Date   

Re: Large number of people unsubscribing to YAHOO TekScopes

 

Dennis

You might also want to change the colored logo photo of the inside of a scope to a Text-based image "Moved to Tekscopes@groups.io"


Re: Another miserable tantalum!

Shailendra Krishan
 

Hi Ernesto,

I stand corrected. How can you forget the dynamic timer....having worked on data processing machines of that bygone era. I have followed a very similar path as you, but I jumped from 447 to IBM 1401, IBM 1620, and then onwards to IBM 360 and its successors right up to the water cooled mainframes.

My current oscilloscope, a Tektronix 465b is one of the many which my employer disposed off when they were no longer needed. I have fixed many a problems on it using information gained through TekScopes forum.

Sorry if my ramblings wasted some time of yours and other members.

Shailendra


Re: Question re: capacitor in Tek 181

Harvey White
 

Might have been a timing capacitor they had a lot of, hence the very precise value.

Me, I'd give it about 100 volts headroom.  Then again, I tend to overdesign stuff.

Harvey

On 5/2/2020 9:08 PM, Brenda via groups.io wrote:
Sorry that I am late to this thread, I had a really busy day!

I don't know, I think some of the folks on here are right, that it may have just been an overstock and they decided to use this value. But either way, 6.25uf is a very odd value as capacitors back in the day were not that precise. But since I do not have a printed manual (I prefer printed manuals over pdf's), and I am sure that Brad is right, I am just wondering if a 450V capacitor is overkill, maybe a 50V or 250V 10uf would be more sensible. Or maybe I should use the 450V and have that nice big headroom.

Brenda



Re: Tek 7000 series extenders ?

 

I think it is a typo instead of "EDAC". Just google "345-076-520-201"

Ernesto


Re: Question re: capacitor in Tek 181

Brenda
 

Sorry that I am late to this thread, I had a really busy day!

I don't know, I think some of the folks on here are right, that it may have just been an overstock and they decided to use this value. But either way, 6.25uf is a very odd value as capacitors back in the day were not that precise. But since I do not have a printed manual (I prefer printed manuals over pdf's), and I am sure that Brad is right, I am just wondering if a 450V capacitor is overkill, maybe a 50V or 250V 10uf would be more sensible. Or maybe I should use the 450V and have that nice big headroom.

Brenda


Re: Tek 7000 series extenders ?

Dave Daniel
 

What is “EORG”?

On May 2, 2020, at 20:10, Ernesto <ebordon@...> wrote:

The female connector used in the 7000 mainframes seems to be equivalent to:
EORG 345-076-520-201

Ernesto



Re: Lots more goodies added to Stuff Season, CRTs, Tek, HP, Fluke., Xantrex..

Dave Daniel
 

Thanks, Walter.

Somebody needs to buy the Tektronix 7934. Those are pretty rare and $375 is a good price (at least IMHO).

DaveD

On May 2, 2020, at 19:43, walter shawlee <@walter2> wrote:

Since we can't have our giant stuff day party here, thanks to the evil covid-19, we have moved it on line, and
I am adding new goodies daily. Everybody gets some free stuff with anything they order,
and there are some very nice items to be found. and yes, we take requests if you need something you don't see there!
find it all here:
https://www.sphere.bc.ca/test/stuffday.html

anybody can play!
there are over 100 CRTs after the equipment and parts listings, all going cheap. also, I am tryign to find an hp 85046A s-parameter test set to go with my 8753A VNA, happy to buy or trade. I have a lot of related hp goodies to swap, 8503A, 35677B, 8501A, 8750A, so let me know if you can help.

also a nice 7934 Tek scope system available, and notice the FREE TM500 plug in offer. I also have a big box of Tek CRT sockets/cables if anybody can use them. hard item to find when you want it...
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
https://www.sphere.bc.ca/test/index.html



Re: Tek 7000 series extenders ?

 

The female connector used in the 7000 mainframes seems to be equivalent to:
EORG 345-076-520-201

Ernesto


Re: Question re: capacitor in Tek 181

 

Hi Brad,

A while ago I received a private message from Dan G. to make me aware that the can of C401 is floating at a negative supply.

I appreciate very much his use of the private message to avoid embarrassing me here for having overseen this important detail, even when at my age I have lost all shame, ha ha.

I had assumed, without certainty, that C401 is the same part as C430 and C431 just mounted on an insulating sleeve. But there are no drawings in the maintenance manual, and I could be wrong.
I was always the project designer engineer, and someone else did the product engineering. There was always collaboration, but different perspectives.
This is why I can easily be wrong in my opinions here.

Ernesto


Re: 2440 cal errors

dabono@...
 

Does anybody know around which serial # the 2440 switched from using a backup battery to using NVRAM? I'm looking at purchasing one on eBay that has an FPP diagnostic error - serial #B013530 (I think).

Thanks!
David Bono


Re: 496 looses the magic smoke

Greg
 

"Now U301 is listed on the schematic as a "safety part" . Following back from the parts the manufacturer of this little assembly is still in business and you can actually order the part against the original manufacturers part number ( at almost $50 a bit steep for a resistor and cap IMO"
I found that part in the schematic for the main power supply but couldn't find it in parts. Is there a special page for safety parts? Is U301 considered an electronic part or mechanical one? I might want to replace mine. Thanks for that story! Greg


Lots more goodies added to Stuff Season, CRTs, Tek, HP, Fluke., Xantrex..

 

Since we can't have our giant stuff day party here, thanks to the evil covid-19, we have moved it on line, and
I am adding new goodies daily. Everybody gets some free stuff with anything they order,
and there are some very nice items to be found. and yes, we take requests if you need something you don't see there!
find it all here:
https://www.sphere.bc.ca/test/stuffday.html

anybody can play!
there are over 100 CRTs after the equipment and parts listings, all going cheap. also, I am tryign to find an hp 85046A s-parameter test set to go with my 8753A VNA, happy to buy or trade. I have a lot of related hp goodies to swap, 8503A, 35677B, 8501A, 8750A, so let me know if you can help.

also a nice 7934 Tek scope system available, and notice the FREE TM500 plug in offer. I also have a big box of Tek CRT sockets/cables if anybody can use them. hard item to find when you want it...
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
https://www.sphere.bc.ca/test/index.html


Re: Question re: capacitor in Tek 181

Brad Thompson
 

Ernesto wrote on 5/2/2020 3:35 PM:

Hi Brad,

Another question is why C401, which has identical description as C430 and C431, (2x20uF, 450V, -10%, +50%), has a different part number.
Hello, Ernesto--

C401A and C401B are listed as 2X20 uF, p/n 290-036.
C430 is listed as (2X20 uF), p/n 290-037
C431A and C431B are listed as 2x 20 uF, p/n 290-037

In the schematic, C430 appears as a single 40 uF capacitor-- it's connected in parallel with C431A 20 uF.
Showing C430 as C430A and C430B (20 uF each) connected in parallel would clarify matters.

As for C401 and C431 having two different part numbers, perhaps C431 gets prepped with an insulating
cover (since its can floats at -150 volts with respect to the chassis) and hence deserves its own part number?

Maybe the Tek engineer was also a unique artist, like Leonardo Da Vinci, and wanted other engineers to stand in admiration in front of his designs asking themselves questions, like the public standing in front of the Mona Lisa ask themselves "why is she smiling?".
From an engineering viewpoint, The "Mona Lisa" could have been painted on a smaller canvas for
more efficient use of materials.<g> (Ear protection in place to muffle outraged howls emanating
from artaficionados).

My personal take on this is that if we wonder why some piece of equipment seems over designed or under designed, or over specified or under specified, we should not assume that there was some esoteric reason in the superior mind of the designer, but take it as some mundane oversight. And we are free to follow that detail or not. (stated by a former designer).
Or as someone suggested, perhaps there were leftover 6.25 uF caps in stock. Never underestimate
a buyer or purchasing agent's appetite  for shortcuts.

I served as components engineer for a small (soon to be even smaller) company. One of the purchasers
called me into his office and explained that a crystal manufacturer had mislabeled a batch of 14.7xx MHz crystals as
17.4xx MHz crystals and could we accept the lot as-is and just make a note in the schematic?

I pointed out that the already beleaguered (*) field service engineers were struggling with a
severe case of board float, and the only way that those crystals could be acceptable would
be if the manufacturer took back the lot and applied shrink-wrap sleeves marked with the
correct frequency on each crystal.

The buyer didn't want to "bother" the manufacturer-- after all, only 100 parts were involved and
couldn't I be a little more flexible?

No, I couldn't and the whole g----ed lot is hereby rejected.

73--

Brad   AA1IP

Beleaguered (n):  a 16 by 16-inch, six-layer boards with approximately 120 ECO cuts and wires.


Re: Which type of transistor is SG503 Q190 151-0614-00?

boid_twitty
 

Maybe check the emitter resistors. Any variation in current through
these will give a difference in vbe between 'disassociated' emitters
that don't have the same emitter current.

The one conducting more will also have a larger internal ballast resistor
drop than intended.

RL


Re: Tek 7000 series extenders ?

WastelandTek
 

good to know, thank you for clarifying that


Re: Tek 5440

WastelandTek
 

can confirm, the slower plugins are good in the faster frames

I too am a big fan of the non storage 5400 scopes


Re: Tek 5440

Harvey White
 

Thanks.  What I was remembering is that there's a different keying from the 5400 frame to the 5000 frame.  Didn't know that some were transplantable.  I'll have to get my 5000 and 5400 frames up and running.

Harvey

On 5/2/2020 5:33 PM, Szabolcs Szigeti wrote:
Hi,

5000 plugins do fit and work in the 5400. But not the other way around. Of
course the bandwidth is limited by the plugin and no readout.
I have some 5000 series plugin such as the 5a14 or the 5ct1, that I use in
my 5440 scope, which I love btw.

Szabolcs


Harvey White <madyn@...> ezt írta (időpont: 2020. máj. 2., Szo
0:03):

From what I understand, the 5000 series is good to 1 or 2 Mhz, the 5400
series is good to 60. However, the 5400 series plugins do not fit into
the 5000 series frames, nor do the 5000 series fit in the 5400 frames.

Harvey


On 5/1/2020 5:05 PM, Jim Ford wrote:
Also, Ron, you will want to know that the 5400 series can use plug-ins
up to 60 MHz bandwidth, but if you use the 5A1*, 5A2*, and/or 5B1*
plug-ins, the BW will be limited to 1-2 MHz. That may be a good thing
for audio work. What plug-ins do you have? I have a 5103N/D10
(equivalent to the later 5110N) with two 5A15N and one 5B10N. I love
the big, bright screen, and the low BW is perfect for audio.

Definitely bookmark http://www.w140.com/tekwiki/ if you haven't
already, for all things Tektronix. Good luck with your rack-mount
conversion!

Best,
Jim Ford
Laguna Hills, California
USA

------ Original Message ------
From: "Tim Phillips" <timexucl@...>
To: TekScopes@groups.io
Sent: 5/1/2020 12:30:02 AM
Subject: Re: [TekScopes] Tek 5440

from Tim P (UK)
I've converted a few 5111s the other way (rak to bench) . The two halves
come apart reasonably easily - two low-profile bolts just by the top
plugin
guides and two long-headed hex bolts at the rear. You may need a
flexible
nut-driver to get to these. Then disconnect all the ribbon connectors,
noting where they all go - a mistake re-installing the 10-way connector
between the LVPS and the HV board will set all your efforts at naught.
(Don't ask !!) Don't forget the twin wire from LVPS to HV board for the
CRT. Also, with the 5440 there is a delay line which I think needs
re-routing and / or disconnecting. Not sure whether it needs unsoldering
(very thin wires) or can be moved by moving the vertical amp board.
You will also need different covers, and different spacers although
you may
be able to fab something. If you have a manual, it shows how the two
variants fit mechanically.
Bon Chance !!
Tim


On Fri, 1 May 2020 at 06:05, Ron Smith via groups.io <mercedesmann=
yahoo.com@groups.io> wrote:

I bought a Tektronix 5440 on ebay recently b/c I like the big
screen and I
am using it it for some audio work. I was wondering if anyone has ever
converted this upright model to a rack-mount configuration. It
looks like
the modules are fairly similar to the rack-mount version. If the wire
connectors are long enough I think that is the way it will set up
better on
my bench. I bought the upright model because it was in very good
shape and
it was a good price, but now that I look at the way my bench is
evolving it
looks like that might be better for my set up. Just wondering if
anyone has
the 411 on that.






Re: Which type of transistor is SG503 Q190 151-0614-00?

Ed Breya
 

OK, you made me look. I downloaded the SG503 manual, and in the schematics I don't see any problem with Q190 - it's just a dual-emitter RF power transistor.. You should be able to replace it with a similar one, or one where the emitters are tied internally.

I vaguely recall seeing these kinds in old Motorola catalogs. The purpose may have been to reduce the C-E capacitance, or more likely to help get better DC thermal balance and uniformity in the rather large emitter area, by splitting it in two and allowing separate degeneration resistors. More improved later device processes may have provided better current density uniformity, making split emitters unnecessary.

I also vaguely recall seeing RF power transistor designs where there were a whole bunch of emitters, each with a small built-in degeneration resistor, and all of them tied together and then out to a single terminal. This detail is not shown in the symbol, which is typically just a single transistor, but it was available in the olden days, when the makers bragged about their processes and showed the die layouts and design concepts. It may be that even modern ones are made nearly the same way, with multiple emitters inside, or other techniques to get uniform current density, but you'd never know it from the symbol.

BTW when I said earlier that Darlingtons are never used as RF amps, I was referring to the typical discrete Darlington power transistors of the day, which were for very high gain, low frequency use in regulators and drivers and such. Of course the Darlington structure may appear in lots of integrated circuit sections, from opamps to coil drivers to RF amps and so forth. The common MMIC three-terminal RF amps use it too, along with some internal resistors, to form a self-biased shunt-feedback amplifier, when hooked up to a few external parts. I would not call it a Darlington transistor though - it would not function like one. You could put one on a curve tracer and see the difference, or simply think about the internal circuit.

So anyway, your Q190 is just a dual-emitter part, for whatever reason. I wouldn't worry about it too much, unless some day it needs replacement.

Ed


Re: Tek 5440

Szabolcs Szigeti
 

Hi,

5000 plugins do fit and work in the 5400. But not the other way around. Of
course the bandwidth is limited by the plugin and no readout.
I have some 5000 series plugin such as the 5a14 or the 5ct1, that I use in
my 5440 scope, which I love btw.

Szabolcs


Harvey White <madyn@...> ezt írta (időpont: 2020. máj. 2., Szo
0:03):

From what I understand, the 5000 series is good to 1 or 2 Mhz, the 5400
series is good to 60. However, the 5400 series plugins do not fit into
the 5000 series frames, nor do the 5000 series fit in the 5400 frames.

Harvey


On 5/1/2020 5:05 PM, Jim Ford wrote:
Also, Ron, you will want to know that the 5400 series can use plug-ins
up to 60 MHz bandwidth, but if you use the 5A1*, 5A2*, and/or 5B1*
plug-ins, the BW will be limited to 1-2 MHz. That may be a good thing
for audio work. What plug-ins do you have? I have a 5103N/D10
(equivalent to the later 5110N) with two 5A15N and one 5B10N. I love
the big, bright screen, and the low BW is perfect for audio.

Definitely bookmark http://www.w140.com/tekwiki/ if you haven't
already, for all things Tektronix. Good luck with your rack-mount
conversion!

Best,
Jim Ford
Laguna Hills, California
USA

------ Original Message ------
From: "Tim Phillips" <timexucl@...>
To: TekScopes@groups.io
Sent: 5/1/2020 12:30:02 AM
Subject: Re: [TekScopes] Tek 5440

from Tim P (UK)
I've converted a few 5111s the other way (rak to bench) . The two halves
come apart reasonably easily - two low-profile bolts just by the top
plugin
guides and two long-headed hex bolts at the rear. You may need a
flexible
nut-driver to get to these. Then disconnect all the ribbon connectors,
noting where they all go - a mistake re-installing the 10-way connector
between the LVPS and the HV board will set all your efforts at naught.
(Don't ask !!) Don't forget the twin wire from LVPS to HV board for the
CRT. Also, with the 5440 there is a delay line which I think needs
re-routing and / or disconnecting. Not sure whether it needs unsoldering
(very thin wires) or can be moved by moving the vertical amp board.
You will also need different covers, and different spacers although
you may
be able to fab something. If you have a manual, it shows how the two
variants fit mechanically.
Bon Chance !!
Tim


On Fri, 1 May 2020 at 06:05, Ron Smith via groups.io <mercedesmann=
yahoo.com@groups.io> wrote:

I bought a Tektronix 5440 on ebay recently b/c I like the big
screen and I
am using it it for some audio work. I was wondering if anyone has ever
converted this upright model to a rack-mount configuration. It
looks like
the modules are fairly similar to the rack-mount version. If the wire
connectors are long enough I think that is the way it will set up
better on
my bench. I bought the upright model because it was in very good
shape and
it was a good price, but now that I look at the way my bench is
evolving it
looks like that might be better for my set up. Just wondering if
anyone has
the 411 on that.









Re: Which type of transistor is SG503 Q190 151-0614-00?

Albert Otten
 

Hi Ernesto,

In my 7A13 the usual problem with the relays is of more concern to me. But I'll have a look at C518.
BTW I might also have used a 7A13 in a dual input differential way to compare say E1 and E2 but then I would have to hold 2 probe tips in place. That's somewhat more risky.

Albert

On Sat, May 2, 2020 at 10:27 PM, Ernesto wrote:


Hi Albert,

You gave me a good example of the use of a 7A13 differential comparator.
I put away my 7A13 after it was disabled by the blowout of C518, a tantalum
cap on the +15V.

You may want to replace this capacitor too, for a continuing happy use of this
plugin.

Ernesto