Date   
TM500/TM5000 extender v0.8

Ke-Fong Lin
 

Hi everyone,

So I've soldered the TM500/TM5000 extender and was able to successfully test it.
It works! Both as simple extender and as a debugging device.
See photos: https://groups.io/g/TekScopes/album?id=243643

However, it has one routing error, I forgot the collector of the PNP pass transistor.
And somehow, I was distracted enough to not see it throught design rule check in kicad.
In fact, visual inspection should have spot it. This is easily fixed by a bodge wire.
Also the footprint for "power ready" circuitry's transistor has pads that are too close.
That needs to be changed.

Otherwise, as you can see in the photo, I was able to power an AA501 without a mainframe.
It uses only (+/-26VDC and +8VDC). For the pass transistors, I've used TIP35C (NPN) and TIP36C (PNP).
These are reportedly the ones used in later TM5006A rack, high power compartment.
Surprisingly, the modules are quite power "hungry", FG501 requires 200mA for each -/+ 26VDC supplies.
Whereas, the AA501 use 300mA for +/- 26VDC and 200mA for +8VDC.

I have to test with a TM5000 series rack and module, but I don't expect problem.

A few remarks, I used individual wires, but now think ribbon cable would be better.
The idea was that not all pads need to be soldered, for example VDC supplies are on pads on both side.
So sometimes a single appropriate diameter wire (I've used 22AWG which is overkill) would be enough.
This ended up being very tedious and time consuming at soldering.
In particular, I've left the "optional" function specific pads unconnected.

Regarding debugging use, it still ends up with a bunch of messy wires, and the PCB pads are exposed.
That's definitely not professional but ok for hobby use.

I've already fixed the PCB in kicad so I can spin version 1.0 soon.

In the meantime, I've 3 PCBs left. So if one of you wanna try, I can send for the cost of shipping.
You will have to add the bodge wire (see photo) of course.

Best regards,

Re: Any Tektronix magnetic shield for a CRT? A strange problem...

 

Hi Dennis,

The 154-0667-00 CRT in the 1502 TDR which you suggested is indeed a nice tube, quite interesting. Thank you for the suggestion.
Something unusual I find for a Tektronix CRT is that its cathode is a direct heated filament. And the blanking of the trace is not done through the grid or cathode but by a pair of dedicated electrodes that I guess deflect the beam out of the area of the screen. It does not have post-acceleration, and the HV supply in the 1502 has a rare simplicity. I like it for the square screen and the internal graticule. But in the scope I have the square mumetal shield would run out of space, plus to interface it would require multiple modifications. So for the time being I may stay with what I have, and leave for later my dream of building a scope around the tube the 547 has, This when the time of the day increases from 24 to 48 hours (yes, retired people also run out of time)

The video form the company Mumetal you quoted is very interesting. Could sleeping inside a mumetal shield that eliminates the earth's magnetic field have homeopathic benefits?

Ernesto

Re: Any Tektronix magnetic shield for a CRT? A strange problem...

Leon Robinson
 

If I remember right some of the Heathkit scopes in the 60s or 70s had rectangular CRTs.

Leon Robinson    K5JLR

Political Correctness is a Political Disease.

Politicians and Diapers should be changed
often and for the same reasons.

On Thursday, March 26, 2020, 10:27:27 PM CDT, Ed Breya via Groups.Io <edbreya=yahoo.com@groups.io> wrote:

Before going through all sorts of grief with mu metal, you may want to take it all apart and carefully inspect the CRT and shield - you may find an actual magnet stuck inside somewhere. This happened to me once, working on an old scope long ago. I found a small permanent magnet that must have gotten dropped inside the scope guts, and it found its way to the nice mu shield right at the back edge by the CRT gun. At first I thought it was a mounting screw head, then realized it was a magnet hanging there.

If you look at "real" mu shields for CRTs and other devices, you'll find they are typically fully closed, magnetically, where the joints are overlapped quite a bit, or riveted, crimped, or spot welded. If your home-made one is just rolled but without the edges tightly bonded, there's a natural air gap that concentrates flux. Also, it may not even be mu metal, but just mild steel. Mu will tend to look like stainless steel, and be very soft, and rust-free. It is easily solderable. It should not retain magnetization very well, which is why it's good for shielding. The shielding effectiveness does degrade from deformation, but doesn't go to zero. I wouldn't worry too much about minor dents and dings.

If you suspect some high degree of localized magnetization "hot spots," just sprinkle some fine iron filings or magnetic laser toner around on it, and look for the patterns.

Ed

Re: need a tunnel diode

Mlynch001
 

Aldue,

How many do you need? I’ve got a spare from a 465. Same part.

--
Michael Lynch
Dardanelle, AR

Re: need a tunnel diode

ROLYNN PRECHTL K7DFW
 

Russia is making most of the TDs these days. There are usually plenty of Russian TDs on eBay.

========================================================


Get the real thing. Search eBay for "152-0125-01"


Rolynn
Tek Bvtn & Sunset 1966-1971

Re: need a tunnel diode

 

Hi Aldue,
Russia is making most of the TDs these days. There are usually plenty of Russian TDs on eBay. They have quite a selection of currents, peak voltages, and capacitances. I know many of our members have asked about them before buying the ones on eBay so do a search of our archives and you will find a lot of information on what's available from Russia.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of aldue
Sent: Thursday, March 26, 2020 7:44 PM
To: TekScopes@groups.io
Subject: [TekScopes] need a tunnel diode

Hi Tek fans. Me too. I am semi-bleeding for a tunnel diode. Please suggest substitutes or sources. Tek 152-0125-00, 4.7mA 15-18pF THANK you, aldue





--
Dennis Tillman W7PF
TekScopes Moderator

Re: Any Tektronix magnetic shield for a CRT? A strange problem...

Ed Breya
 

Before going through all sorts of grief with mu metal, you may want to take it all apart and carefully inspect the CRT and shield - you may find an actual magnet stuck inside somewhere. This happened to me once, working on an old scope long ago. I found a small permanent magnet that must have gotten dropped inside the scope guts, and it found its way to the nice mu shield right at the back edge by the CRT gun. At first I thought it was a mounting screw head, then realized it was a magnet hanging there.

If you look at "real" mu shields for CRTs and other devices, you'll find they are typically fully closed, magnetically, where the joints are overlapped quite a bit, or riveted, crimped, or spot welded. If your home-made one is just rolled but without the edges tightly bonded, there's a natural air gap that concentrates flux. Also, it may not even be mu metal, but just mild steel. Mu will tend to look like stainless steel, and be very soft, and rust-free. It is easily solderable. It should not retain magnetization very well, which is why it's good for shielding. The shielding effectiveness does degrade from deformation, but doesn't go to zero. I wouldn't worry too much about minor dents and dings.

If you suspect some high degree of localized magnetization "hot spots," just sprinkle some fine iron filings or magnetic laser toner around on it, and look for the patterns.

Ed

Re: Any Tektronix magnetic shield for a CRT? A strange problem...

 

Hi Bruce,

Thank you for the tip. I will keep this annealing in a slowly extinguishing bed of coals in mind.

Ernesto

Re: Tek 222/224 Battery Replacement

Byron Hayes, Jr.
 

Jeff,

I have three of these scopes, and would be interested in three boards.

Byron, WA6ATN

Byron Hayes, Jr.
4256 Navajo Ave.
Toluca Lake, CA 91602-2914
(818) 752-4653

At 05:57 PM 3/26/2020, Jeff Davis wrote:
Hi Gary,

What I'm planning to do for the battery charger is have the boards fabricated and stuffed offshore. I'm awaiting a final quote from them - they need to source a couple of parts. So the "kit" I would propose to provide would be an assembled and tested PCB, a 3D printed case that fits into the battery cavity of the Tek 222/224 (without modifying the scope other than removing the SLA battery), and possibly a few miscellaneous pieces such as light pipes to bring the LED status lights to the front of the case and a jumper cable to go from the board to the connector on the scope. (Speaking of which - would you happen to know a source for the female connector that goes on the end of the cable the plugs into the male connector on the scope?). Buyers would have to provide their own 18650 Lithium batteries - but they could be the cheaper unprotected version since there's overcharge protection built onto the board.

I've attached a couple of pictures of the case installed into a 222A.

I'm thinking for TekScopes members who order in the initial batch a price of my cost plus shipping plus $10. The $10 is to take my wife out to dinner so she'll continue to support me doing these crazy projects! After the first batch I'll see what the market will bear in terms of price. Right now in quantities of 10, my cost would be about $60 each.

Regards,
Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of g m <saphill7@...>
Sent: Thursday, March 26, 2020 11:37 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Tek 222/224 Battery Replacement

I'd be interested also, regards, Gary


On Thu, Mar 26, 2020 at 2:14 PM Dave Voorhis <voorhis@...> wrote:

On 26 Mar 2020, at 17:02, Jeff Davis <n0dyjeff@...> wrote:


Hi all,

One of my customers approached me a few weeks ago about a project to
replace the sealed lead acid battery (now unobtainium) in Tek 222/224
scopes with lithium ion cells that presumably will continue to be available
for the foreseeable future. He pointed me to a really well done project
with a public domain license. There's a YouTube video on it -
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FLJ2VS3aohV0&amp;data=02%7C01%7C%7C009602ec1fbc4ca1fff708d7d1c58fa1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637208518750518674&amp;sdata=3LLpfBLKpD4ou3O%2F21bIM26qi5S3VSq%2B4aM68HOss9E%3D&amp;reserved=0.

After a couple of weeks of capturing schematics, sourcing parts, etc.
I'm about ready to hit Send on an order for the PCBs. Before I do that,
however, I wanted to check with the community to see if there's sufficient
interest to order more than the minimum quantity of boards.

How about it, Tek 222/224 collectors? Any interest in a battery pack
replacement based on the design in the YouTube video above?

Regards,
Jeff / N0DY
Definitely interested. I bought a 222 to add to my collection, but its
turned out to be surprisingly useful. Id like to replace the dud lead-acid
battery but the usual replacements involve cutting the case, which Im
reluctant to do. I think the YouTube video approach doesnt cut the case?

I didnt watch the whole thing, admittedly.

Either way, Im definitely interested in a board. Im in the UK, so I
dont know if shipping might be an issue though I guess a board should fit
in an envelope.






Re: Any Tektronix magnetic shield for a CRT? A strange problem...

greenboxmaven
 

Using a degausser would work, but if the shield is permalloy or mu metal, the work hardening of the damaged area will re-magnetize if exposed to a field. The design of the mu metal or permalloy is to achieve a metal crystalline structure that will pass magnetic fields around the CRT without becoming magnetized by them. No degaussing would be needed. The color TV shield and shadow mask will re-magnetize if the set is rotated about it's vertical axis. With early receivers that did not have built in degaussers, we had to carefully instruct customers that it was acceptable to move the set directly forward away from the wall to clean behind it and push it back so long as it was not rotated.

Bruce Gentry, KA2IVY

On 3/26/20 10:11 PM, petertech99h via Groups.Io wrote:
Hi all!
Heating the shield til you demagnetize it would work, but what about using a AC degausser instead? Turn it on 2 feet away and then bring it close and move it all over the shield, when you've covered every area, then start to back off the degausser to about 2 feet before turning it off.

I remember this worked well on color TV CRTs where kids had dragged magnets all over the screen! (The mask inside the CRT would distort colors if magnetized.)

See ya!
Pete

On Thursday, March 26, 2020, 8:55:41 p.m. EDT, greenboxmaven via Groups.Io <ka2ivy=verizon.net@groups.io> wrote:
I based it on a process we used to repair cast iron gears. The goal was
different, but the process worked fine. Neighboring shops wondered what
we were cooking on the grill in the middle of winter, until they saw one
of us in full welding emsemble raise the lid. The elevator craft
required a very diverse variety of skills, especially the companies that
did actual REPAIRS.

Bruce Gentry, KA2IVY Elevator Constructors Local 62, retired


On 3/26/20 7:42 PM, Dennis Tillman W7PF wrote:
Hi Bruce,
That was a very clever way to fix the mu-metal.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of greenboxmaven via Groups.Io
Sent: Thursday, March 26, 2020 3:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange problem...

Common magnetic shield materials are permalloy and mu metal. Soft iron is also usable, but not as good. All of them have their shielding properties impaired by mechanical stress, such as being dented, after they have been fabricated and annealed. Scope tube shields were fabricated and then heated to red heat, often in a hydrogen atmosphere, and then allowed to cool slowly. I have a Heathkit monitor scope with a shield that had been deeply dented, breaking the CRT inside. Once I straightened it out, it was magnetized and distorted the trace. I laid it on well lit charcoal, then closed the top of the grill and let the fire burn out. Next day, I brushed it off, painted it, and re-installed it. The magnetism was gone.

Bruce Gentry, KA2IVY


On 3/26/20 5:35 PM, Ernesto wrote:
Has anyone a recommendation for a mumetal Tektronix shield that could fit an old CRT of 4 inch face plate, 2 inch neck and 13 inch length?


This is why I am looking for a CRT shield, if possible a Tektronix one, that has not been banged around. If it is not available, I might try to build one with some permalloy sheet, or forget about it and play with something else.

Thank you for your help, and hopefully you never experience such CRT
beam problems (no attaching of big speakers to the side of your
oscilloscope)

Ernesto









need a tunnel diode

aldue
 

Hi Tek fans. Me too. I am semi-bleeding for a tunnel diode. Please suggest substitutes or sources. Tek 152-0125-00, 4.7mA 15-18pF THANK you, aldue

fuzzy fat weak trace 464 CURED

aldue
 

The interface board had failed resistors which killed 2 transistors. Test Point 1443 read 22 Volts. It is supposed to be 27 Volts. Q1432, Q1436, R1437 and R1443. Noise kept the trace fat until the case was reinstalled. Now I need a tunnel diode for a different problem.

Re: 184 Time mark Gen. Needs filter caps

david
 

Picture 0f 50mS marks is in picture folder "184 Time mark Gen. Needs filter Caps" , can't get oscillator to adjust to 10Mhz, max is 9.999843. I know this is close enough but I am retired and have plenty of time to tinker with it. I Need to lower the capacitance range of C11. I am going to try adding maybe a 4.7pF cap in series with C11 to bring the frequency adjustment range higher, (make capacitance lower). I am checking frequency against a GPSDO at 10Mhz, so I know I'm close.

Re: Any Tektronix magnetic shield for a CRT? A strange problem...

petertech99h
 

Hi all!
Heating the shield til you demagnetize it would work, but what about using a AC degausser instead?  Turn it on 2 feet away and then bring it close and move it all over the shield, when you've covered every area, then start to back off the degausser to about 2 feet before turning it off. 

I remember this worked well on color TV CRTs where kids had dragged magnets all over the screen! (The mask inside the CRT would distort colors if magnetized.)

See ya!
Pete

On Thursday, March 26, 2020, 8:55:41 p.m. EDT, greenboxmaven via Groups.Io <ka2ivy=verizon.net@groups.io> wrote:

I based it on a process we used to repair cast iron gears. The goal was
different, but the process worked fine.  Neighboring shops wondered what
we were cooking on the grill in the middle of winter, until they saw one
of us in full welding emsemble raise the lid. The elevator craft
required a very diverse variety of skills, especially the companies that
did actual REPAIRS.

      Bruce Gentry, KA2IVY Elevator Constructors Local 62, retired


On 3/26/20 7:42 PM, Dennis Tillman W7PF wrote:
Hi Bruce,
That was a very clever way to fix the mu-metal.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of greenboxmaven via Groups.Io
Sent: Thursday, March 26, 2020 3:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange problem...

Common magnetic shield materials are permalloy and mu metal. Soft iron is also usable, but not as good.  All of them have their shielding properties impaired by mechanical stress, such as being dented, after they have been fabricated and annealed. Scope tube shields were fabricated and then heated to red heat, often in a hydrogen atmosphere, and then allowed to cool slowly. I have a Heathkit monitor scope with a shield that had been deeply dented, breaking the CRT inside. Once I straightened it out, it was magnetized and distorted the trace. I laid it on well lit charcoal, then closed the top of the grill and let the fire burn out. Next day, I brushed it off, painted it, and re-installed it. The magnetism was gone.

      Bruce Gentry, KA2IVY


On 3/26/20 5:35 PM, Ernesto wrote:
Has anyone a recommendation for a mumetal Tektronix shield that could fit an old CRT of 4 inch face plate, 2 inch neck and 13 inch length?


This is why I am looking for a CRT shield, if possible a Tektronix one, that has not been banged around. If it is not available, I might try to build one with some permalloy sheet, or forget about it and play with something else.

Thank you for your help, and hopefully you never experience such CRT
beam problems  (no attaching of big speakers to the side of your
oscilloscope)

Ernesto






Re: Tek 222/224 Battery Replacement

Jeff Davis
 

I should mention, in all fairness, that the case design was done by NearFarMedia and posted to Thingiverse. https://www.thingiverse.com/thing:3623622

Thanks, dude!

Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jeff Davis <n0dyjeff@...>
Sent: Thursday, March 26, 2020 5:57 PM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Tek 222/224 Battery Replacement

Hi Gary,

What I'm planning to do for the battery charger is have the boards fabricated and stuffed offshore. I'm awaiting a final quote from them - they need to source a couple of parts. So the "kit" I would propose to provide would be an assembled and tested PCB, a 3D printed case that fits into the battery cavity of the Tek 222/224 (without modifying the scope other than removing the SLA battery), and possibly a few miscellaneous pieces such as light pipes to bring the LED status lights to the front of the case and a jumper cable to go from the board to the connector on the scope. (Speaking of which - would you happen to know a source for the female connector that goes on the end of the cable the plugs into the male connector on the scope?). Buyers would have to provide their own 18650 Lithium batteries - but they could be the cheaper unprotected version since there's overcharge protection built onto the board.

I've attached a couple of pictures of the case installed into a 222A.

I'm thinking for TekScopes members who order in the initial batch a price of my cost plus shipping plus $10. The $10 is to take my wife out to dinner so she'll continue to support me doing these crazy projects! After the first batch I'll see what the market will bear in terms of price. Right now in quantities of 10, my cost would be about $60 each.

Regards,
Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of g m <saphill7@...>
Sent: Thursday, March 26, 2020 11:37 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Tek 222/224 Battery Replacement

I'd be interested also, regards, Gary


On Thu, Mar 26, 2020 at 2:14 PM Dave Voorhis <voorhis@...> wrote:

On 26 Mar 2020, at 17:02, Jeff Davis <n0dyjeff@...> wrote:


Hi all,

One of my customers approached me a few weeks ago about a project to
replace the sealed lead acid battery (now unobtainium) in Tek 222/224
scopes with lithium ion cells that presumably will continue to be available
for the foreseeable future. He pointed me to a really well done project
with a public domain license. There's a YouTube video on it -
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FLJ2VS3aohV0&amp;data=02%7C01%7C%7Cb2f394551aab42d9728e08d7d1e9d738%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637208674568286747&amp;sdata=ElebQlpKlSVddQb46OosmekQvi9ZsfT8THcUMytXx2s%3D&amp;reserved=0.

After a couple of weeks of capturing schematics, sourcing parts, etc.
I'm about ready to hit Send on an order for the PCBs. Before I do that,
however, I wanted to check with the community to see if there's sufficient
interest to order more than the minimum quantity of boards.

How about it, Tek 222/224 collectors? Any interest in a battery pack
replacement based on the design in the YouTube video above?

Regards,
Jeff / N0DY
Definitely interested. I bought a 222 to add to my collection, but it’s
turned out to be surprisingly useful. I’d like to replace the dud lead-acid
battery but the usual replacements involve cutting the case, which I’m
reluctant to do. I think the YouTube video approach doesn’t cut the case?

I didn’t watch the whole thing, admittedly.

Either way, I’m definitely interested in a board. I’m in the UK, so I
don’t know if shipping might be an issue though I guess a board should fit
in an envelope.



Re: Tek 222/224 Battery Replacement

Jeff Davis
 

Hi Miguel,

You have an excellent point. Of course, the goal of this project was to leave the scope as absolutely stock as possible, replacing only the SLA battery with the battery / charger assembly. Modifying the 222 itself wouldn't be in sync with that goal, but I could see how it could be an attractive option for someone.

Regards,
Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Miguel Work <harrimansat@...>
Sent: Thursday, March 26, 2020 12:10 PM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Tek 222/224 Battery Replacement

Well done!

But if you know how to make a lithium charger, your will know how to modify the 222 to work directly with lithium batteries :)

Regards!


-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Dave Voorhis
Enviado el: jueves, 26 de marzo de 2020 19:14
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Tek 222/224 Battery Replacement

On 26 Mar 2020, at 17:02, Jeff Davis <n0dyjeff@...> wrote:


Hi all,

One of my customers approached me a few weeks ago about a project to replace the sealed lead acid battery (now unobtainium) in Tek 222/224 scopes with lithium ion cells that presumably will continue to be available for the foreseeable future. He pointed me to a really well done project with a public domain license. There's a YouTube video on it - https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FLJ2VS3aohV0&amp;data=02%7C01%7C%7C9a5962021c7a4cc0a1c308d7d1b95aa7%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637208466326005372&amp;sdata=zEzghd6Ds7db1qBGGbbp2104tVjZQ3N9fjy6eEZhEWg%3D&amp;reserved=0.

After a couple of weeks of capturing schematics, sourcing parts, etc. I'm about ready to hit Send on an order for the PCBs. Before I do that, however, I wanted to check with the community to see if there's sufficient interest to order more than the minimum quantity of boards.

How about it, Tek 222/224 collectors? Any interest in a battery pack replacement based on the design in the YouTube video above?

Regards,
Jeff / N0DY
Definitely interested. I bought a 222 to add to my collection, but it’s turned out to be surprisingly useful. I’d like to replace the dud lead-acid battery but the usual replacements involve cutting the case, which I’m reluctant to do. I think the YouTube video approach doesn’t cut the case?

I didn’t watch the whole thing, admittedly.

Either way, I’m definitely interested in a board. I’m in the UK, so I don’t know if shipping might be an issue though I guess a board should fit in an envelope.

Re: Tek 222/224 Battery Replacement

Jeff Davis
 

Hi Gary,

What I'm planning to do for the battery charger is have the boards fabricated and stuffed offshore. I'm awaiting a final quote from them - they need to source a couple of parts. So the "kit" I would propose to provide would be an assembled and tested PCB, a 3D printed case that fits into the battery cavity of the Tek 222/224 (without modifying the scope other than removing the SLA battery), and possibly a few miscellaneous pieces such as light pipes to bring the LED status lights to the front of the case and a jumper cable to go from the board to the connector on the scope. (Speaking of which - would you happen to know a source for the female connector that goes on the end of the cable the plugs into the male connector on the scope?). Buyers would have to provide their own 18650 Lithium batteries - but they could be the cheaper unprotected version since there's overcharge protection built onto the board.

I've attached a couple of pictures of the case installed into a 222A.

I'm thinking for TekScopes members who order in the initial batch a price of my cost plus shipping plus $10. The $10 is to take my wife out to dinner so she'll continue to support me doing these crazy projects! After the first batch I'll see what the market will bear in terms of price. Right now in quantities of 10, my cost would be about $60 each.

Regards,
Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of g m <saphill7@...>
Sent: Thursday, March 26, 2020 11:37 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Tek 222/224 Battery Replacement

I'd be interested also, regards, Gary


On Thu, Mar 26, 2020 at 2:14 PM Dave Voorhis <voorhis@...> wrote:

On 26 Mar 2020, at 17:02, Jeff Davis <n0dyjeff@...> wrote:


Hi all,

One of my customers approached me a few weeks ago about a project to
replace the sealed lead acid battery (now unobtainium) in Tek 222/224
scopes with lithium ion cells that presumably will continue to be available
for the foreseeable future. He pointed me to a really well done project
with a public domain license. There's a YouTube video on it -
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FLJ2VS3aohV0&amp;data=02%7C01%7C%7C009602ec1fbc4ca1fff708d7d1c58fa1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637208518750518674&amp;sdata=3LLpfBLKpD4ou3O%2F21bIM26qi5S3VSq%2B4aM68HOss9E%3D&amp;reserved=0.

After a couple of weeks of capturing schematics, sourcing parts, etc.
I'm about ready to hit Send on an order for the PCBs. Before I do that,
however, I wanted to check with the community to see if there's sufficient
interest to order more than the minimum quantity of boards.

How about it, Tek 222/224 collectors? Any interest in a battery pack
replacement based on the design in the YouTube video above?

Regards,
Jeff / N0DY
Definitely interested. I bought a 222 to add to my collection, but it’s
turned out to be surprisingly useful. I’d like to replace the dud lead-acid
battery but the usual replacements involve cutting the case, which I’m
reluctant to do. I think the YouTube video approach doesn’t cut the case?

I didn’t watch the whole thing, admittedly.

Either way, I’m definitely interested in a board. I’m in the UK, so I
don’t know if shipping might be an issue though I guess a board should fit
in an envelope.



Re: Any Tektronix magnetic shield for a CRT? A strange problem...

greenboxmaven
 

I based it on a process we used to repair cast iron gears. The goal was different, but the process worked fine. Neighboring shops wondered what we were cooking on the grill in the middle of winter, until they saw one of us in full welding emsemble raise the lid. The elevator craft required a very diverse variety of skills, especially the companies that did actual REPAIRS.

Bruce Gentry, KA2IVY Elevator Constructors Local 62, retired

On 3/26/20 7:42 PM, Dennis Tillman W7PF wrote:
Hi Bruce,
That was a very clever way to fix the mu-metal.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of greenboxmaven via Groups.Io
Sent: Thursday, March 26, 2020 3:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange problem...

Common magnetic shield materials are permalloy and mu metal. Soft iron is also usable, but not as good. All of them have their shielding properties impaired by mechanical stress, such as being dented, after they have been fabricated and annealed. Scope tube shields were fabricated and then heated to red heat, often in a hydrogen atmosphere, and then allowed to cool slowly. I have a Heathkit monitor scope with a shield that had been deeply dented, breaking the CRT inside. Once I straightened it out, it was magnetized and distorted the trace. I laid it on well lit charcoal, then closed the top of the grill and let the fire burn out. Next day, I brushed it off, painted it, and re-installed it. The magnetism was gone.

Bruce Gentry, KA2IVY


On 3/26/20 5:35 PM, Ernesto wrote:
Has anyone a recommendation for a mumetal Tektronix shield that could fit an old CRT of 4 inch face plate, 2 inch neck and 13 inch length?


This is why I am looking for a CRT shield, if possible a Tektronix one, that has not been banged around. If it is not available, I might try to build one with some permalloy sheet, or forget about it and play with something else.

Thank you for your help, and hopefully you never experience such CRT
beam problems (no attaching of big speakers to the side of your
oscilloscope)

Ernesto






Re: Any Tektronix magnetic shield for a CRT? A strange problem...

 

Hi Bruce,
That was a very clever way to fix the mu-metal.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of greenboxmaven via Groups.Io
Sent: Thursday, March 26, 2020 3:38 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange problem...

Common magnetic shield materials are permalloy and mu metal. Soft iron is also usable, but not as good. All of them have their shielding properties impaired by mechanical stress, such as being dented, after they have been fabricated and annealed. Scope tube shields were fabricated and then heated to red heat, often in a hydrogen atmosphere, and then allowed to cool slowly. I have a Heathkit monitor scope with a shield that had been deeply dented, breaking the CRT inside. Once I straightened it out, it was magnetized and distorted the trace. I laid it on well lit charcoal, then closed the top of the grill and let the fire burn out. Next day, I brushed it off, painted it, and re-installed it. The magnetism was gone.

Bruce Gentry, KA2IVY


On 3/26/20 5:35 PM, Ernesto wrote:
Has anyone a recommendation for a mumetal Tektronix shield that could fit an old CRT of 4 inch face plate, 2 inch neck and 13 inch length?


This is why I am looking for a CRT shield, if possible a Tektronix one, that has not been banged around. If it is not available, I might try to build one with some permalloy sheet, or forget about it and play with something else.

Thank you for your help, and hopefully you never experience such CRT
beam problems (no attaching of big speakers to the side of your
oscilloscope)

Ernesto








--
Dennis Tillman W7PF
TekScopes Moderator

Re: Any Tektronix magnetic shield for a CRT? A strange problem...

 

Hi Ernesto,
I would think it will be nearly impossible to find a mu-metal shield that is the right size for a cheap CRT you bought 50 years ago.
Instead why not try thinking outside the box or at least approach the problem in reverse.
For instance look for a CRT that has a mu-metal shield already attached to it that will fit into the space you have. The 154-0667-00/-01/-02 CRT used in the 1502 TDR is quite nice. It is rectangular 3"x 2 1/2" and it has an 8 x 10 internal graticule. It is 10" long so it will fit in your scope. You also get an interesting challenge which is to see how much you have learned since you figured out a clever way to shield the scope you repaired 50 years ago. You should be capable of figuring how to install a much more modern tube now.

I once asked the TekScopes members if they had any suggestions for experiments I could do with mu-metal since I saved some of the shields from older Tek Scopes and I didn't want to throw it out if there was a use for it. I even went onto the web pages of companies that made mu-metal to see if they had any clever things that could only be done with it.
The subject of my post was Fun with Mu-Metal (Message #37701 · 04/12/09). There were 2 interesting replies and 8 that were not so interesting. The best one was "Use it to make one of those caps that those worried about alien mind control wear."
I already did that long ago. I never leave home without my mu-metal hat and my copper bracelets. Unfortunately the hat didn't help with the other voices in my head - could they be electrostatic voices? Maybe I could stop them if I put the hat in one of those pink electrostatic bags when I'm not using it.

This company has a little video showing how they shape and machine mu-metal.
http://www.mumetal.com
They list a few examples of what mu-metal is being used for today. Aside from the MRI machines I don't think the other two applications they mention use much if it:
* When the Smithsonian Astrophysical Observatory scientists set up an experiment to test Einstein's Theory of Relativity, they specified MuShield to protect the atomic clock used to explore the structure of space and time.
* High Technology companies using SQUID (Superconducting Quantum Interface Device) technology call MuShield to eliminate all interference from the Earth's Magnetic Field so that ultrasensitive R & D experiments will result in accurate findings.
* As MRI (Magnetic Resonance Imaging) technoglogy continues to evolve, leaders within the medical industry continue to trust and call upon MuShield to be the designer and supplier of critical mumetal magnetic shields

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ernesto
Sent: Thursday, March 26, 2020 2:36 PM
To: TekScopes@groups.io
Subject: [TekScopes] Any Tektronix magnetic shield for a CRT? A strange problem...

Has anyone a recommendation for a mumetal Tektronix shield that could fit an old CRT of 4 inch face plate, 2 inch neck and 13 inch length?

And... why hasn't Tektronix ever built a round face 4" CRT? It jumped from 3" to 5".....darn!

I experienced a strange problem with a small oscilloscope that I built 50 years ago and I am recalibrating now, and which has this odd 4" round non-flat CRT (the only cheap one I could find at that time, poor kid! ) At that time, I wrapped a metal sheet around the tube neck to magnetically shield it. I have no idea what metal this was. This "shield" was held with some old string, and to make it look more pretty I removed the string and replaced it with tape.

Then I started to experience a weird problem. The brightness of the trace was much lower at the start of the sweep. I broke my head analyzing the HV supply, the unblanking circuit, etc. etc. Maybe a leakage in the HV ceramic capacitors? Maybe the unblanking signal not uniform? I moved things around, and then the sweep was normal at the beginning and vanished at the end. Moving more things around, and then changing the horizontal position the trace disappeared at the left of the tube and was perfectly normal towards the right! The trace could always be adjusted for good focus and astigmatism.

Until I realized that I had been rotating this in-house "shield" cylinder. Fortunately....I found a position where the trace was back to normal. It must be that the unknown metal is magnetized! Had it been like this for 50 years?
I have no idea how the magnetization affected the CRT beam, if it hit some internal electrodes while preserving good geometry, but I know little about that CRT, not even its part number.

This is why I am looking for a CRT shield, if possible a Tektronix one, that has not been banged around. If it is not available, I might try to build one with some permalloy sheet, or forget about it and play with something else.

Thank you for your help, and hopefully you never experience such CRT beam problems (no attaching of big speakers to the side of your oscilloscope)

Ernesto





--
Dennis Tillman W7PF
TekScopes Moderator