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Date
Re: Tek 577 sells for $256 on eBay

 

My main interest in a curve tracer would be for tube testing/matching. A
few months back, I believe there was discussion of a home-grown 576 fixture
for that. For now, one of my upcoming projects is to build my own tube
testing rig. For example, I'd wire up a single socket to some voltage and
amperage gauges and power the rig with an external DC supply across a
mixture of plate voltage and cathode resistance ranges. But that's a a lot
of work for each tube. I've seen a few hacks that convert old oscilloscopes
into curve tracers but haven't really studied any of them.

On Mon, May 14, 2018 at 2:43 PM, Kevin Oconnor <kjo@...> wrote:

Just chiming in...
I would agree with Chuck on this. Some other factors...
A 576 is way more complex inside with all the display lighting and control.
If something fails, you have a lot more work to do. I just sold a 576 for
$750 and I think, for a fully working unit, it was a buyer bargain. The
owner just wanted it gone....

I use a 577 for just about anything discrete. I have a dozen fixtures. (No
IC testing though as mine has the 177 fixture) . Both are versatile, and
you can build fixtures to do things Tek didn't anticipate or support. I'm
working on a fixture to test Nuvistors.. A work in progress though.

One caution (among many) If you get one and then go looking for fixtures,
be ware that many of the Tek plug-in fixtures have reached EOL. The covers
are screwed into bosses in the base boxes. Both the threaded bosses and the
covers themselves are now failing. As the plastics aged they became brittle
and the stresses have fractured the bosses and the covers now pull away
from the base. I have seen top covers laced with hairline cracks causing
the top to break up like a jig-saw puzzle. So take a good look at what you
are buying.

kjo

David Berlind wrote:
. . .
I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not
sure if that power-up trace indicates an issue (not having had or operated
a curve tracer, I don't know what the power-up trace should look like).
Following-on to conversations in this forum about the the 576, I've been
keeping my eyes out for a 576. Is there a significant difference between
the two?
Re: 7M11 copy (Soviet Ya4S-102) delay line performance

 

On Mon, May 14, 2018 at 10:10 am, tmillermdems wrote:
Tell us about the mod to the CSA803A delay line. What did you do to add the
third SMA connector to the delay lines. Is that just the internal end of the
line?
My CSA803A has become a 'frankenscope' inspired by Hakan's similar effort, so I can't claim any originality. I bought a scrap 11802 and used the acquisition module from it, which includes the delay lines, swapping the boards from my CSA803A which had slightly newer software on them. The 11802 has connections internally for the trigger outputs from the delay line, but the CSA803A doesn't. I decided to bring them out to the front panel so they could be connected with flying leads to the front panel trigger input. Those are the extra SMA sockets you can see below the delay line inputs and outputs. The splitter at the input of each delay line has an SMA socket on it for the trigger output. Originally these went to SMA-Peltola cables, but I replaced them with short (5 or 10cm, I can't remember) semirigid pigtails to bring them out to the front panel. It's a bit fiddly to get the position of the SMA sockets right because there's not much room to work in amongst all the plumbing!

The whole setup is very practical. I don't miss the 'power only' slots on the original CSA803A. I'm not likely to do any optical measurements any time soon (though I do have an optical receiver module that came with my mainframe) and I don't have a trigger countdown head either.

Chris
Re: 7T11 sampling timebase - how does it behave?

 

I'd say the 36-40 pSec tr displayed result is in the right ballpark. If the tr of the pulse and the the sampler are both 25 pSec, then the net would be about 35. If they are both 30 pSec, then it would net about 42.

Ed
Re: Tek 577 sells for $256 on eBay

 

Just chiming in...
I would agree with Chuck on this. Some other factors...
A 576 is way more complex inside with all the display lighting and control.
If something fails, you have a lot more work to do. I just sold a 576 for $750 and I think, for a fully working unit, it was a buyer bargain. The owner just wanted it gone....

I use a 577 for just about anything discrete. I have a dozen fixtures. (No IC testing though as mine has the 177 fixture) . Both are versatile, and you can build fixtures to do things Tek didn't anticipate or support. I'm working on a fixture to test Nuvistors.. A work in progress though.

One caution (among many) If you get one and then go looking for fixtures, be ware that many of the Tek plug-in fixtures have reached EOL. The covers are screwed into bosses in the base boxes. Both the threaded bosses and the covers themselves are now failing. As the plastics aged they became brittle and the stresses have fractured the bosses and the covers now pull away from the base. I have seen top covers laced with hairline cracks causing the top to break up like a jig-saw puzzle. So take a good look at what you are buying.

kjo

David Berlind wrote:
. . .
I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not sure if that power-up trace indicates an issue (not having had or operated a curve tracer, I don't know what the power-up trace should look like). Following-on to conversations in this forum about the the 576, I've been keeping my eyes out for a 576. Is there a significant difference between the two?
Re: 7T11 sampling timebase - how does it behave?

 

Hi Dennis,
I took a few photographs with current equipment and my previous measurements were largely confirmed. Please refer to the added photographs in the album. Their names indicate what's shown, as opposed to the older photographs which only carry their image number.
I apologise for the disappointing quality of the "rush job".
I used two 'scopes and two S-52's:
- A 7854 with 7T11A, 7S11/S-52 and 7S11/S-4
- A 7904 with 7S12, S-52 and S-6, terminated

You seem to have 30pSec risetime and I would like to know how you do that since the S4 has a 25pS rise time. That would
mean you were using a 13pS pulse.
I'd say slightly more: 36 to almost 40 ps, ignoring the influence of overshoot. The sampling outfits are separate. I've never attempted to adjust the time bases and adjusted the horizontal sensitivity of the mainframes using a Calibration Fixture (067-0587-01), calibrated against a second unit so I'm tempted to trust the measurements. ISTR that Tek specified minimum ("at least") specs for the samplers and pulse generators. I also STR that it was not easy to measure the performance of these heads at the time (state of the art technology) so specs may have been very conservative. You're definitely far more knowledgeable on this than I.

The 2nd photo must have been on a 7854 since the time jitter at 20ps is almost 0ps.
Surprise! I used the High Resolution setting of the 7S12 in the 7603. I repeated it today in the 7904. Please refer to today's picture.

You didn't say what your signal source was in any of these photos. Was it the S-52: If so how did you get it to trigger.
I was aware that the 2nd pulse was taller and I tried to trigger on it but I could only trigger on both simultaneously which
made for a very confusing waveform and a lot of knob twiddling to no avail.
I used two different S-52's, please refer to the new photographs. In the 7T11A setup, I used internal triggering. Only with the trigger amp. on X1 I was able to filter out the one waveform, strangely enough. I remember the same thing from my previous experiments.

Please let me know if you can't derive a setting from the new images in the album.

Raymond
Re: PG502 Failure points?

 

On Mon, 14 May 2018 06:11:27 -0700, you wrote:

I have acquired a TM506 with 7 plug ins PG506,TG501,DC503A,PG502,SG503,SG504 and DM502. All the units seem to work except the PG502. Looking for some guidance as to the likely failure points of this module from the much more experienced members. The TM506 had a fan that had just exploded and was locked up. I replaced the fan and found that the PG502 was not powering on, the power light on the panel did not come on. I found that It had a blown F645 1A sub-miniature fuse on the board, I replaced that fuse and now when I plug it in and turn on the power, it blows the 7A fuse on the board of the TM506. Funny thing is that the little sub miniature that I replaced does not blow when this happens. I immediately stopped inserting the module, in fear that it might cause some other damage to the TM506. Anyone have any ideas? I do not want to keep poking around without getting some ideas from the forum. Thank You in advance!
I remember that TEK does not recommend hot insertion of modules in
equipment. Part of the problem is that if the connectors are not
aligned properly from the very start, adjacent pins can short at the
very beginning of the process, yet be correctly aligned when the
plugin is fully and properly inserted.

With no plugins, if the TM506 main fuse blows, then there's a nice
short somewhere. Obviously, if the fuse doesn't blow with no plugins,
and then blows once a plugin is inserted and power is applied, I'd be
looking at that plugin. A good set of extenders can be a very nice
addition.

As far as the PG502 is concerned, I'd check the capacitors down line
from the fuse. I'd also check the major capacitors in the PG502 just
as a matter of course, if you have an ESR checker.

Harvey
Re: 7M11 copy (Soviet Ya4S-102) delay line performance

 

Hey Chris,

Tell us about the mod to the CSA803A delay line. What did you do to add the third SMA connector to the delay lines. Is that just the internal end of the line?

Thanks,
Tom

----- Original Message -----
From: "cmjones01" <chris@...>
To: <[email protected]>
Sent: Monday, May 14, 2018 11:05 AM
Subject: [TekScopes] 7M11 copy (Soviet Ya4S-102) delay line performance


I made a bit of time today to experiment with one of the Soviet 7000-series plugin copies I got recently. It's the Ya4S-102 delay line, roughly equivalent to the Tek 7M11. Having discovered that N connectors could be persuaded to fit its SR50-262 sockets, I couldn't resist hooking it up to my TDR and seeing how it behaved. Conclusion: not too shabby, even allowing for imperfect connectors. It shows a risetime of about 125ps. I've taken photos of the test setup and results and put them on TekWiki:



I'm intended to put all my findings on TekWiki as I go through the plugins and get them working. Things are hampered a bit at the moment by a non-working timebase plugin and lack of a sampling head, but I'm persevering.

Chris
Re: 7633 readout drift

 

It's not uncommon. Sometimes you can fix it by turning the wiper back and forth a couple of times, but it can be temporary. Replacement with a quality part is the best way to go about it. In your case, I think it's desoldering that actually made it work properly. Metals expanding/contracting and slight movement during removal might've cleaned some of the dirt and oxide off the surfaces.
TM500 / 5000 Extenders - should I make more?

 

Hello Tek Heads -
I made a bunch of extenders, thank you to those that purchased through my Amazon page or through this group. I hope everyone that bought one is happy with them.
I am out of PC boards, and I'm trying to decide whether to make another batch. I sort of feel like the market for these is like 100 people and everyone that wants one (or two) has already bought them.
If you think you might want one, or if you have an opinion about the total available market for these please let me know.
I guess at the same time, if anyone that bought a set has any ideas for improvements please let me know that, too. If I do happen to make more I'll improve them if I can.
One thing I did was make the SMT parts larger (the resistors are 1206 and the diodes are SMA size, and the LEDs are T-1 through-hole parts). This is for the people that just wanted to buy a kit of parts, so you can more easily solder the parts yourself, rather than me doing it.
I was thinking about this because I had two module that I fixed this weekend. Reminded how handy these things are!
Thanks -
Dan

Here's a link showing the extenders:
Re: Tek 577 sells for $256 on eBay

 

On Mon, May 14, 2018 at 06:23 am, Chuck Harris wrote:


The 576 was based on the original 7000 series,
and the 577 was based on the modular 5000 series.
In what way would you say 576 is based on the 7000 series ?

/H?kan
Re: 7633 readout drift

 

On Sun, May 13, 2018 at 10:55 pm, lop pol wrote:




lop pol
11:07 am #147825

When powering on the scope from cold the readout is high by about half a
graticule. After 3-5 minutes of warm up the readout drifts to the center of
the top graticule. Is this normal for this to happen.

davehouse@...
5:12 pm #147842

No, it's supposed to be in the correct position as soon as the beam appears.
Does it drift with the trace, or independently?

Also, do you have a cold spray? The easiest way to find out the culprit is to
cool down individual components in the readout vertical signal path. I bet
it's a semiconductor, maybe the 155-0020.

On Sun, May 13, 2018 at 06:26 pm, Jeff Urban wrote:


On Sun, May 13, 2018 at 05:30 pm, lop pol wrote:


It drifts independent of the trace.
Does that mean with an actual waveform displayed so you can see if the
vertical and horizontal are changing ? Just a flat like won't tell you for
sure.

If they are changing look at HV regulation or overall PS regulation. If it
really is only the readout the look for supplies specific to that system.

Hope it is something like a supply voltage or something, that subsystem is
one
complex MF. If not, get ready for some fun and pack a lunch.
So far this is what I have figured out. the 5V line has an intermittent short.
I replaced it. /g/TekScopes/photo/49110/0?p=Name,,,20,1,0,0
Z axis transistor Qwhatfreakingever
/g/TekScopes/photo/49110/0?p=Name,,,20,1,0,0 was not
connected to its base.
And I'm pretty sure R2527 (thermal balance) is bad. Just touching it causes
the bottom readout to distort and jump to the middle of the screen. I swapped
the readout board just to make sure and the issue still persisted. Tomorrow I
will swap out the thermal balance resistor and go from there.
Swapping out the variable thermal resistor seemed to work. I checked the resistor after removing it. Seemed to check correctly. But when adjusting the thermal balance the readout does not freakout anymore. Maybe that resistor was failing when voltage was run through it? Is that a common way for those trimmer resistors to fail?
7M11 copy (Soviet Ya4S-102) delay line performance

 

I made a bit of time today to experiment with one of the Soviet 7000-series plugin copies I got recently. It's the Ya4S-102 delay line, roughly equivalent to the Tek 7M11. Having discovered that N connectors could be persuaded to fit its SR50-262 sockets, I couldn't resist hooking it up to my TDR and seeing how it behaved. Conclusion: not too shabby, even allowing for imperfect connectors. It shows a risetime of about 125ps. I've taken photos of the test setup and results and put them on TekWiki:



I'm intended to put all my findings on TekWiki as I go through the plugins and get them working. Things are hampered a bit at the moment by a non-working timebase plugin and lack of a sampling head, but I'm persevering.

Chris
Re: Tek 577 sells for $256 on eBay

Chuck Harris
 

The 576 was based on the original 7000 series,
and the 577 was based on the modular 5000 series.

The 576 was intended to do everything discrete
semiconductor wise.

The 577 was geared towards low current discretes,
opamps, and 3 terminal regulators.

They are complementary instruments, each covering
a different part of the V-I spectrum, but do not
fully replace each other.

-Chuck Harris

David Berlind wrote:

I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not sure if that power-up trace indicates an issue (not having had or operated a curve tracer, I don't know what the power-up trace should look like). Following-on to conversations in this forum about the the 576, I've been keeping my eyes out for a 576. Is there a significant difference between the two?
PG502 Failure points?

 
Edited

I have acquired a TM506 with 7 plug ins PG506,TG501,DC503A,PG502,SG503,SG504 and DM502. All the units seem to work except the PG502. Looking for some guidance as to the likely failure points of this module from the much more experienced members. The TM506 had a fan that had just exploded and was locked up. I replaced the fan and found that the PG502 was not powering on, the power light on the panel did not come on. I found that It had a blown F645 1A sub-miniature fuse on the board, I replaced that fuse and now when I plug it in and turn on the power, it blows the 7A fuse on the board of the TM506. Funny thing is that the little sub miniature that I replaced does not blow when this happens. I immediately stopped inserting the module, in fear that it might cause some other damage to the TM506. Anyone have any ideas? I do not want to keep poking around without getting some ideas from the forum. Also, Any good ideas for an extender to allow easier calibration and troubleshooting? I see these on E-bay and they seem very expensive for what they are. Thank You in advance!
Tek 577 sells for $256 on eBay

 
Edited

I saw this 577 Curve Tracer show up on eBay and it sold for $256. Not sure if that power-up trace indicates an issue (not having had or operated a curve tracer, I don't know what the power-up trace should look like). Following-on to conversations in this forum about the the 576, I've been keeping my eyes out for a 576. Is there a significant difference between the two?

Re: Automatic Brightness Control : was it ever implemented ??

 

Auto intensity on the 2215 is based on gate dutycycle, R/C averaged.
It's helpful.
Ed, k1ggi

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Chuck
Harris
Sent: Monday, May 14, 2018 7:52 AM
To: [email protected]
Subject: Re: [TekScopes] Automatic Brightness Control : was it ever
implemented ??

Seems to me, that all you would need to know
is beam velocity vs beam current.

Intensity is an integral function of beam
velocity and beam current.

So, it would take a circuit that took the vertical
deflection, horizontal deflection, and intensity
control as its inputs, calculated the absolute
velocity of the beam, integrated (differentiated?)
it in some way with the intensity control's setting,
and produced the z-axis drive.

The problem would be that you can't do the velocity
calculation, and the integration (differentiation?)
that would be necessary instantaneously, so there
would seem to be a need for more delay lines.

And, the generated z-axis control would have to
match up very closely with the beam's velocity at
any point, or you would get brightness hangover
around points where the beam speed changed quickly.

Or, you could simply digitize the fast signal, and
display it as a fixed rate raster scan, like they
do with digital scopes...

One thing: A major complaint about digital scopes
from long time analog scope users is there is no hint
of the intensity that a part of the beam would have,
leading to all sorts of tricks to make the digital
beam look more analog, with variable persistence stuff.

-Chuck Harris

Ed Breya via Groups.Io wrote:
I think that auto-brightness functions could have been implemented on
analog scopes, but only to a certain degree, and it would be quite
complicated. The operating and signal conditions can be very broad, so you
would have to take into account a lot of variables like sweep rate, signal
repetition (trigger) rate, holdoff, delayed sweep operation, whether it's in
X10 mag, the number of channels active, the chop vs alternate modes,
single-sweep mode, and so on. And that's just for the X-axis. What about the
overall deflection velocity and extent, which also depend on the arbitrary
vertical signals? You would want to know the actual peak to peak deflection,
the risetime or other frequency content information, and the position
on-screen - for every applied input signal channel, and make judgement about
which parts are to be at the "right" intensity. That's a lot of stuff to
figure out for the convenience, versus the simple way of having the user set
it for overall appearance preference for given conditions. From the advent
of the oscilloscope, all of this would have been nice to have, but is not
very practical.

In a more controlled signal and display environment, it's a bit easier.
One Tek product I know of that has some degree of auto-ness to this is the
577 curve tracer, which sort of controls intensity in proportion to the
length of the horizontal deflection. In fact, the beam can set up to blank
out entirely when the collector voltage approaches zero, so instead of a
screen-burning bright dot at the origin, it just winks out, but will come
right back as the voltage (deflection) goes back up. In this kind of
instrument, the signal frequency and deflection ranges are are quite
limited, and only so many operational modes are available, so an
auto-intensity function is more practical and effective.

Ed
Re: Automatic Brightness Control : was it ever implemented ??

Chuck Harris
 

Seems to me, that all you would need to know
is beam velocity vs beam current.

Intensity is an integral function of beam
velocity and beam current.

So, it would take a circuit that took the vertical
deflection, horizontal deflection, and intensity
control as its inputs, calculated the absolute
velocity of the beam, integrated (differentiated?)
it in some way with the intensity control's setting,
and produced the z-axis drive.

The problem would be that you can't do the velocity
calculation, and the integration (differentiation?)
that would be necessary instantaneously, so there
would seem to be a need for more delay lines.

And, the generated z-axis control would have to
match up very closely with the beam's velocity at
any point, or you would get brightness hangover
around points where the beam speed changed quickly.

Or, you could simply digitize the fast signal, and
display it as a fixed rate raster scan, like they
do with digital scopes...

One thing: A major complaint about digital scopes
from long time analog scope users is there is no hint
of the intensity that a part of the beam would have,
leading to all sorts of tricks to make the digital
beam look more analog, with variable persistence stuff.

-Chuck Harris

Ed Breya via Groups.Io wrote:

I think that auto-brightness functions could have been implemented on analog scopes, but only to a certain degree, and it would be quite complicated. The operating and signal conditions can be very broad, so you would have to take into account a lot of variables like sweep rate, signal repetition (trigger) rate, holdoff, delayed sweep operation, whether it's in X10 mag, the number of channels active, the chop vs alternate modes, single-sweep mode, and so on. And that's just for the X-axis. What about the overall deflection velocity and extent, which also depend on the arbitrary vertical signals? You would want to know the actual peak to peak deflection, the risetime or other frequency content information, and the position on-screen - for every applied input signal channel, and make judgement about which parts are to be at the "right" intensity. That's a lot of stuff to figure out for the convenience, versus the simple way of having the user set it for overall appearance preference for given conditions. From the advent of the oscilloscope, all of this would have been nice to have, but is not very practical.

In a more controlled signal and display environment, it's a bit easier. One Tek product I know of that has some degree of auto-ness to this is the 577 curve tracer, which sort of controls intensity in proportion to the length of the horizontal deflection. In fact, the beam can set up to blank out entirely when the collector voltage approaches zero, so instead of a screen-burning bright dot at the origin, it just winks out, but will come right back as the voltage (deflection) goes back up. In this kind of instrument, the signal frequency and deflection ranges are are quite limited, and only so many operational modes are available, so an auto-intensity function is more practical and effective.

Ed
Re: Upgraded, stub tuned, Tektronix SG-504 leveling head back online for a last run

 

$119.50 shipped snail mail.
Re: Help using this Group

 

I find this to be easy...
I receive each post as an individual email, not a daily digest.
I use an email client (Thunderbird or Seamonkey) that displays messages in their threads, as a tree based on their subject. Thus assuming all these messages have the same subject and each digit implies which post is a reply to which other post
1
-1.1
-1.2
--1.2.1
--1.2.2
-1.3
2
-2.1
--2.1.1
---2.1.1.1
3

I also delete most emails, keeping only those that are likely to remain particularly interesting.
I only use the web interface for searching.

On 14/05/18 02:36, tinkera123 wrote:
Hi all,

1. There are several Topics on this Site that I wish to follow closely. Is there a way for me to identify these Topics so that I don't miss any posts, even when I go away for a few weeks?? I know that I could write down the Topic name and do a Search ... but surely there is a better way?? Specifically, Topic "7633 readout drift" by Lop pol .... as my 7603 Scope has the same symptoms.
Re: 7633 readout drift

 

lop pol
11:07 am #147825

When powering on the scope from cold the readout is high by about half a graticule. After 3-5 minutes of warm up the readout drifts to the center of the top graticule. Is this normal for this to happen.

davehouse@...
5:12 pm #147842

No, it's supposed to be in the correct position as soon as the beam appears. Does it drift with the trace, or independently?

Also, do you have a cold spray? The easiest way to find out the culprit is to cool down individual components in the readout vertical signal path. I bet it's a semiconductor, maybe the 155-0020.

On Sun, May 13, 2018 at 06:26 pm, Jeff Urban wrote:


On Sun, May 13, 2018 at 05:30 pm, lop pol wrote:


It drifts independent of the trace.
Does that mean with an actual waveform displayed so you can see if the
vertical and horizontal are changing ? Just a flat like won't tell you for
sure.

If they are changing look at HV regulation or overall PS regulation. If it
really is only the readout the look for supplies specific to that system.

Hope it is something like a supply voltage or something, that subsystem is one
complex MF. If not, get ready for some fun and pack a lunch.
So far this is what I have figured out. the 5V line has an intermittent short. I replaced it. /g/TekScopes/photo/49110/0?p=Name,,,20,1,0,0
Z axis transistor Qwhatfreakingever /g/TekScopes/photo/49110/0?p=Name,,,20,1,0,0 was not connected to its base.
And I'm pretty sure R2527 (thermal balance) is bad. Just touching it causes the bottom readout to distort and jump to the middle of the screen. I swapped the readout board just to make sure and the issue still persisted. Tomorrow I will swap out the thermal balance resistor and go from there.
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