Date   
Re: 11801 NVRAM

Albert Otten
 

On Tue, Sep 17, 2019 at 12:43 AM, Reginald Beardsley wrote:


I am reporting what the frequencies of the trigger and ramp generated by the
33622A are and what the time/division of the 11801 is set to. The 33622A
frequencies are accurate to more digits than I have shown. ~1.1 ns is the
difference in the length of the trigger clock period and the ramp period. The
33622A is *much* more stable than the 11801 clock.
OK Reg, but I still can't understand how this would work.
I suppose each trigger event results in a sample. At each trigger event the position on the ramp advances 1.1 ns when compared to the previous trigger event. Over 1024 events this advances the position over about 1.1 us. Meanwhile there is also a total advance of 10 ps in the position of the sampling event due to the increases of delay between sample and trigger event; but 20 ps is negligible compared to 1.1 us. So I expect you can see only 1/9 fraction of the total ramp, which would also run vertically.
In my own experiment I found about 10 ns difference between required periods.

[BTW w.r.t. sweep jitter: this is not related to the blinking light at the sampling head, what has been recognized as cause of slight sweep jitter?]

Albert

Re: Excess scopes (7934, 7603, 468, 465)

Jason A.
 

Hi Paul,

I'm trying to figure out if a road trip is in my future. I'm patient if you do have pics.

Thanks and best regards,

Jason

Re: Tektronix 7854 Digitization Issue

 

On Tue, Sep 17, 2019 at 01:40 PM, Albert Otten wrote:


But I think your suggested remedy is not working. The Z-axis blanking is
itself a result of internal signal. The only logical output of the Z-axis
circuit is the GSF signal which inhibits digitizing/storage of extreme Y
values. During retrace there must be some "inhibit" signal active which
prevents digitizing/storage during retrace.
It's won't be easy I think to pinpoint the cause. I spent a few minutes
reading the Theory of Operation and looking at some diagrams, but oh boy!
I'd expect what you mention, Albert, but I have to confess that one of my 7854's was exhibiting the exact same behaviour when I first got it and I'm sure slightly adjusting one of the pots on the Z-axis pcb did the trick... Of course, I don't remember exactly which one... Z-axis had to be adjusted anyway and the problem was gone at the same time.
It'll be interesting to hear from the OP.

Raymond

Re: Tektronix 7854 Digitization Issue

Albert Otten
 

On Tue, Sep 17, 2019 at 03:03 AM, Raymond Domp Frank wrote:


It acquires waveforms, but it's as though it's acquiring two different
waves, one at the correct frequency, and one approximately 1/5 the period.
I posted a video to YouTube showing an acquisition, you can clearly see
another superimposed portion of the wave across the entire sweep.
The "low frequency" that you see is actually the retrace (return of beam to
left of screen). Have a look where it "ends" at the right side of the screen:
Always where the real trace stops, so it's actually the starting point for the
retrace. It should normally be invisible but blanking isn't set correctly for
the digitisation.
It's likely that adjusting the "grid bias/blanking" for the digitisation part
will solve your problem so check and if necessary adjust Z-axis levels. The
Z-axis circuits are on the board mounted at the back, where the GPIB and
battery backup connections are. It's not a dangerous adjustment in the sense
that you may/will lose calibration.
---
Raymond
Hi Raymond,

I agree with your interpretation, retrace samples appear in the acquired waveform. But I think your suggested remedy is not working. The Z-axis blanking is itself a result of internal signal. The only logical output of the Z-axis circuit is the GSF signal which inhibits digitizing/storage of extreme Y values. During retrace there must be some "inhibit" signal active which prevents digitizing/storage during retrace.
It's won't be easy I think to pinpoint the cause. I spent a few minutes reading the Theory of Operation and looking at some diagrams, but oh boy!

Albert

Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

Chuck Harris
 

They were loaded with oil/paper capacitors, known as
bumble bee type capacitors... all leaky, both physically,
and electrically.

They were also loaded with 20uf/20uf - 450V Sprague FP
can type capacitors... one for each tube's screen. All
leaky.

And, they had wafer switches, which were often sprayed to
dripping by some user at some point.

The HV was in an oil filled can, which would leak if the
scope was stored on its side... but shouldn't if it was
stored upright. The ceramic insulators were the seal.

-Chuck Harris

Dave Seiter wrote:

What kind of oil was used? I ask because one of mine (I think the 511a) seemed like it was filled with wax, or at least what leaked out long ago looks/feels like wax. What was the reason for burying the HV in oil? One of these days I'm going to have to open both of them up because neither works.
On Sep 16, 2019, at 3:13 PM, Dave Wise <david_wise@...> wrote:

< The vertical amplifier, and attenuator wasn't calibrated, so to make things work, you adjusted the vertical amplifier variable attenuation to exactly fit the waveform on the graticule lines. Then you switched the vertical input to the calibrator, and adjusted it to match the same graticule lines... reading the peak-peak voltage off of the calibrator's pointer dial.>

Thanks for explaining that so clearly. I suppose that using the graticule as a transfer standard was a good idea back when the amp and CRT deflection were not so linear.
I used to think "calibrated graticule" was just marketing. I didn't realize it was an inversion of methodology.

Still, if they gave me one now, I'd be happy to fix it and play with it, oil can and all.

Dave Wise

Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

Tom Li
 

Raymond Domp Frank said,
I'm pretty sure it is *not* (compatible with) a Lemo connector: The "Sealectro" has an
internal "shim" that the Lemo doesn't have, the Lemo has an "outward dent" in the rim
which the 454's doesn't have (it has one in the teflon center body) and the bushings
form an equilateral triangle in the 454's, whereas the Lemo 303's contacts as per the
catalog drawing don't.
No worries. I think your assessment is indeed correct, I don't think it's even
worth trying, so LEMO model 303 is not compatible with Sealectro 950-0019-86,
I've canceled the order.

The biggest problem is that, in the current catalog from Sealectro, it doesn't
even have a 950 prefix, it seems the series has been permanently discontinued
and there is no information about substitute. I went to Q-service's website as
suggested by Bruce as well, but it requires dedication to find the part in the
huge listings, not to mention the multi-week international shipping.

Now I decide to replace the power cord with a generic one with a DIN connector.
The power cord is not a impedance-controlled coax, replacing it should be straightforward,
getting a shielded cord should work well.

Meanwhile, if anyone has ideas about potentially compatible parts, I would
purchase and test them. I think it may help someone else in the future, my
thread seems to be the only discussion about the 3-pin power connector I
can find on the entire web.

Tom Li

Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

 

The Tek Electro-Mechanical Common Design Parts Catalog (Jan 1989) on page 11-14 "Circular Connectors Multipin - Receptacle" describes it as:
Contacts: 3 Female
Thread Size: 0.354"
Special Features: Snap Lock with Index Mark
Cost: $8.90
Code: CS (meaning Customer Service Replacement Item not used in a current production instrument)

Neither the Common Design Parts Catalog nor the 454 Service Manual has any manufacturer information. This comes as a surprise to me.

Dennis Tillman W7PF

-----Original Message-----
From: Raymond Domp Frank
Sent: Monday, September 16, 2019 4:14 PM

I have 454 manual document 070-0617-00.

The power sockets are 2 pieces 131-0438-00, shown as part 84 in fig. 1, "Front".
The parts list shows them as "CONNECTOR, 3 contact, female".
In the schematic diagram they can be seen as "U123B" and "J123" in dwg 14 In the mechanical parts list they are shown as "J1238" and "J1239", which makes more sense.

Raymond




--
Dennis Tillman W7PF
TekScopes Moderator

Re: Tektronix 7854 Digitization Issue

 

The "low frequency" that you see is actually the retrace (return of beam to left of screen).
At the beginning of your video, the retrace is quite visible as the low-frequency waveform. Subsequent acquisitions show artefacts caused by the fact that the digitisation system wasn't designed to show the retrace as a separate trace so it's just interfering.

Raymond

Re: Tektronix 7854 Digitization Issue

 

It acquires waveforms, but it's as though it's acquiring two different
waves, one at the correct frequency, and one approximately 1/5 the period.
I posted a video to YouTube showing an acquisition, you can clearly see
another superimposed portion of the wave across the entire sweep.
The "low frequency" that you see is actually the retrace (return of beam to left of screen). Have a look where it "ends" at the right side of the screen: Always where the real trace stops, so it's actually the starting point for the retrace. It should normally be invisible but blanking isn't set correctly for the digitisation.
It's likely that adjusting the "grid bias/blanking" for the digitisation part will solve your problem so check and if necessary adjust Z-axis levels. The Z-axis circuits are on the board mounted at the back, where the GPIB and battery backup connections are. It's not a dangerous adjustment in the sense that you may/will lose calibration.

Also, the rendered text gets wonky during an acquisition.
That is perfectly normal during acquisition.

Raymond

Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

Dave Seiter
 

What kind of oil was used? I ask because one of mine (I think the 511a) seemed like it was filled with wax, or at least what leaked out long ago looks/feels like wax. What was the reason for burying the HV in oil? One of these days I'm going to have to open both of them up because neither works.

On Sep 16, 2019, at 3:13 PM, Dave Wise <david_wise@...> wrote:

< The vertical amplifier, and attenuator wasn't calibrated, so to make things work, you adjusted the vertical amplifier variable attenuation to exactly fit the waveform on the graticule lines. Then you switched the vertical input to the calibrator, and adjusted it to match the same graticule lines... reading the peak-peak voltage off of the calibrator's pointer dial.>

Thanks for explaining that so clearly. I suppose that using the graticule as a transfer standard was a good idea back when the amp and CRT deflection were not so linear.
I used to think "calibrated graticule" was just marketing. I didn't realize it was an inversion of methodology.

Still, if they gave me one now, I'd be happy to fix it and play with it, oil can and all.

Dave Wise

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris
Sent: Monday, September 16, 2019 2:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

The old 500 series worked quite differently from what
became the standard analog scope interface, the 545.

The vertical amplifier, and attenuator wasn't calibrated,
so to make things work, you adjusted the vertical amplifier
variable attenuation to exactly fit the waveform on the
graticule lines. Then you switched the vertical input
to the calibrator, and adjusted it to match the same
graticule lines... reading the peak-peak voltage off of
the calibrator's pointer dial.

The horizontal time was similarly odd.... but at least it
was calibrated to the graticule.

The main time switch selected the decade you were in: 1000us,
100us, 10us, 1us, 0.1us per cm. The secondary time switch
was a two dial multiplier, that had 0-10 on one dial, and 0-0.9
on the second. Typically, you adjusted the timing so that
you had one cycle on the graticule, and read the time off of
the dials.

-Chuck Harris

OBTW, the HV section was in a sealed can full of oil. Which
was a good thing for the bumble bee capacitors in it, but not
too convenient when a 5642 rectifier burned out. You unscrew
the HV insulators, to keep the pressure down, unsolder the
can lid, and extract the HV section. It is exactly the same
configuration as all of the later 500 series, only the HV
transformer is the much larger 2.75" W5 E core... and ran at
400Hz, as I recall... maybe 1KHz.

Dave Wise wrote:
Closest I got was high school (Benson Polytechnic in Portland OR) in the early 70's, where one electronics classroom had a 514D in a back corner. I always felt sorry for the poor old thing, which was never touched as far as I know. Also covetous; but the teacher wouldn't give it up. It was the best instrument in the room, our assigned tools being RCA service-grade boxes.

Dave Wise





Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

 

This is getting embarrassing, although it's only 2:00 AM where I live:

Correction of my correction a few moments ago:

It should read

"The rim of the sockets on one of my 454's is marked "Sealectro" and "950-0019-86", *not* "950-0019-00".

Raymond

Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

 

Correction:
The rim of the sockets on one of my 454's is marked "Sealectro" and "950-0019-86", *not* "950-0019-86".

Raymond

Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

 

TekWiki is unable to confirm it either, it says "The 015-0073-00 (power supply) has
a 3-pin probe power connector (Sealectro 55-850-0018-98?)", note the question mark,
and worse, I was unable to find that Sealectro part.
The rim of the sockets on one of my 454's is marked "Sealectro" and "950-0019-00".

After some researches in the mailing list archive, currently I highly suspect it's a
LEMO connector, model 303. I've already ordered one EGG.00.303.CLL. I'll update
the thread and report back when my package arrives.
I'm pretty sure it is *not* (compatible with) a Lemo connector: The "Sealectro" has an internal "shim" that the Lemo doesn't have, the Lemo has an "outward dent" in the rim which the 454's doesn't have (it has one in the teflon center body) and the bushings form an equilateral triangle in the 454's, whereas the Lemo 303's contacts as per the catalog drawing don't. I haven't checked exact measures and
unfortunately, I cant suggest a number nor supplier for the 454's sockets.

The later 4-pin probe power sockets are Lemo.

Raymond

Re: 561B Recapping

David Holland
 

Yes, but I'd like to have some replacements in mind... They won't
last forever, and I'm eyeing restoring some assorted plugins of
unknown status, and so, I'd like to have the mainframe in a known
healthy state...

I've also a RM567 sitting on the shelf that is in definite unknown
status that may (or not) need similar diagnosis...

There are approximate current limits in the IRB for the 561A (and by
proxy the 561B) I suppose I can putter around in LTSpice, read some
linear PSU design guides, and make some slightly less wild guesses..

On Mon, Sep 16, 2019 at 2:13 PM widgethunter via Groups.Io
<tubesnthings=aol.com@groups.io> wrote:

If it aint broke don't fix it!!!Running several 561As & 565 in original condition with NO issues.That is the norm for 500 series gear.Bernie Schroder



-----Original Message-----
From: Glydeck via Groups.Io <glydeck=aol.com@groups.io>
To: TekScopes <TekScopes@groups.io>
Sent: Sun, Sep 15, 2019 5:15 pm
Subject: Re: [TekScopes] 561B Recapping

I would be interested as well. — George
On Sep 15, 2019, at 1:17 PM, David Holland <david.w.holland@...> wrote:

Anyone recapped a Tektronix 561B, and have some pointers for capacitor
replacement specifications? (ESR/DF & ripple current ratings
particularly)

Looking up the Tektronix part numbers will lead to NSN numbers, which
will give original manufacturers, (Sprague/Mallory), and purported
original part numbers, that I can not find references to.

There's nothing I'm aware of specifically wrong with the scope at the
moment, other than 47 years on those caps - based on the 1972 date
codes, and a serial # in the B19xxx range.

There is also 2 (of 3) tantalum capacitors that don't seem to be
de-rated particularly well (C11 & C31). - (Yes, they look like
tantalum, the NSN's say they are tant., and their tiny physical size
strongly implies it as well.)

I've a DER DE-5000 and a HV supply (Eico 950B) so I could pull them
and measure DF/ESR/leakage/etc to my hearts content, but if I'm going
to remove them, I'd just as soon put new caps back in circuit.

Suggestions? Comments? Cries of Derision?

Thanks,

David






Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

Tom Li
 

Thanks for everyone's response.

After some researches in the mailing list archive, currently I highly suspect it's a
LEMO connector, model 303. I've already ordered one EGG.00.303.CLL. I'll update
the thread and report back when my package arrives.

Tom Li.

Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

 

I have 454 manual document 070-0617-00.

The power sockets are 2 pieces 131-0438-00, shown as part 84 in fig. 1, "Front".
The parts list shows them as "CONNECTOR, 3 contact, female".
In the schematic diagram they can be seen as "U123B" and "J123" in dwg 14
In the mechanical parts list they are shown as "J1238" and "J1239", which makes more sense.

Raymond

Tektronix 7854 Digitization Issue

Kyle Rhodes
 

Hi all,

I've got a wonderful 7854 acquired from a fellow list member, but I'm
having an issue with it. The digitization / storage function is not
working properly. Allow me to explain:

It acquires waveforms, but it's as though it's acquiring two different
waves, one at the correct frequency, and one approximately 1/5 the period.
I posted a video to YouTube showing an acquisition, you can clearly see
another superimposed portion of the wave across the entire sweep.

https://www.youtube.com/watch?v=vUq_e4OoAPA

The samples average out a bit if you run 10 or 100 acqs, but obviously it
doesn't result in a nice digitized waveform.

Also, the rendered text gets wonky during an acquisition. I'm not sure if
this is normal, or maybe it's related to the issue?

It's as though the time axis is not correlated properly with the Y axis
sample. Has anyone else encountered such a problem? This is a complex
unit, and before I spent many hours digging through the documentation and
learning how it works, I thought I'd ask for some starting points. Time is
money, and while I love working on this stuff, my day job involves using my
collection of equipment to produce other goods, so the less time spent
troubleshooting, the better. :)


Thanks,
Kyle

Re: 11801 NVRAM

Reginald Beardsley
 

Albert,

I am reporting what the frequencies of the trigger and ramp generated by the 33622A are and what the time/division of the 11801 is set to. The 33622A frequencies are accurate to more digits than I have shown. ~1.1 ns is the difference in the length of the trigger clock period and the ramp period. The 33622A is *much* more stable than the 11801 clock.

At 512 & 1024 samples the 11801 will allow 1 ps/div. As you increase the number of samples, the minimum time per division increases. The limit is 10 femtoseconds interval between adjacent sample points. So as you increase the number of points in a sweep, the minimum time per division increases.

With a 100 kHz ramp displayed with 1024 points spaced at intervals of 10 fs, the display is only showing 1 out of every million possible samples along the ramp.

With 1024 samples at 10 fs intervals, it makes 4 obvious sweeps with 200 fs jitter between the start of each sweep. It generally shifts slightly every 4 sweeps and 4 sweeps take place faster than I can count. When the OXO heater turns on it moves like mad for about 10-20 seconds before it settles down again. At 5120 samples at 10 fs intervals it makes 2 obvious sweeps. The jitter is tough to estimate at 5 ps/div. but looks to be around 200 fs. There is some indication that there might be 32 sweeps in a set, but I have not been able to find a way to verify that.

Have Fun!
Reg

Re: Identify the 3-pin Sealectro power Connector from 454 scope for P6045 probe

Dave Daniel
 

Well, the manufacturer and part numbers are on the mating connectors, so one can tell what they are directly. They are both Sealectro (which is what the OP wrote) with different part numbers for each half. I can see the part numbers, but I can't read them. I'll need to find a magnifier. They are not Lemo connectors.

I don't see the usual Tektronix-to-actual manufacturer list in the manual, and the manual is a bit confusing. I have been trying to decipher it. The Sealectro connectors seem to be called out as single-conductor connectors (item ref. no. 37), but that can't be right. It is shown on the schematic (J60) and shown as a three-pin round connector.

I'm confused. I also have one eye temporarily out of commission,so that is not helping matters.

DaveD

On 9/16/2019 5:48 PM, Dennis Tillman W7PF wrote:
Am I missing something?
Did anyone look in the service manual for the part number and the manufacturer code number?
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of uniacke1 via Groups.Io
Sent: Monday, September 16, 2019 1:32 PM

Any chance it's a 3 pin LEMO variant? Tek used these in other probes as well, e.g. P6407
http://w140.com/tekwiki/wiki/LEMO_S-series_connector
catalog:

http://w140.com/lemo_unipole_multipole.pdf



Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

Dave Wise
 

< The vertical amplifier, and attenuator wasn't calibrated, so to make things work, you adjusted the vertical amplifier variable attenuation to exactly fit the waveform on the graticule lines. Then you switched the vertical input to the calibrator, and adjusted it to match the same graticule lines... reading the peak-peak voltage off of the calibrator's pointer dial.>

Thanks for explaining that so clearly. I suppose that using the graticule as a transfer standard was a good idea back when the amp and CRT deflection were not so linear.
I used to think "calibrated graticule" was just marketing. I didn't realize it was an inversion of methodology.

Still, if they gave me one now, I'd be happy to fix it and play with it, oil can and all.

Dave Wise

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris
Sent: Monday, September 16, 2019 2:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest

The old 500 series worked quite differently from what
became the standard analog scope interface, the 545.

The vertical amplifier, and attenuator wasn't calibrated,
so to make things work, you adjusted the vertical amplifier
variable attenuation to exactly fit the waveform on the
graticule lines. Then you switched the vertical input
to the calibrator, and adjusted it to match the same
graticule lines... reading the peak-peak voltage off of
the calibrator's pointer dial.

The horizontal time was similarly odd.... but at least it
was calibrated to the graticule.

The main time switch selected the decade you were in: 1000us,
100us, 10us, 1us, 0.1us per cm. The secondary time switch
was a two dial multiplier, that had 0-10 on one dial, and 0-0.9
on the second. Typically, you adjusted the timing so that
you had one cycle on the graticule, and read the time off of
the dials.

-Chuck Harris

OBTW, the HV section was in a sealed can full of oil. Which
was a good thing for the bumble bee capacitors in it, but not
too convenient when a 5642 rectifier burned out. You unscrew
the HV insulators, to keep the pressure down, unsolder the
can lid, and extract the HV section. It is exactly the same
configuration as all of the later 500 series, only the HV
transformer is the much larger 2.75" W5 E core... and ran at
400Hz, as I recall... maybe 1KHz.

Dave Wise wrote:
Closest I got was high school (Benson Polytechnic in Portland OR) in the early 70's, where one electronics classroom had a 514D in a back corner. I always felt sorry for the poor old thing, which was never touched as far as I know. Also covetous; but the teacher wouldn't give it up. It was the best instrument in the room, our assigned tools being RCA service-grade boxes.

Dave Wise