Date   

Re: Peter Keller CRT Articles and Book. WAS: Reworked Tek' Lit

 

Hi Colin,
This is not your fault. Quite the opposite.
I appreciate the link you provided as did Peter.
Peter was not aware of this site and he indicated to me that he would be contacting them to take it down if it violated his copyright.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Colin Herbert via groups.io
Sent: Saturday, November 14, 2020 4:33 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Peter Keller CRT Articles and Book. WAS: Reworked Tek' Lit

Well, I was just quoting from this message:

"Just DL the complete book in PDF at this site; https://archive.org/details/keller1991cathode-ray/mode/2up
It´s opensource so free for everyone :-)

René"

This was on Tekscopes a while ago:
https://groups.io/g/TekScopes/message/172365

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Roy Thistle
Sent: 13 November 2020 20:00
To: TekScopes@groups.io
Subject: Re: [TekScopes] Peter Keller CRT Articles and Book. WAS: Reworked Tek' Lit

On Fri, Nov 13, 2020 at 08:27 AM, Colin Herbert wrote:


It is open-source
but... is it?
Google Books still shows it as copyrighted Palisades Press... (which probably means Mr. Keller has the copyright?) It's also for sale on Amazon, through some used book reseller.













--
Dennis Tillman W7pF
TekScopes Moderator


Noisy/drifty S-6 head

Siggi
 

Hey y'all,

I just scored a Model 3 cart for my 7834 locally. After relocating the
scope and the modules I have from the floor, I played a little bit with my
7S12. Initially I had my S-52 in there with an S-4 sampler, just looking at
some SMA cables, got a rock solid trace.
I wanted to look at the SMA terminator I got with my NanoVNA, so I dropped
my S-6 sampler in there. With this sampler I see the signal just fine, only
it seems to be quite drifty or noisy.
I'm hoping this is a calibration issue of some sort, rather than a blown
sampling gate - or perhaps something downstream from the sampling gate.
Does anyone here have experience with this sort of thing?

Thanks,
Siggi


Re: Another A5 board repair attemp - help needed

Siggi
 

Hey Roger,

I guess that tears it. There has to be something wrong with either the DAC,
its data inputs, the load resistors or the MUXes. Not a bad bet that the
DAC's gone - alas.
I really don't think there's a chance that you have e.g. leakage current
due to electrolyte on the board (how did you clean it?), as pin 14 is
effectively at ground level.

Here's what I get:

Designator Voltage Value (Ohms) Current (mA)
R2026 1.035 1000 1.035
R2013 8.960 10000 0.896
R2011 0.660 4750 0.139
R2015 8.300 82500 0.101
R2014 8.300 221000 0.038
R2010 0.004 20000 0.000
R2012 0.002 10000 0.000

Pin 14 1.034 (mA) (Sum of R2013, R2015, R2014 - due to the setting of
R2010).

So Pin 14 is getting ~3% extra current, and the references are still ~8%
low. Since you've already pulled one of the MUXes, you might consider
pulling the others. Or you could just change the DAC and see whether that
fixes it.
There is a possibility that R2520/R2521 have drifted - though I'd be very
surprised. You can check their relative values by measuring the voltage
across them with e.g. a DMM with the scope running, they should be the same.

So, it seems within reason that the DAC is gone - alas. Looks like DAC312
is a direct replacement, in case you can't get the original AM6012.

Good luck and have fun,
Siggi

On Sat, Nov 14, 2020 at 3:41 PM Rogerio O <rodd414@gmail.com> wrote:

As I have posted before I shorted some U2521 pins while trying to measure
its outputs whith a scope probe.
Immediately after that the + 1.36V and -1.25V voltages references dropped
to values close to zero.
So I guess I have fried U2521.
For the ones following this topic I have uploaded an image of the voltages
at the DAC input to the album A5 repair attempt (
https://groups.io/g/TekScopes/album?id=256231).
Before doing that I made a continuity check on all traces of this resistor
divider and all were ok.
The measurements show that there is about 1mA of current and it is going
all to pin 14, but I don't known if this is how the circuit is supposed to
work.
I tried to check these values posted in old trends as images but
apparently they were were lost when this group moved so I will post the
values here as well.
+10V input --- 10.000V
R2026 --- 1.035V
R2013 --- 8.96V
R2011 --- 0.66V
R2015 --- 8.30V
R2014 --- 8.30V
R2010 (fully CCW - wiper contacting R2013) --- 0.004V
R2012 --- 0.002V







Special Offer from Peter Keller to TekScopes Members: The Cathode Ray Tube, Technology, History, and Applications"

 

In 2017 when I bought my copy of Peter Keller's definitive book on the CRT I
paid $70 for it.

1) PETER WAS VERY CLEAR: HE HAS NOT GIVEN ANYONE PERMISSION TO SCAN HIS BOOK
OR TURN IT INTO AN ELECTRONIC, DOWNLOADABLE, FILE (but he has made it
possible to buy it at a huge discount)
2) The 6-part, 36-page article that Bill Perkins scanned on the Tektronix
CRTs was originally published by the Tube Collectors Association which has
since disbanded. As far as Peter is concerned we may post it to our website.
It will then be accessible to more researchers and collectors there.
3) I (Dennis Tillman) also think this article should be posted to TekWiki.

AND NOW FOR THE VERY GOOD NEWS:
Peter's book is still available in hard cover and he has copies of to sell.
Because of recent interest in it from more than five members of TekScopes I
went out on a limb and asked if a discount would be available if I could
guarantee him an order of at least 10 copies of his book provided I did all
the work of collecting the funds and mailing the copies to our members. In
his reply (BELOW) he offered our members a huge discount. The cost would be
$40 + shipping if we order 10 copies or $30 + shipping for an order of 20
copies of his book. If there are 20 orders that will mean your copy will
cost less than half of what I paid for my copy. Also, I believe I can even
get him to autograph each copy.

If there are enough orders I will collect the funds and ship each order to
our members. In the meantime I will find out the most economical way to ship
these.

If you definitely want a copy of Peter's book contact me OFF-LIST at dennis
at ridesoft dot com and include your address. Once I know what the postage
will cost and how many orders we have I will know what the final price will
be for each of you.

Dennis Tillman W7pF

From: Peter Keller
Sent: Friday, November 13, 2020 9:25 PM
To: dennis@ridesoft.com <mailto:dennis@ridesoft.com>
Subject: RE: Inquiries about your book

Hi Dennis,
I have been selling them at $69.50 plus $6.00 shipping. For ten all shipped
to one address at one time I would be willing to sell them at $39.50 each
plus actual shipping cost. Ten copies would weigh about 25-30 pounds I
believe. Twenty copies would be $29.50 each plus shipping.

Peter


Re: Tek 475 Front Panel Ground Point

Michael W. Lynch
 

My 465B, 475 and 475A all have the grounding post in the ground socket. I also have a couple of 7000 series plug ins that have them as well. I guess I was just lucky to end up with so many?

--
Michael Lynch
Dardanelle, AR


Re: Another A5 board repair attemp - help needed

Rogerio O
 

As I have posted before I shorted some U2521 pins while trying to measure its outputs whith a scope probe.
Immediately after that the + 1.36V and -1.25V voltages references dropped to values close to zero.
So I guess I have fried U2521.
For the ones following this topic I have uploaded an image of the voltages at the DAC input to the album A5 repair attempt (https://groups.io/g/TekScopes/album?id=256231).
Before doing that I made a continuity check on all traces of this resistor divider and all were ok.
The measurements show that there is about 1mA of current and it is going all to pin 14, but I don't known if this is how the circuit is supposed to work.
I tried to check these values posted in old trends as images but apparently they were were lost when this group moved so I will post the values here as well.
+10V input --- 10.000V
R2026 --- 1.035V
R2013 --- 8.96V
R2011 --- 0.66V
R2015 --- 8.30V
R2014 --- 8.30V
R2010 (fully CCW - wiper contacting R2013) --- 0.004V
R2012 --- 0.002V


Photo Voltages at DAC divider.jpg uploaded #photo-notice

TekScopes@groups.io Notification <noreply@...>
 

The following photos have been uploaded to the A5 repair attempt album of the TekScopes@groups.io group.

By: Rogerio O


Re: 7A12 attenuator board clone

Göran Krusell
 

Mathematically it is not possible to compensate for this problem and the reason is that the dielectric constant is frequency dependent - and this is bad.
Göran


Re: Tek 475 Front Panel Ground Point

Colin Herbert
 

I have just undertaken a voyage of discovery amongst my various bits and pieces and not only do I have one of these, but it is shown in my 475A Service Manual as "Plug, Tip: W/Binding Post" in the "Accessories" section. Oddly enough, though, I can't (at present) find it in my 468 Manual, which come in two parts, nor in the Common Design Parts catalogues. I suppose that with the 475 that was your father's, there is one of these in the earth-point socket that I mentioned that both of my 475As have.

Now if only I could find the bits that I was actually looking for.....

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky
Sent: 14 November 2020 19:18
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 475 Front Panel Ground Point

Dave, Colin,

Thanks for the replies. I also found (and lost the auction for) a 475A on eBay that showed the ground wire adapter in a bag of "accessories" so it was clear that this was original equipment. Differential measurements seems a very likely suggestion considering that my father was a service engineer for a manufacturer of mass analysis and associated equipment when he got and used this scope.


Re: 7A12 attenuator board clone

Dave Wise
 

I saw this in my 1A7. I reduced the common-mode error by replacing one resistor in the attenuator with a smaller R in series with a parallel RC. Values were cut and try.

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Tom Lee via groups.io <tomlee=ee.stanford.edu@groups.io>
Sent: Saturday, November 14, 2020 12:53 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7A12 attenuator board clone

The "hook" that people have mentioned a couple of times is the nickname
for the step response artifact caused by a dispersive dielectric. If you
adjust the compensation so that the rising edge peaks at the same level
as the steady-state value, you find that the response sags in between.
There are ways to compensate for that effect to one degree or another,
but it's not trivial to do it well.

-- Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 11/13/2020 13:06, Martin Hodge wrote:
According to the manual, the 7A12 attenuator board is made of Polyphenylene Oxide. If one were to try to use a 7A12 with an FR4 attenuator, how would it's inferiority manifest on the screen? And what signal would one need to feed it to make it "fail"?

In case I didn't make it clear, this was a purely educational endeavor for me. I was curious to see what the difference would be, if any.





Re: Tek 475 Front Panel Ground Point

 

Dave, Colin,

Thanks for the replies. I also found (and lost the auction for) a 475A on eBay that showed the ground wire adapter in a bag of "accessories" so it was clear that this was original equipment. Differential measurements seems a very likely suggestion considering that my father was a service engineer for a manufacturer of mass analysis and associated equipment when he got and used this scope.


Added Folder /pickup devices for vey-low-frequency reception #file-notice

TekScopes@groups.io Notification <noreply@...>
 

snapdiode added folder /pickup devices for vey-low-frequency reception


#file-notice A scan of an old article #file-notice

snapdiode
 

I just scanned in something that looks like the structure inside the P6042 head.

I am puzzled why scanners don't have a "flip every other page" option, when you scan a book you have no choice but to flip it over every other page...


Re: Curve tracer as a power supply

 

With this problem, I always use my Variac to generate sufficient AC voltage to the input of any DUT, noting the minimum VAC it takes to activate the DUT.
Absolutely ZERO guesswork, when using this method.

Then I look over here for Amveco Toroid Transformers, which match (+/-) the required VAC (which I discovered on the Variac).
https://www.surplussales.com/class/inductor/toroidal.html

You can certainly select up to about 20% more VAC capability with no adverse effects, except for a little warmth in the PSU circuit.
Toroids have far less loss factor than E or C type transformers, therefore generate far less heat.

Menahem Yachad
CondorAudio
Jerusalem


Re: Tek 475 Front Panel Ground Point

Daveolla
 

At 10:25 PM 11/04/2020, you wrote:
I have two scopes of my father's, one 475 and one 2213. The ground point on the front panel of the 2213 is just a banana plug socket, but on the 475 the ground point is a knurled metal post (looks like nickel). This always puzzled me because the post could turn, but didn't seem to unscrew, and it is much too big to attach a ground clip from a probe, or do much of anything else with. Well, today I solved part of the mystery of this odd ground point: it's a separate banana plug with screw-down terminal!
lar part (assuming that it's a generic piece of kit) with little success, but I may not be using the right search terms.

Does anybody know if Tek shipped such an accessory as part of the stock 475?
Yup,I (banana plug with small knurled end) have one and it is listed in the Tek 468 Scope manual as; "adapter, Ground Wire .......134-0016-01"
So you finally decided to give the post a pull ......................sorry, I had been meaning to suggest that to you:(

Dave




Re: Tek 475 Front Panel Ground Point

Colin Herbert
 

I have two 475As and neither have anything like you describe. They both have an banana-socket earth-point just to the left of the bottom left screw holding the CRT bezel in place. However, I have a couple of 7000-series plugins (7A13 & 7A22) which have earthed metal binding-posts with banana-plug sockets, where the knurled "nut" will unscrew completely and expose a hole drilled laterally across the metal post. These two plug-ins are capable of differential measurement between two inputs and I would guess that this earth-point is necessary for differential measurements. Perhaps your father was attempting to do differential measurements using the two channels on the 475 with one channel switched to "invert". If you look up info on differential measurements and how to make the connections, it might be a bit clearer.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky
Sent: 05 November 2020 04:25
To: TekScopes@groups.io
Subject: [TekScopes] Tek 475 Front Panel Ground Point

I have two scopes of my father's, one 475 and one 2213. The ground point on the front panel of the 2213 is just a banana plug socket, but on the 475 the ground point is a knurled metal post (looks like nickel). This always puzzled me because the post could turn, but didn't seem to unscrew, and it is much too big to attach a ground clip from a probe, or do much of anything else with. Well, today I solved part of the mystery of this odd ground point: it's a separate banana plug with screw-down terminal!

I went on the web looking for any images of a Tek 475 with this banana plug in the ground port, and I can't find a single one. I don't know why this never occurred to me before now, except that the ground point is rarely mentioned in Tek documentation (it doesn't even get it's own numbered label in the 475 Operators Manual), and the knurled post doesn't photograph very noticeably, no more so than an empty banana plug socket. I suspect that my father added this (possibly generic) banana plug to his scope as some convenience of his own (not sure what that would be, though: I had to use pliers to loosen the knurled nut, and the revealed contact faces, post and hole show no obvious signs of use), but he didn't add a similar piece to his 2213, so I'm at a loss for a sensible explanation.

I've tried to search Amazon for a similar part (assuming that it's a generic piece of kit) with little success, but I may not be using the right search terms.

Does anybody know if Tek shipped such an accessory as part of the stock 475?


Re: Peter Keller CRT Articles and Book. WAS: Reworked Tek' Lit

Colin Herbert
 

Well, I was just quoting from this message:

"Just DL the complete book in PDF at this site; https://archive.org/details/keller1991cathode-ray/mode/2up
It´s opensource so free for everyone :-)

René"

This was on Tekscopes a while ago:
https://groups.io/g/TekScopes/message/172365

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Roy Thistle
Sent: 13 November 2020 20:00
To: TekScopes@groups.io
Subject: Re: [TekScopes] Peter Keller CRT Articles and Book. WAS: Reworked Tek' Lit

On Fri, Nov 13, 2020 at 08:27 AM, Colin Herbert wrote:


It is open-source
but... is it?
Google Books still shows it as copyrighted Palisades Press... (which probably means Mr. Keller has the copyright?)
It's also for sale on Amazon, through some used book reseller.


Re: Peter Keller CRT Articles and Book. WAS: Reworked Tek' Lit

Tam Hanna
 

Hello Dennis,

I have tried to e-mail you offlist multiple times asking for the dude's contact data, but got nothing.


Can you please send it to me?


Tam

--
- - - - -
With best regards
Tam HANNA

Enjoy electronics? Join 13500 followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/


Re: Another A5 board repair attemp - help needed

Siggi
 

Þann lau., 14. nóv. 2020 kl. 05:32 skrifaði Rogerio O <rodd414@gmail.com>:

Since I will have to wait for the Mouser parts to arrive, I intend to
follow your suggestion to measure the voltages drop across the DAC
resistors.
Can I turn the scope on without U2521/U2420 soldered in place?

The only damage that could happen is CRT burn. If the beam intensity is
still under control or low/none, you’re fine. If the beam is too bright, it
helps to defocus it, and you can always turn down the CRT bias.


Re: 7L5 Res shaft encoder

Jean-Paul
 

9401 - 9420 of 182459