Date   

Re: Coketron - the "Real" Story from Peter Keller :) :) :)

 

My copy of the book just arrived (thanks Dennis!) and I see that I misunderstood how the Coketron was constructed. I had thought that the cathode and deflection plates were inserted into the neck of the Coke bottle, but they are actually contained in their own cylindrical envelope that is merely joined to the mouth of the Coke bottle. That also goes some way toward explaining why they had difficulty with the glass-to-glass joint (though I wonder why they didn't make the other envelope from Coke bottle glass. I suppose that the glass used for the envelope has specific material properties to make a good seal around the metal pins, or something similar)


Re: Coketron - the "Real" Story from Peter Keller :) :) :)

Michael A. Terrell
 

Glass bottles were half gallon, not two liter.

On Fri, Jan 15, 2021 at 9:01 AM Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Peter Keller asked me to pass this along to the group.

I'm sure he was smiling the entire time he wrote it.

Dennis Tillman W7pF



I guess it is time for the real story of the Coketron to be exposed.



The Coketron was originally developed for the cost reduction of the 545-B
with the new 545-C [ 545-C nomenclature - C for "Cokescope" ].



Advantages of the "Cokescope" included:

1. Lower material cost - Coke bottles only cost a few cents vs. several
dollars for CRT bulbs.

2. Independence from on-time supply issues caused by labor strikes at
Lancaster Glass and periodic flooding of the Corning Glass plant by the
nearby Chemung River. Coke bottles were always available anywhere.

3. Added employee benefits at Tek - the Coke bottles had to be emptied
by the bulb prep group before use.



The disadvantages that caused the program to be cancelled were pattern
distortions and how-the-heck do you paint the accelerator helix on the
double reentrant curve of the bottle? Also, the glass 2-liter Coke bottles
necessary to better fill the big round hole in the 545-C front panel were
not yet perfected. 2-liter plastic Coke bottles were tried but they tended
to sag into strange shapes at bake-out.



Seriously though, Tom Lee was closest.

Two Coketrons were made several years apart in the Engineering Tube Lab
just
to show that it could be done. The first used a T3100 or T3160 gun and
worked surprisingly well. I can remember it displaying the crosshatch
pattern generated by the CRT engineering B2 test sets. Unfortunately, the
tube later rolled off a bench and failed the impromptu drop test. I believe
it was during a lab move.



The second tube used a T2110 gun and suffered a cracked bulb due to thermal
coefficient mismatch of the glasses during processing. This was repaired
and
became the tube pictured in my book. This one did not have phosphor on the
screen but glass fluorescence would usually suffice to display a trace.
Both
tubes did have complete electron guns with deflection plates. I can't
recall
the second tube actually being operated but excessive gas levels due to
little or no bake-out because of the TC mismatch might have been the
reason.
I remember it was mainly constructed for photos since we had none of the
first tube.



There you have the rest of the stories. Take your pick!



All of this was 30+ years ago so memories are a little fuzzy.



Peter Keller









Re: Coketron - the "Real" Story from Peter Keller :) :) :)

Roy Thistle
 

On Fri, Jan 15, 2021 at 06:28 AM, Tom Lee wrote:


makes me want to go and build one
Not to imply one thinks it is... but, it is not so easy... even if one's institution funds a glass fabrication shop (and many no longer do)... and has a skilled scientific glassblower (Dodos may be rarer.)... and one has a source of electron gun assemblies... and one has available high vacuum technology.
Back then electron gun assemblies (basically, the entire rear end of a CRT: from pins, to electron gun... including a getter... and a nipple for evacuation) ... those assemblies were readily available... although sourcing assemblies with deflection plates for electrostatic deflection would probably have been harder. (... electron gun assemblies for CRTs using electromagnetic deflection were being manufactured in the 10s of millions?... specialty ones for electrostatic deflection, not so much.)
Fabricating a reasonable electron gun assembly would probably be an order of magnitude higher, and probably a project breaker too, for most.
Given one has access to the "men and materials," it is not so easy as chucking up a coke bottle on one end of a glass lathe, and a crt assembly on the other end... and then having a go at it with a double headed torch.
There is a technology of skill, and materials, to making successful glass to glass seals that are sufficiently vacuum tight and sufficiently stress free that the seal lasts.
And what about a phosphor... is the visible cathodoluminescence of soda lime glass alone sufficient, given it is the bottom of a bottle being struck.
But about these things... maybe, we shall see.


Tektronix 214 Storage Scope

Carl Hallberg
 

Hi Group,
Some years ago I got 2 basket case scopes.  The problems involved a leaky diode and bad trigger chip in one and for both I decided to remove the batteries, and not have them internal to the scope.  They had been leaking and I didn't want anymore damage.  The regulator is a shunt type because a series regulator would have a voltage loss across it.  It is good to plug it into the cigar lighter of a car or use a gel cell battery, but no longer uses the internal charging.  I sold one of them to Jon Batters, who I miss on Tekscopes.  Talked to him on the phone couple of times.  Good conversations.  The 214 nice little scope but only 500KHz.

Carl Hallberg (W9CJH)

https://groups.io/g/TekScopes/album?id=259407


Photo Notifications #photo-notice

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

The following photos have been uploaded to the Tektronix 214 storage scope album of the TekScopes@groups.io group.

By: Carl Hallberg


The following photos have been uploaded to the Tektronix 214 storage scope album of the TekScopes@groups.io group.

By: Carl Hallberg


Photo Notifications #photo-notice

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

Carl Hallberg added the album Tektronix 214 storage scope: Converted internal battery operation to external 12 Volts source #Tektronix214


The following photos have been uploaded to the Tektronix 214 storage scope album of the TekScopes@groups.io group.

By: Carl Hallberg


Re: [Resurrecting a Tek 485] Sweep not from left to right ?

Tom Lee
 

In the old days of crt TVs, it was fun to swap connections on the deflection yoke. Upside down, right-to-left TV? Nanoseconds of hilarity for kids.

Simpler times.

--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 1/15/2021 08:18, marcosjl31@gmail.com wrote:
that one was an easy fix.




Re: [Resurrecting a Tek 485] Sweep not from left to right ?

marcosjl31@...
 

that one was an easy fix.


Re: Groups.io price increase?

Jean-Paul
 

https://beta.groups.io/g/main/topic/79024735#27191

Change appears to apply only to upgrade in group sizes or type after mid January.

Do existing rates stay the same?

Jon


Re: Groups.io price increase?

Jean-Paul
 

Toby are there alternative forums sites or group hosts like groups.io?
What is the cost per member per year now vs increased?

Jon


Re: Groups.io price increase?

toby@...
 

On 2021-01-15 8:52 a.m., Jean-Paul wrote:
Dennis Good points, please can you calculate the cost/ year now or 2020 vs the new cost increase?
To be clear, I find the price change disappointing, disgusting and
opportunistic. Groups.io has many economies of scale that are not
available to individual mailing lists.

No doubt they have calculated likely costs of people moving off the
platform and have cynically priced accordingly. There are plenty of
precedents for this among rent seeking services...

--T


How many members do we have?

Jon






Re: Coketron - the "Real" Story from Peter Keller :) :) :)

Tom Lee
 

Thus makes me want to go and build one and hook it up to my 545!

Sent from my iThing, so please forgive the terseness and typos.

On Jan 15, 2021, at 6:01, "Dennis Tillman W7pF" <dennis@ridesoft.com> wrote:

Peter Keller asked me to pass this along to the group.

I'm sure he was smiling the entire time he wrote it.

Dennis Tillman W7pF



I guess it is time for the real story of the Coketron to be exposed.



The Coketron was originally developed for the cost reduction of the 545-B
with the new 545-C [ 545-C nomenclature - C for "Cokescope" ].



Advantages of the "Cokescope" included:

1. Lower material cost - Coke bottles only cost a few cents vs. several
dollars for CRT bulbs.

2. Independence from on-time supply issues caused by labor strikes at
Lancaster Glass and periodic flooding of the Corning Glass plant by the
nearby Chemung River. Coke bottles were always available anywhere.

3. Added employee benefits at Tek - the Coke bottles had to be emptied
by the bulb prep group before use.



The disadvantages that caused the program to be cancelled were pattern
distortions and how-the-heck do you paint the accelerator helix on the
double reentrant curve of the bottle? Also, the glass 2-liter Coke bottles
necessary to better fill the big round hole in the 545-C front panel were
not yet perfected. 2-liter plastic Coke bottles were tried but they tended
to sag into strange shapes at bake-out.



Seriously though, Tom Lee was closest.

Two Coketrons were made several years apart in the Engineering Tube Lab just
to show that it could be done. The first used a T3100 or T3160 gun and
worked surprisingly well. I can remember it displaying the crosshatch
pattern generated by the CRT engineering B2 test sets. Unfortunately, the
tube later rolled off a bench and failed the impromptu drop test. I believe
it was during a lab move.



The second tube used a T2110 gun and suffered a cracked bulb due to thermal
coefficient mismatch of the glasses during processing. This was repaired and
became the tube pictured in my book. This one did not have phosphor on the
screen but glass fluorescence would usually suffice to display a trace. Both
tubes did have complete electron guns with deflection plates. I can't recall
the second tube actually being operated but excessive gas levels due to
little or no bake-out because of the TC mismatch might have been the reason.
I remember it was mainly constructed for photos since we had none of the
first tube.



There you have the rest of the stories. Take your pick!



All of this was 30+ years ago so memories are a little fuzzy.



Peter Keller








Re: Coketron - the "Real" Story from Peter Keller :) :) :)

Tom Lee
 

Sent from my iThing, so please forgive the terseness and typos.

On Jan 15, 2021, at 6:01, "Dennis Tillman W7pF" <dennis@ridesoft.com> wrote:

Peter Keller asked me to pass this along to the group.

I'm sure he was smiling the entire time he wrote it.

Dennis Tillman W7pF



I guess it is time for the real story of the Coketron to be exposed.



The Coketron was originally developed for the cost reduction of the 545-B
with the new 545-C [ 545-C nomenclature - C for "Cokescope" ].



Advantages of the "Cokescope" included:

1. Lower material cost - Coke bottles only cost a few cents vs. several
dollars for CRT bulbs.

2. Independence from on-time supply issues caused by labor strikes at
Lancaster Glass and periodic flooding of the Corning Glass plant by the
nearby Chemung River. Coke bottles were always available anywhere.

3. Added employee benefits at Tek - the Coke bottles had to be emptied
by the bulb prep group before use.



The disadvantages that caused the program to be cancelled were pattern
distortions and how-the-heck do you paint the accelerator helix on the
double reentrant curve of the bottle? Also, the glass 2-liter Coke bottles
necessary to better fill the big round hole in the 545-C front panel were
not yet perfected. 2-liter plastic Coke bottles were tried but they tended
to sag into strange shapes at bake-out.



Seriously though, Tom Lee was closest.

Two Coketrons were made several years apart in the Engineering Tube Lab just
to show that it could be done. The first used a T3100 or T3160 gun and
worked surprisingly well. I can remember it displaying the crosshatch
pattern generated by the CRT engineering B2 test sets. Unfortunately, the
tube later rolled off a bench and failed the impromptu drop test. I believe
it was during a lab move.



The second tube used a T2110 gun and suffered a cracked bulb due to thermal
coefficient mismatch of the glasses during processing. This was repaired and
became the tube pictured in my book. This one did not have phosphor on the
screen but glass fluorescence would usually suffice to display a trace. Both
tubes did have complete electron guns with deflection plates. I can't recall
the second tube actually being operated but excessive gas levels due to
little or no bake-out because of the TC mismatch might have been the reason.
I remember it was mainly constructed for photos since we had none of the
first tube.



There you have the rest of the stories. Take your pick!



All of this was 30+ years ago so memories are a little fuzzy.



Peter Keller








Re: [Resurrecting a Tek 485] Sweep not from left to right ?

Roger Evans
 

The most likely explanation is that the two wires from the X amplifier board to the CRT X deflection plates .have been swapped over by mistake. Take care in correcting this, the pins on the CRT do like being bent and then straightened.

Regards,

Roger


Coketron - the "Real" Story from Peter Keller :) :) :)

 

Peter Keller asked me to pass this along to the group.

I'm sure he was smiling the entire time he wrote it.

Dennis Tillman W7pF



I guess it is time for the real story of the Coketron to be exposed.



The Coketron was originally developed for the cost reduction of the 545-B
with the new 545-C [ 545-C nomenclature - C for "Cokescope" ].



Advantages of the "Cokescope" included:

1. Lower material cost - Coke bottles only cost a few cents vs. several
dollars for CRT bulbs.

2. Independence from on-time supply issues caused by labor strikes at
Lancaster Glass and periodic flooding of the Corning Glass plant by the
nearby Chemung River. Coke bottles were always available anywhere.

3. Added employee benefits at Tek - the Coke bottles had to be emptied
by the bulb prep group before use.



The disadvantages that caused the program to be cancelled were pattern
distortions and how-the-heck do you paint the accelerator helix on the
double reentrant curve of the bottle? Also, the glass 2-liter Coke bottles
necessary to better fill the big round hole in the 545-C front panel were
not yet perfected. 2-liter plastic Coke bottles were tried but they tended
to sag into strange shapes at bake-out.



Seriously though, Tom Lee was closest.

Two Coketrons were made several years apart in the Engineering Tube Lab just
to show that it could be done. The first used a T3100 or T3160 gun and
worked surprisingly well. I can remember it displaying the crosshatch
pattern generated by the CRT engineering B2 test sets. Unfortunately, the
tube later rolled off a bench and failed the impromptu drop test. I believe
it was during a lab move.



The second tube used a T2110 gun and suffered a cracked bulb due to thermal
coefficient mismatch of the glasses during processing. This was repaired and
became the tube pictured in my book. This one did not have phosphor on the
screen but glass fluorescence would usually suffice to display a trace. Both
tubes did have complete electron guns with deflection plates. I can't recall
the second tube actually being operated but excessive gas levels due to
little or no bake-out because of the TC mismatch might have been the reason.
I remember it was mainly constructed for photos since we had none of the
first tube.



There you have the rest of the stories. Take your pick!



All of this was 30+ years ago so memories are a little fuzzy.



Peter Keller


Re: Groups.io price increase?

 

existing premium and enterprise groups will keep their legacy pricing
So it should not impact us.

David
-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Jean-Paul
Sent: 15 January 2021 12:05
To: TekScopes@groups.io
Subject: Re: [TekScopes] Groups.io price increase?

Bonjour, We can all expect the same treatment as other groups.



Dennis should calculate the yearly cost and ask for contributions by every active member.

Finally I suggest that we could migrate to a private server with our own website, setting up storage of files and a forum is not hat difficult.

Any thoughts?

Kind Regards,

Jon


Re: Groups.io price increase?

Jean-Paul
 

Dennis Good points, please can you calculate the cost/ year now or 2020 vs the new cost increase?

How many members do we have?

Jon


Re: Groups.io price increase?

toby@...
 

On 2021-01-15 7:05 a.m., Jean-Paul wrote:
Bonjour, We can all expect the same treatment as other groups.



Dennis should calculate the yearly cost and ask for contributions by every active member.

Finally I suggest that we could migrate to a private server with our own website, setting up storage of files and a forum is not hat difficult.
_Setting it up_ is not difficult.

Keeping the physical or virtual hardware paid for, running, scaled,
available, updated, and backed up is likely to cost more than
groups.io's shocking new rate -- or is a volunteer supposed to do that
for nothing?

And that's before we even talk about whether the software is going to
meet the same standard.

--T


Any thoughts?

Kind Regards,

Jon





[Resurrecting a Tek 485] Sweep not from left to right ?

marcosjl31@...
 

Hi guys !

The newbie is back !
Some news : PSU of the 485 delivers proper Low Voltage, I had to adjust the calibrator amplitude (the 5V was out of spec +/- 5mV).

I've been checking (visually) several things :
=> "Ready" indicator does not work.
=> on Chanel 1: leds (x1, x10 are not working), 1MOhm/50ohm selector has no light indication.
=> on chanel 2 : 1MOhm/50ohm selector has no light indication.
Don't know if it's complicated/hard to fix ?

Then, I was watching an interesting video on YouTube (https://www.youtube.com/watch?v=7Qg6ory3L8Y) and suddenly I realize that the sweep on the Tek 485 I've purchased seems to be inverted !

Here is what I get on Channel 2 (1MHz cal signal) : https://drive.google.com/drive/folders/1_9cXIKxCFtC60aFQ6zIm4ujq2paW4tSH

Here is the same signal picture taken from video : https://drive.google.com/drive/folders/1_9cXIKxCFtC60aFQ6zIm4ujq2paW4tSH

To check if I was right to suspect the sweep was not from left to right, I selected GND and turn TIME/DIV to 50ms : the sweep spot on the screen travels from right to left on this 485 !!

Don't think this is correct... but I may be wrong. Could this be due to improper reassembly following a repair?

Hope to here from you,
Jose


Re: WTB: SC-501 scope and other modules

Ke-Fong Lin
 

The TM5000 seties is larger, fan cooled and include HPIB control.
And that's the problem, the fan is very loud!
Unless you need to have computer controlled GPIB instrument, there's not much point.

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