Date   
Re: New 2465 Seimens brushless motor

victor.silva
 

I found out that the guy selling these Seimens motors got them from a storage unit auction.
Since he is from Portland OR, I assume the storage unit must have been from a Tek employee.

He did tell me that the same unit also had thousands of genuine police badges.
He was selling them on ebay also until those auctions were removed.
I think current badges cannot be sold, only obsolete ones.

He initially had almost one hundred of those motors in the original trays.

--Victor

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

greenboxmaven
 

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: 7104, fixing a few minor things

David DiGiacomo
 

On Thu, Mar 26, 2020 at 3:39 PM <sdturne@q.com> wrote:
1) Readout intensity only works in the "pulsed" position, triggered by +gate. I can adjust the readout brightness fully using the pot in the "pulsed" position.
This is quite a common issue on the 7104 and 7103. There has been
discussion of it here in the past, but I don't think anyone ever
tracked down the exact cause and cure.

On one of my 7104s I was able to sort of fix it by putting 1.2K in
parallel with R1922 and 1.1K in parallel with R1925, but I was never
exactly happy with that.

some of the previous threads:

https://groups.io/g/TekScopes/topic/7629541
https://groups.io/g/TekScopes/topic/7633990
https://groups.io/g/TekScopes/topic/7648866

7104, fixing a few minor things

@0culus
 

Hi all,

Hope everyone is well and avoiding cabin fever! Part of my cabin fever antidote is spending time in my lab. :o)

Anyway, some of you may remember that I picked up a very nice shape 7104 + plugins at a property auction a while back, for a cool $125. While the scope is ~99% in great working order, it's that final 1% that I'd like to see if I can deal with, pretty much minor things.

1) Readout intensity only works in the "pulsed" position, triggered by +gate. I can adjust the readout brightness fully using the pot in the "pulsed" position.

2) The readout disappears on a few timebase settings, mainly about midrange sec/div settings.

3) SIG OUT seems to not have usable output.

4) On certain faster timebase settings, the trigger point and some of the displayed waveform "disappears". Worth noting that my 7904A which also has a 7B15 in the delaying position also does this. Is it expected behavior?

I mainly want to ascertain if these are common issues with known solutions.

Thanks,

Sean

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

Re: Tek 222/224 Battery Replacement

g m
 

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://youtu.be/LJ2VS3aohV0.

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: TDS3000B calibration

David Kuhn
 

" To use some of your words, "you are confusing calibration with
adjustment".
Obviously the word Calibration mean different things to different people.
Calibration, at least how we did it at Tek in Europe, was almost always
Performance Verification. "

In my business, I always think of "Calibration" as an action verb. You are
calibrating or tweaking. Afterwards, you perform a "Certification" to
test the performance of the instrument. Hmmm, I guess that might be a verb
to, but not an much action - lol. The sheep skin does state "Certificate
of Calibration".

Dave

On Thu, Mar 26, 2020 at 8:03 AM zenith5106 <hahi@...> wrote:

On Wed, Mar 25, 2020 at 09:38 PM, benj3867 wrote:


Finally, @amirb, you are confusing calibration with performance
verification.
To use some of your words, "you are confusing calibration with adjustment".
Obviously the word Calibration mean different things to different people.
Calibration, at least how we did it at Tek in Europe, was almost always
Performance Verification. There were even two Calibration options for
customers
to choose from, PV or Adj, with different prices of course.
In the contract with our major customer it said that if a test was within
70%
of spec no action should be done. If it came out between 70 and 100% of
spec
adjustment should be done. If the adjustment failed to return it to less
than 70% or couldn't be done the instrument would still Pass. In either
case
it should be noted on the Certificate. And of course if the instrument was
out of spec and couldn't be brought back to within it would Fail the
Calibration.

/Håkan



Re: Tek 222/224 Battery Replacement

Miguel Work
 

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://youtu.be/LJ2VS3aohV0.

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: Trying to bring back a AA501

Rick
 

Eric, I have two of these AA501s. I curious to know how things are coming along. Did you go for the swapped part.

Rick

Re: Tek 222/224 Battery Replacement

Dave Voorhis
 

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://youtu.be/LJ2VS3aohV0.

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: TDS3000B calibration

 

On Thu, Mar 26, 2020 at 06:44 PM, amirb wrote:


no, no, of course not you, man!
I understood you weren't referring to me, Amirb!

I just tried to correct my earlier mistake: quoting the wrong part of a message.

Raymond

Re: TDS3000B calibration

amirb
 

On Thu, Mar 26, 2020 at 01:41 PM, Raymond Domp Frank wrote:


I made a mistake in my earlier reply re. amirb's post.

amirb wrote:

If you look down this thread, I tried to say the same thing but somebody
got
pissed for some reason!
Amirb, do you mean the part where I wrote " BTW, the repetition rate is
completely irrelevant for digital 'scopes"? I should add that it's as
irrelevant for analog 'scopes, apart from the fact that with the latter, trace
intensity suffers too much at lower repetition rates because of the lower duty
cycle.

Benj3867 seems to know that higher frequencies than specified cannot be used
because the automatic routine cannot handle them.

Raymond
no, no, of course not you, man!

Re: TDS3000B calibration

 

I made a mistake in my earlier reply re. amirb's post.

amirb wrote:

If you look down this thread, I tried to say the same thing but somebody got
pissed for some reason!
Amirb, do you mean the part where I wrote " BTW, the repetition rate is completely irrelevant for digital 'scopes"? I should add that it's as irrelevant for analog 'scopes, apart from the fact that with the latter, trace intensity suffers too much at lower repetition rates because of the lower duty cycle.

Benj3867 seems to know that higher frequencies than specified cannot be used because the automatic routine cannot handle them.

Raymond

Re: TDS3000B calibration

amirb
 

On Thu, Mar 26, 2020 at 01:21 PM, Raymond Domp Frank wrote:


On Thu, Mar 26, 2020 at 06:17 PM, amirb wrote:


If you look down this thread, I tried to say the same thing but somebody got
pissed for some reason!
Amirb, you mean that part? I haven't read all posts. I should add that it's as
irrelevant for analog 'scopes, apart from the fact that with the latter, trace
intensity suffers too much at lower repetition rates because of the lower duty
cycle.

Raymond
well, that was the tone I got from that message anyways...

I just looked up the TDS3000 manual, and it seems to me that they are using the pulser for tuning the channels' deskew
(hope i am using the term correctly) . They dont mention it in the manual but the setup shows why they needed the pulser

So the rise time is really not that critical as long as it is fast enough so the instrument can measure the delays between the channels
and adjust them. The more important and more expensive equipment in that setup in my view is having the 4 coaxial cables
with exact same electrical length and I believe they probably should be very phase stable

Re: TDS3000B calibration

 

On Wed, Mar 25, 2020 at 09:38 PM, benj3867 wrote:


Finally, @amirb, you are confusing calibration with performance verification.
The calibration process is not trying to measure rise-time or bandwidth
because these cannot be adjusted.
What makes you say that?

Raymond

Re: TDS3000B calibration

amirb
 


On Wed, Mar 25, 2020 at 09:38 PM, benj3867 wrote:


Finally, @amirb, you are confusing calibration with performance
verification.

Calibration means: first ""measuring"" a set of parameters from a standard calibration generator (rise time, DC gain, time interval, BW, etc....) and then
"adjusting" the instrument to bring those parameters within the predefined specs. Of course if the instrument
already meets the specs, you move on. So I dont think i was confusing anything with anything else...

Re: TDS3000B calibration

 

On Thu, Mar 26, 2020 at 06:17 PM, amirb wrote:


If you look down this thread, I tried to say the same thing but somebody got
pissed for some reason!
Amirb, you mean that part? I haven't read all posts. I should add that it's as irrelevant for analog 'scopes, apart from the fact that with the latter, trace intensity suffers too much at lower repetition rates because of the lower duty cycle.

Raymond

Re: TDS3000B calibration

amirb
 

On Thu, Mar 26, 2020 at 12:54 PM, Raymond Domp Frank wrote:


On Thu, Mar 26, 2020 at 03:48 AM, David C. Partridge wrote:


I've never encountered a fast edge calibrator (RT 150pS or so) that did even
1MHz.
Leo Bodnar's (no affiliation) fast pulse generators have 40ps max. rise time
and 10 MHz repetition rate. BTW, the repetition rate is completely irrelevant
for digital 'scopes.

Raymond
If you look down this thread, I tried to say the same thing but somebody got pissed for some reason!

Re: TDS3000B calibration

 

On Wed, Mar 25, 2020 at 05:35 PM, benj3867 wrote:


BTW, a suitable fast rise pulse generator can be easily built at home
following the instructions in appendix D of Linear Technology Application Note
47 by Jim Williams (easily found on the web).
It depends on what is needed. A pulse generator like John Williams' is suitable for checking or adjusting slew rate, which means maximum HF content. That is not the same as adjusting for optimum bandwidth, where a step response allows adjustment for flat frequency characteristics.
I doubt whether Jim Williams'pulser would produce satisfactory results or even work with the automatic adjustment routine for a TDS3000-series 'scope. At least, the pulse would have to be lengthened and flattened (using an airline, piece of coax or the like). For the same reasons, a PG506 works fine for adjusting the vertical amp of a 'scope (where 0.7 - 1000 ps rise time is fast enough) and the PG502, with comparable rise time isn't, because of the far less controlled waveshape of the PG502.

BTW sorry for mentioning Leo Bodnar's pulser in an earlier post. At the time, I hadn't seen that it was mentioned before.

Raymond

Tek 222/224 Battery Replacement

Jeff Davis
 

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://youtu.be/LJ2VS3aohV0.

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