: de
    • Mostly useless stuff, but nice to have: wunderkis.de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103442 on: September 27, 2021, 06:02:10 am »
Testing the preliminary fixed TA520 by measuring the wander of a cheap GPS module PPS output vs. the True Position GPSDO PPS output - or fine arts japanese technology vs. rock solid HPAK:

TA520 and 53131A - the perfect team for timenuttery

Just a FYI based on my experiences with the 53132A so far. If the 53131A with the HS oven option behaves the same as the 53132A with the US option oven it needs several days of standby/power on to reach ultimate stability. The OCXOs are the same design, just different grades with the US being picked out and given the appropriate part number, so I expect they do. Worth noting if you're really going to get into it, not worth noting if something of the close order of 1 ppb/day drift isn't going to bother you because you're just doing relatively short term comparative measurements.

Thanks. This matches my experience with the OCXOs of the homebrew GPSDO and the True Position one. While I did these stability measurements on them, the first days were slightly worse than after a few days continuously running them. So there will be some side usage on the 53131A - watching the stability of its oscillator.
Safety devices hinder evolution
 

Offline Robert763

  • Super Contributor
  • ***
  • Posts: 2779
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103443 on: September 27, 2021, 08:56:46 am »
Testing the preliminary fixed TA520 by measuring the wander of a cheap GPS module PPS output vs. the True Position GPSDO PPS output - or fine arts japanese technology vs. rock solid HPAK:

TA520 and 53131A - the perfect team for timenuttery

Just a FYI based on my experiences with the 53132A so far. If the 53131A with the HS oven option behaves the same as the 53132A with the US option oven it needs several days of standby/power on to reach ultimate stability. The OCXOs are the same design, just different grades with the US being picked out and given the appropriate part number, so I expect they do. Worth noting if you're really going to get into it, not worth noting if something of the close order of 1 ppb/day drift isn't going to bother you because you're just doing relatively short term comparative measurements.

Thanks. This matches my experience with the OCXOs of the homebrew GPSDO and the True Position one. While I did these stability measurements on them, the first days were slightly worse than after a few days continuously running them. So there will be some side usage on the 53131A - watching the stability of its oscillator.

Which True Position unit do you have, the LMU300?

I have the GPSDO from one of these
www.ebay.co.uk/itm/163610445099
Waiting in thg to do line. The seller was kind enough to pull just the GPSDO board and interconnect leads from the unit for me. The postae for the whole thing would have been excessive.
For those in the USA they are a bargain.
 

Offline capt bullshot

  • Super Contributor
  • ***
  • Posts: 3033
  • Country: de
    • Mostly useless stuff, but nice to have: wunderkis.de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103444 on: September 27, 2021, 09:07:09 am »

Which True Position unit do you have, the LMU300?


It's one of these, forum member RoadRunner built and sold them some time ago:
https://www.circuitvalley.com/2018/07/gpsdo-10mhz-standard-reference-clock-distribution-trueposition-gps-tcxo-ocxo.html
Safety devices hinder evolution
 

Online Vince

  • Super Contributor
  • ***
  • Posts: 4168
  • Country: fr
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103445 on: September 27, 2021, 10:32:31 am »

For something that is actually interesting, a RM564
Is this something reasonable for someone (me) who has not worked on one of these before?
I like the idea that it is rack mountable...  might be worth a low-ball offer.
Biggest problem is that it is far away, closer to where the dwagon lives used to live.



Here !  I was in your position 4 years ago when I embarked into the restoration of my first tube anything, a Tek 317 scope.

Here is my take on it.

1) Don't know about the Canadian market, but here a rack mount Tek scope of any model and vintage is very rare. So if really you want a rack mount Tek scope, the obvious is to get it before someone else does, especially since the price is fair as it is. If you get to start work on it in a year or two only, and have by some miracle found another rack-mount scope that you like better, you can always sell the firsts one if you want to, but more likely you will keep it as a part mule to help you fix the "new" one. Being able to to quickly swap tubes is priceless. Saves you from buying new tubes you might not even need, and waste time waiting for them being delivered.

2) As was said, if really you feel overwhelmed by that (apparent only) complexity of a Tek tube scope, yeah why not get some simpler piece of tube equipment. 

3) 564 is all tubes no trannies, well according to Tekwiki at least. 564B is 100% PCB and transistors, well  I mean the chassis itself only. The plug-ins of course are whatever you decide to use, so will probably be tube based.

4) Look at pics of the 564 on Tekwiki : once you remove the plugins, the circuitry of the main frame is readily accessible on both side, just pop the top and bottom covers and your right there probing around.

5) Cats and humans : doesn't your lab have a door that can close ?!  If you are in the lab, well of course you are there to tell people to be careful, but I guess by now they must already know they should not approach or touch stuff plugged in on the bench anyway ?!
Then when you are NOT in the lab hence can't see what others are doing... well I will state the obvious and say that you should not leave an old tube scope unattended for too long... just in case !  :-DD   If you need/want to anyway, well just close the door. IF it does not have a key... put a huge red sign on the door to INSTRUCT people not to enter because of dangerous high-voltages on the bench.

6) Learning tubes. I don't know how little you know. You probably know more than I did. I am not that old so never learned anything about tubes at school. Didn't even know they existed. So to me they couldn't possibly be more mysterious... I had no idea what principles governed their operation, had n idea what all the pins did, had n idea what all the weird looking symbols meant on the schematics. It was black magic to me, pure and simple. Alien.

So I too was scared and reluctant at first, fearing for my safety and feeling I would be too incompetent to fix it.  But you know what ? It's all BS ! As Mansaxel said, tubes are very simple ! Of course you can come across the odd one with a weird failure mode... but you get to know the various failure modes, just like any device, no big deal. Plus in practice most of them aren't defective.. they are just "tired", low gain, that's all.
It's not like solid-state was any better ! They too can have their weird failure modes too ! An intermittent bond inside an IC package isn't exactly the most obvious and  fun thing to debug for a new comer I would think !
Plus, you don't even need to be an expert in all faluure modes (certainly I am NOT !  :-DD ) to be able to tell if a tube is bad !
In practice what you do is work on a particular section of the circuit, say stage 3 of the vertical amplifier or whatever... you see the signal coming in is good, coming out isn't good any more, so you know something is going on there. Can be either the tube or the discrete components around it. So you just check supply voltages, then look for visual clues of a damaged discrete component, then measure them quickly with your DMM.. if all is well then just swap the tube as see if that fixes it ! Job done. Next.

The good thing with old Tube Tek scopes is they all have a very comprehensive service manual. Block diagram, and a lengthy description of how each and every section of the scope works. The on the schematics, you have test points showing DC voltages as well as waveform.

So you just go through that calmly, methodically... and you will fix that scope I am sure ! Plus of course, you are not alone ! You can post on here, and of course subscribe to the "Tekscope" mailing list, where all the tube Tek grey beards/experts reside ! They have alwyas been very friendly and helpful to me !  :-+

To make sense of the schematics : it's easy, no really ! Just consider the tube as FET transistor...3 pins. The "grid" is like the gate, "anode" is like the drain, and the "source" is like the cathode. That's all. You give the anode some juice, 200 or 300 or 500 volts, apply some voltage at the grid and you will get more or less current flowing between the anode and cathode. That's it basically !  Don't care about all the other pins  ! You have two pins for the filament/heater... all you need to know is that it's powered on all the time and is required for the tube to work.  It's merely an accessory. You need it, you know it's there, but it's not required to understand/read the schematics. So much so that as you will see, the filaments are not even represented in the schematics ! You only see them appearing once, all grouped together, in the power supply schematic.. of course, because you need to power these filaments. But in all other schematics, every time you se a tube symbol, you will NOT see the filament. It's just not required to the understanding of the circuit.
What you might see in schematics is EXTRA pins here and there.... A "Triode" as its name suggests, as only 3 active pins : the 3 pins analogous of the FET transistor discussed above. It's the bare minimum you need for the thing to work. but you can also have a "Pentode" tube.. again as the name suggests, it has 5 pins not 3. However, these two extra pins... you don't even need to care about 99,999999% of the time. The designers had to care... but for repair purpose, just ignore them plain and simple. Usually tehy are just tied to fixed potential via a high impedance resistor divider, and often times, these extra pins are simply tied directly to one of the other power supplies, or to the cathode....  really you can just ignore them. Just look at the grid/anode/cathode, that's, the "transistor".. it's all that you need to understand how things work.  Sometimes, one of these two extra pins will NOT even be accessible ! It will already have been, internally, connected to the cathode or whatever.

Once you have all that in mind... you can read the schematic easily. Every time you see a tube you just see a FET transistor, and then suddenly it all seems simple and clear as water !  :D  .... and you will realize that all the common transistor circuits you learned at school, astable/multivibrator, flip-flop, amplifiers, voltage regulators etc... were not transistors inventions... they were already all designed and working with tubes, and only adapted later to make use of trannies.. just adapted, not invented, not new stuff... there is no black magic at all in tube circuits !


So... I say, grab this rack mount scope while you can because god knows how long it might be before you can find another one especially at a fair price like this.  Then you have all the time in the world to see how you want to proceed about it...
Pop the covers, see for yourself how it's put together. Read the manual, identify where each section is.. familiarize yourself with the scope...
If you still don't feel like going straight at it, yeah as was suggested, why not grab whatever cheap piece of junk TE that's got tubes in it but is simpler in design, less tubes.. and get some hand-on experience on it.. then start probing around your Tek scope progressively, a step at a time !

Have fun, I sure do !!!   :D

« Last Edit: September 27, 2021, 10:39:35 am by Vince »
 
The following users thanked this post: mnementh, capt bullshot, cyclin_al

Offline mansaxel

  • Super Contributor
  • ***
  • Posts: 3554
  • Country: se
  • SA0XLR
    • My very static home page
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103446 on: September 27, 2021, 10:34:24 am »
Aw, fuck. I'd been ogling a 410b for a couple weeks. I have one already, but this one came with not one but two probe-> N coax connector adapters, which always are AWOL on these.



It went from ~$60 to $170 in like 30 sec. Outta my league.

Offline Specmaster

  • Super Contributor
  • ***
  • Posts: 14483
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103447 on: September 27, 2021, 10:50:16 am »

For something that is actually interesting, a RM564
https://www.kijiji.ca/v-general-electronics/markham-york-region/tektronix-rm564-vacuum-tube-type-oscilloscope-and-2-extra-module/1585100005
Is this something reasonable for someone (me) who has not worked on one of these before?
I like the idea that it is rack mountable...  might be worth a low-ball offer.
Biggest problem is that it is far away, closer to where the dwagon lives used to live.


Well, how familiar are you with working with vacuum tube circuits? Not sure if the RM564 has a vacuum tube PSU or sand state. Could be either depending upon what year it was made. The plug-in's are definitely a hybrid design of hollow state and sand state. They can be difficult if not near impossible to service without a plug-in extender (I have one). Although with the rack mount you might have better access than the bench version. Don't know for sure since I have no rack mount 560 series. And of course the high voltages associated with tube circuits.

Thanks Mike,

The one point that you make that is the big one is vacuum tube circuits.  In all honesty, I am not familiar with working with these.  I know taking on this scope would involve me taking a step up.  Is it reasonable to step up to tubes at the same time as stepping up to a scope like this?

Something like this would be a "reach project"; more of a long-term goal to dream about.
There are a few steps along the way.
First, I need to create a proper lab space suitable for high voltage.  That needs some house renovation to be finished.
There are other people and furry family members about, so need a lab space that is controlled off-limits.
What all the means, is that I am looking at a number of progressions to get there, and it is going to take some time.
I do not expect to jump in and start on it right away.  Even when I do start on it, I do not expect to finish it up quickly.

I am open to suggestions like do a project with scope xyz first to build up skills, or do project xxx with vacuum tubes first.
I also have to decide for myself whether to get this scope now and have to store it while renovation is done, or whether I should hold off until I am ready and see what opportunities are available at that time.
When I first saw the model number, I had to do a double take, RM564 was also the fleet designation of a London Transport Routemaster bus before they were withdrawn from service.
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Offline Robert763

  • Super Contributor
  • ***
  • Posts: 2779
  • Country: gb
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103448 on: September 27, 2021, 10:55:30 am »

Which True Position unit do you have, the LMU300?


It's one of these, forum member RoadRunner built and sold them some time ago:
https://www.circuitvalley.com/2018/07/gpsdo-10mhz-standard-reference-clock-distribution-trueposition-gps-tcxo-ocxo.html
Nice design. Seems to use an earlier version of the GPSDO board from the same LMU300 Telco box that mine came from.
« Last Edit: September 27, 2021, 10:58:28 am by Robert763 »
 

Offline Neper

  • Frequent Contributor
  • **
  • Posts: 543
  • Country: de
Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #103449 on: September 27, 2021, 10:59:01 am »
5) Cats and humans : doesn't your lab have a door that can close ?! 

Cats and closed doors? I guess I'm stating the obvious by supposing you've never had a cat. So, insert your anti-cat rant here:


« Last Edit: September 27, 2021, 11:22:54 am by Neper »
If I knew everything I'd be starving because no-one could afford me.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf