Date   

Photo 5 ns/div, 1 v/div into 50 ohms. Reflections are minimal with the PTFE semi-rigid coax line. updated #photo-notice

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

The following photos have been updated in the Avalanche pulser album of the TekScopes@groups.io group.

By: Charles <charlesmorris800@...>


Re: How to explain how negative feedback lowers noise?

Tom Lee
 

Hi Ted,

I recommend continuing to read papers beyond those from 1923. It's hard to do better than to read Black's own 1934 paper (January issue of bstj, also available at archive.org, as well as worldradiohistory.com). Far from being a "canard", you will see from Black's own pen what the motivations for negative feedback were. If you still wish to refute him, you'll have to reanimate his corpse. The 1923 paper you cite enumerates many problems facing transcontinental telephony at that early time, but if you examine the list carefully, you'll see that every one of those problems is solvable, if clumsily, by open-loop means, with the conspicuous exception of distortion.

It's also important to recognize that the 1923 paper predates the advent of carrier-based telephony by several years (the author is still talking about loading coils!). Once multiple, carrier-modulated telephone signals were to share a circuit, the problem of distortion became the showstopper. Negative feedback solved that problem (and a host of others conveniently as well). Without negative feedback, AT&T could not have made transcontinental telephony practical.

-- Cheers,
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 3/27/2021 09:39, Ted Rook wrote:
While as a self-taught amateur physicist I hesitate to challenge a university professor but if
my understanding is correct (and it is often not so) the argument that the purpose of the
introduction of NFB was to reduce distortion should be viewed as a canard that belongs in
the realms of imagination where high-end audio fanatics can often be found.

Some insight into the background of problems with long distance (but not transcontinental)
telephony before the development of the negative feedback amplifier is provided in Bell
System Technical Journal 1923, January, author Clark, title "Telephone Transmission over
long cable circuits" which is to be found among other places as a free download at the
Internet Archive https://archive.org/details/bstj2-1-67

The information presented makes it clear that the idea of reduction of distortion as the driver
of development of the negative feedback amplifier fails to recognize difficulties of a more
fundamental nature that inhibited development of transcontinental telephony and demanded
a solution, which was eventually delivered by the new invention. In addition to solution of the
fundamental problem of gain instability under hostile conditions, among the other benefits
delivered by the negative feedback amplifier were improvements to frequency response,
input and output impedances and also harmonic distortion.

The article is a fascinating insight into the very early days of long distance telephony and the
content is mostly non-mathematical.

Ted Rook


On 26 Mar 2021 at 2:03, Tom Lee wrote:

The reason it didn't happen for electronics until 1927 is that the preoccupation until that point was getting more gain per tube. Positive feedback (Armstrong's regenerative amplifier) was the magic elixir that had enabled the age of electronics to begin, around WWI. Early tubes struggled to achieve voltage gains of five. The first generation of EEs was thus trained to think of getting enough gain as the main problem.

It wasn't until AT&T ran into troubles with transcontinental telephony that someone had to invent a fix for a different problem: distortion. A cascade of hundreds of repeaters demanded individual amplifiers of unprecedented linearity. This necessity was the mother of negative feedback.

Black's invention required quite a change in thinking. Now he was recommending "throwing away" precious gain in exchange for reduced distortion. This went against the training of a generation of EEs. Given that, I'm not surprised negative feedback took that long to get formalized.

Although you are absolutely right that a basic intuitive notion of negative feedback was appreciated long before electronics came along, Black was the first in history to understand explicitly that excess gain could be used as currency to pay for reductions in distortion. It is as subtle a notion as it is powerful.

The very first mathematical treatment of negative feedback was by Maxwell himself, but his analysis was limited to understanding why speed governors for steam engines could go unstable. Until technology ran into the need for exquisite precision in control, there was no need for Black to come along.

Cheers
Tom

Sent from an iThing; please excuse the terseness and typos

On Mar 25, 2021, at 23:14, "Ed Breya via groups.io" <edbreya=yahoo.com@groups.io> wrote
I don't know about this history, but am surprised that this didn't happen until 1929, well into the electronics era. Surely the concept of negative feedback in control systems has existed in nature, throughout human history, and in industry - at least since the steam era - look at the fly-ball governor, for example. Maybe in electronics, it wasn't so obvious, although it already existed in some forms, say for instance, with degenerative feedback in a vacuum tube, stabilizing the bias with the cathode resistor. People were driving horses, trains, planes, and automobiles successfully before 1929, using that PID controller in the skull.

Ed










Re: Repair of Set Screw Attachment for Tek-made VAR Pots

widgethunter <tubesnthings@...>
 

Nice! Been looking for a fix for the 1A4.Wouldn't mind getting some.Bernd Schroder

-----Original Message-----
From: Jim Adney <jadney@vwtype3.org>
To: TekScopes@groups.io
Sent: Fri, Mar 26, 2021 2:20 pm
Subject: [TekScopes] Repair of Set Screw Attachment for Tek-made VAR Pots

Quite a few years ago, I came across my first broken Tek-made VAR pot, the grey plastic ones. The plastic had broken near where the shaft enters, so that the set screw could no longer bind tightly to the shaft. As spares seemed like they might be hard to find, I came up with a more permanent solution, which you can see here:

https://groups.io/g/TekScopes/photo/262268/1 and also the following photo

These rings are tapped 4-40, the same as the OE set screws, but the ring encircles the cross-shaped portion of the pot allowing plenty of tightening of the set screw. The new, longer, set screw passes thru the original 4-40 hole, but does not use those threads, so this repair will fix a pot with stripped threads or fractured plastic there.

I made a supply of these for myself and have used a half dozen of them on various 3 series plugins. They take up almost no more room than the original pot, so I've yet to encounter a place where this wasn't a quick and neat fix. I have a small supply of these if anyone needs one, or feel free to copy the idea and make your own.


Re: How to explain how negative feedback lowers noise?

Ted Rook
 

While as a self-taught amateur physicist I hesitate to challenge a university professor but if
my understanding is correct (and it is often not so) the argument that the purpose of the
introduction of NFB was to reduce distortion should be viewed as a canard that belongs in
the realms of imagination where high-end audio fanatics can often be found.

Some insight into the background of problems with long distance (but not transcontinental)
telephony before the development of the negative feedback amplifier is provided in Bell
System Technical Journal 1923, January, author Clark, title "Telephone Transmission over
long cable circuits" which is to be found among other places as a free download at the
Internet Archive https://archive.org/details/bstj2-1-67

The information presented makes it clear that the idea of reduction of distortion as the driver
of development of the negative feedback amplifier fails to recognize difficulties of a more
fundamental nature that inhibited development of transcontinental telephony and demanded
a solution, which was eventually delivered by the new invention. In addition to solution of the
fundamental problem of gain instability under hostile conditions, among the other benefits
delivered by the negative feedback amplifier were improvements to frequency response,
input and output impedances and also harmonic distortion.

The article is a fascinating insight into the very early days of long distance telephony and the
content is mostly non-mathematical.

Ted Rook

On 26 Mar 2021 at 2:03, Tom Lee wrote:

The reason it didn't happen for electronics until 1927 is that the preoccupation until that point was getting more gain per tube. Positive feedback (Armstrong's regenerative amplifier) was the magic elixir that had enabled the age of electronics to begin, around WWI. Early tubes struggled to achieve voltage gains of five. The first generation of EEs was thus trained to think of getting enough gain as the main problem.

It wasn't until AT&T ran into troubles with transcontinental telephony that someone had to invent a fix for a different problem: distortion. A cascade of hundreds of repeaters demanded individual amplifiers of unprecedented linearity. This necessity was the mother of negative feedback.

Black's invention required quite a change in thinking. Now he was recommending "throwing away" precious gain in exchange for reduced distortion. This went against the training of a generation of EEs. Given that, I'm not surprised negative feedback took that long to get formalized.

Although you are absolutely right that a basic intuitive notion of negative feedback was appreciated long before electronics came along, Black was the first in history to understand explicitly that excess gain could be used as currency to pay for reductions in distortion. It is as subtle a notion as it is powerful.

The very first mathematical treatment of negative feedback was by Maxwell himself, but his analysis was limited to understanding why speed governors for steam engines could go unstable. Until technology ran into the need for exquisite precision in control, there was no need for Black to come along.

Cheers
Tom

Sent from an iThing; please excuse the terseness and typos

On Mar 25, 2021, at 23:14, "Ed Breya via groups.io" <edbreya=yahoo.com@groups.io> wrote
I don't know about this history, but am surprised that this didn't happen until 1929, well into the electronics era. Surely the concept of negative feedback in control systems has existed in nature, throughout human history, and in industry - at least since the steam era - look at the fly-ball governor, for example. Maybe in electronics, it wasn't so obvious, although it already existed in some forms, say for instance, with degenerative feedback in a vacuum tube, stabilizing the bias with the cathode resistor. People were driving horses, trains, planes, and automobiles successfully before 1929, using that PID controller in the skull.

Ed








Re: Persuading a 7S12 to play nice with a 7934.

Albert Otten
 

P600 connects the base of the 2N2907A either to ground or to the collectors of
the transistors which perform the (B7 XOR A16) function.
Thanks a lot Richard! It really looked as if the third pcb pin was isolated from the rest and was only there to keep the jumper save in non-gnd position. So I simply left the jumper out when trying things! This also means that interdot blanking enabled/disabled is not the correct description for the P600 positions. It's always enabled (except when left out) and enables/disables B7/A16 function you mentioned.
Now I put P600 in the non-gnd position and tried things again. And yes, now I get interdot blanking leakage in the 7A26 trace. I added a photo to your album.
As I said, my board has no P600. The collectors of the XOR transistors and the base of the 2N2907A are directly connected by a trace on the non-component side of the board.
Where is P600 located on your board? I don't see it depicted on the board illustrations of any of the manuals I have looked at.
For this I also added a photo.

Albert


Re: Persuading a 7S12 to play nice with a 7934.

Richard Steedman
 

Thanks for your insight on this Albert.

By coincidence, a paper copy of the 7S12 manual which I purchased on eBay a while back arrived today, dated June 1986. So now I have yet another reference to consult. It shows the same arrangement as the BAMA manual - P600 connects the base of the 2N2907A either to ground or to the collectors of the transistors which perform the (B7 XOR A16) function.

It's strange. With a DMM I could not find a connection of 2N2907A-base to any other component in the neighborhood or a A/B contact. But then the pair of NPN transistors with their bases to the B7 and A16 inputs would be useless. Do I overlook something?

You didn't accidentally have your P600 set such that the link between the NPNs and the 2N2907A-base was open?

As I said, my board has no P600. The collectors of the XOR transistors and the base of the 2N2907A are directly connected by a trace on the non-component side of the board. Where is P600 located on your board? I don't see it depicted on the board illustrations of any of the manuals I have looked at.

This circuit seems to have undergone many revisions over the years - perhaps reflecting issues encountered with newer generation mainframes. I share your unease about reducing the pullup resistor to 6kΩ. My other thought was to put the B7 input through an opto-isolator to get a proper 0V/5V swing and see if that cleans things up. This is easily done by lifting one end of R691 (the 430Ω resistor) off the board.

Richard


Re: 2440 and 2465B battery/ram replacement

Bob Albert
 

Chuck, where are you?  I am in Los Angeles and would like to find someone who is willing to get my Tek 2440 working.  Maybe that's not you.
The history is that when I got it, it worked but would not hold settings on power off.  I decided it must need new NVRAM modules and swapped in some I got from China on ebay.  Now the scope doesn't work at all.  I swapped one module back but still no joy.  It turns on but the display is messed up and it won't respond to any controls.
I would like to find someone who is smarter than I who is willing to correct my mistakes and get the scope operational again.  If you can assist in any way I would appreciate it.  I am willing to pay a reasonable amount, as well.
Thanks, Bob

On Friday, March 26, 2021, 07:24:54 PM PDT, Chuck Harris <cfharris@erols.com> wrote:

Hi Mark,

I am always willing to do the work.  Contact me
off group.

-Chuck Harris


On Fri, 26 Mar 2021 15:45:26 -0700 "Mark Vincent"
<orangeglowaudio@gmail.com> wrote:
Reinhard,

      I have seen this site. It is great. I do NOT have a programmer
or access to one. I do NOT have ANY TM500/5000 anything. I do not
know anyone locally that has these. This is why I asked here to see
if anyone will do the work.

Mark





Re: Repair of Set Screw Attachment for Tek-made VAR Pots

Dave Wise
 

You ought to upload the article to TekWiki at w140.com .


Dave Wise

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Wayne via groups.io <WAYNECL=AOL.COM@groups.io>
Sent: Friday, March 26, 2021 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Repair of Set Screw Attachment for Tek-made VAR Pots

Nice solution! Haven't run across a need for one yet, but if I do, the lathe is right there waiting! Thanks for the post and the nice pictures!


Re: 2440 and 2465B battery/ram replacement

Chuck Harris <cfharris@...>
 

Hi Mark,

I am always willing to do the work. Contact me
off group.

-Chuck Harris


On Fri, 26 Mar 2021 15:45:26 -0700 "Mark Vincent"
<orangeglowaudio@gmail.com> wrote:
Reinhard,

I have seen this site. It is great. I do NOT have a programmer
or access to one. I do NOT have ANY TM500/5000 anything. I do not
know anyone locally that has these. This is why I asked here to see
if anyone will do the work.

Mark





Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Dave Daniel
 

I’ll check that. It sounds like the culprit. Thanks

DaveD

On Mar 26, 2021, at 19:44, Larry McDavid <lmcdavid@lmceng.com> wrote:

Be careful to include the final hyphen character in the Google Drive link; that final character is often not in the active email link.LarrySent via the Samsung Galaxy S10
-------- Original message --------From: Dave Seiter <d.seiter@att.net> Date: 3/26/21 4:34 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful? I just tried the "drive/google" link from this email and it worked fine.-Dave On Friday, March 26, 2021, 03:14:22 PM PDT, Dave Daniel <kc0wjn@gmail.com> wrote: Can someone point me to the correct links for the documentation? Both links below are unreachable.ThanksDaveDOn 12/31/2020 2:27 PM, Jared Cabot via groups.io wrote:> Hi all,>> I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.> I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.> Here's a link to the youtube video:> https://www.youtube.com/watch?v=Afwqtc6Fxd4>> And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.> https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4->> Direct link to the new manual:> https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing>> Let me know what you think, and let me know if you see any errors that need correcting. :)>> Regards> Jared.>>> >>>-- This email has been checked for viruses by Avast antivirus software.https://www.avast.com/antivirus




Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Larry McDavid
 

Be careful to include the final hyphen character in the Google Drive link; that final character is often not in the active email link.LarrySent via the Samsung Galaxy S10

-------- Original message --------From: Dave Seiter <d.seiter@att.net> Date: 3/26/21 4:34 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful? I just tried the "drive/google" link from this email and it worked fine.-Dave    On Friday, March 26, 2021, 03:14:22 PM PDT, Dave Daniel <kc0wjn@gmail.com> wrote:  Can someone point me to the correct links for the documentation? Both links below are unreachable.ThanksDaveDOn 12/31/2020 2:27 PM, Jared Cabot via groups.io wrote:> Hi all,>> I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.> I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.> Here's a link to the youtube video:> https://www.youtube.com/watch?v=Afwqtc6Fxd4>> And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.> https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4->> Direct link to the new manual:> https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing>> Let me know what you think, and let me know if you see any errors that need correcting. :)>> Regards> Jared.>>> >>>-- This email has been checked for viruses by Avast antivirus software.https://www.avast.com/antivirus


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Dave Daniel
 

Thanks.

On Mar 26, 2021, at 19:33, Dave Seiter <d.seiter@att.net> wrote:

I just tried the "drive/google" link from this email and it worked fine.
-Dave
On Friday, March 26, 2021, 03:14:22 PM PDT, Dave Daniel <kc0wjn@gmail.com> wrote:

Can someone point me to the correct links for the documentation? Both
links below are unreachable.

Thanks

DaveD


On 12/31/2020 2:27 PM, Jared Cabot via groups.io wrote:
Hi all,

I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.
I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.
Here's a link to the youtube video:
https://www.youtube.com/watch?v=Afwqtc6Fxd4

And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.
https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4-

Direct link to the new manual:
https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing

Let me know what you think, and let me know if you see any errors that need correcting. :)

Regards
Jared.






--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus












Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Dave Seiter
 

I just tried the "drive/google" link from this email and it worked fine.
-Dave

On Friday, March 26, 2021, 03:14:22 PM PDT, Dave Daniel <kc0wjn@gmail.com> wrote:

Can someone point me to the correct links for the documentation? Both
links below are unreachable.

Thanks

DaveD


On 12/31/2020 2:27 PM, Jared Cabot via groups.io wrote:
Hi all,

I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.
I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.
Here's a link to the youtube video:
https://www.youtube.com/watch?v=Afwqtc6Fxd4

And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.
https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4-

Direct link to the new manual:
https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing

Let me know what you think, and let me know if you see any errors that need correcting. :)

Regards
Jared.






--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Re: 2440 and 2465B battery/ram replacement

Mark Vincent
 

Reinhard,

I have seen this site. It is great. I do NOT have a programmer or access to one. I do NOT have ANY TM500/5000 anything. I do not know anyone locally that has these. This is why I asked here to see if anyone will do the work.

Mark


Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?

Dave Daniel
 

Can someone point me to the correct links for the documentation? Both links below are unreachable.

Thanks

DaveD

On 12/31/2020 2:27 PM, Jared Cabot via groups.io wrote:
Hi all,

I have been accumulating TM500 modules and mainframes for a little while, so I recently finished building an 067-1201-99 TM500 mainframe tester from the Tek construction notes floating around.
I updated the design somewhat and designed it for simplified construction (Not a single wire to strip and solder!) and I thought someone here might be interested in taking a look or even building one themselves.
Here's a link to the youtube video:
https://www.youtube.com/watch?v=Afwqtc6Fxd4

And here's a link to the google drive with all the gerbers and schematics and stuff. I went so far as to rewrite the manual with the alterations and corrections included.
https://drive.google.com/drive/folders/1yj52Z_BtGZ7Q9BB2jS9Lf2Uz39turS4-

Direct link to the new manual:
https://drive.google.com/file/d/1iqpcqheb01qMioQwcUhyWv6A37v2HPro/view?usp=sharing

Let me know what you think, and let me know if you see any errors that need correcting. :)

Regards
Jared.




--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Re: Repair of Set Screw Attachment for Tek-made VAR Pots

Paul Amaranth
 

Quite an elegant solution!

Paul

On Fri, Mar 26, 2021 at 02:20:11PM -0700, Jim Adney wrote:
Quite a few years ago, I came across my first broken Tek-made VAR pot, the grey plastic ones. The plastic had broken near where the shaft enters, so that the set screw could no longer bind tightly to the shaft. As spares seemed like they might be hard to find, I came up with a more permanent solution, which you can see here:

https://groups.io/g/TekScopes/photo/262268/1 and also the following photo

These rings are tapped 4-40, the same as the OE set screws, but the ring encircles the cross-shaped portion of the pot allowing plenty of tightening of the set screw. The new, longer, set screw passes thru the original 4-40 hole, but does not use those threads, so this repair will fix a pot with stripped threads or fractured plastic there.

I made a supply of these for myself and have used a half dozen of them on various 3 series plugins. They take up almost no more room than the original pot, so I've yet to encounter a place where this wasn't a quick and neat fix. I have a small supply of these if anyone needs one, or feel free to copy the idea and make your own.
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: Repair of Set Screw Attachment for Tek-made VAR Pots

Wayne
 

Nice solution! Haven't run across a need for one yet, but if I do, the lathe is right there waiting! Thanks for the post and the nice pictures!


Repair of Set Screw Attachment for Tek-made VAR Pots

Jim Adney
 

Quite a few years ago, I came across my first broken Tek-made VAR pot, the grey plastic ones. The plastic had broken near where the shaft enters, so that the set screw could no longer bind tightly to the shaft. As spares seemed like they might be hard to find, I came up with a more permanent solution, which you can see here:

https://groups.io/g/TekScopes/photo/262268/1 and also the following photo

These rings are tapped 4-40, the same as the OE set screws, but the ring encircles the cross-shaped portion of the pot allowing plenty of tightening of the set screw. The new, longer, set screw passes thru the original 4-40 hole, but does not use those threads, so this repair will fix a pot with stripped threads or fractured plastic there.

I made a supply of these for myself and have used a half dozen of them on various 3 series plugins. They take up almost no more room than the original pot, so I've yet to encounter a place where this wasn't a quick and neat fix. I have a small supply of these if anyone needs one, or feel free to copy the idea and make your own.


Re: Recapping Tektronix 2465

Chuck Harris <cfharris@...>
 

Why attribute that to me?

I didn't write the statement you quote as being mine,
but I can see where it would make sense.

Try it this way:

Pink paint can be used to repaint a red fire truck,
but pink paint is not recommended to repaint a red fire truck.

-Chuck Harris


On Fri, 26 Mar 2021 12:40:58 -0700 "Jim Adney" <jadney@vwtype3.org>
wrote:
On Fri, Mar 26, 2021 at 01:46 PM, Chuck Harris wrote:

A 2 type can replace a 1 type. A 2 type is
not recommended to replace a 1 type.
Pretty sure there's a typo in here somewhere.... ;-)





Re: Recapping Tektronix 2465

Jim Adney
 

On Fri, Mar 26, 2021 at 01:46 PM, Chuck Harris wrote:

A 2 type can replace a 1 type. A 2 type is
not recommended to replace a 1 type.
Pretty sure there's a typo in here somewhere.... ;-)

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