Date   

Re: Tek 2230, Alternatives to the cursor control pot.

Albert Otten
 

On Sun, Jul 4, 2021 at 05:34 PM, Pitpat wrote:


The point is that I couldn't find any direction on how the original
potentiometer works, from my understanding the dual 10k ohm variable works in
opposition so that there's no "dead zones" caused by the 360 degrees of
rotation but thats all...
Hi Federico,

Any progress so far?
It's true that the pots work in opposite directions. In my 2232 this is achieved by interchanging assignment of 0V and +5V to the terminals. With an ordinary dual pot this would not prevent dead zones to occur simultaneously for both wipers. The trick here is that one wiper is rotated w.r.t. the other. Not over 180 degrees what I expected, but enough to avoid simultaneous dead zones.
When there are no simultaneous dead zones the processor can always determine the direction of knob rotation. I don't see the purpose of opposite directions.

Albert


Re: Looking for an T5611-25 CRT (or -7 or -2)

Keith
 

Hi Bob,

If you really need a 561b CRT, then the TEk part number you would seem to need is 154-0614-00

That’s external graticule, Standard p31 phosphor and Standard B14-38 basing.

Note that the -01, -02 and -03 versions of this 154-0614-xx part number are electrically and physically the same, except P2, P7, and P31 phosphors

Is your CRT ceramic? Can you accept a glass CRT?

If so, there is an electrically equivalent earlier CRT, in glass, the T5032. There are about eleven TEK T5032 part numbers that would appear to me at first glance to work, if the glass vs. ceramic thing doesn’t blow up your world.

See them, here: https://w140.com/tekwiki/wiki/T5032

The first eleven p/n have external graticule. Some phosphors are “better” for you than others.

I see at least one complete 561b on fleabay - being parted out. That’s here, and looks like it might be an external graticule CRT.

https://www.ebay.com/itm/192947024206?_trkparms=ispr%3D1&hash=item2cec89f14e:g:2G0AAOSwqrNgCbE1&amdata=enc%3AAQAGAAACkPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSd3M8ngECaRA0SmyU4KT%252FnoWoOfkiFaIW2SJ8lxc2ql%252Bb5XWyxfgDJaThucyAKkrugV0zON4FNfd7a6vwaJdBMsTZkoiO6Jh%252BlD8lWxl90KMRRKnk4jNtjM8BnNwk%252BQ8z9e0HakfOXn9jQ0JiF7vDVG7opKEeF%252B9efKKpTnfnEwIiBWStepSxEWv%252FuSo8zjqpQPOP%252FaiPxd%252Bvp3y4fSezT8OnjmYWzwfzqXgRHuWqb85h6FzSu5j%252FPPgFbIiq2MFCsHOW4y8YCmJyJJDWBfnpA1SyeuZFtmzLLuVsLStUfvwWEDg9RK%252FT1abwuCxYvr%252BzzCp6cfdWjMh1ph3dnAoJHMGljHdYfO4jjXqsXWHn3e78xK%252B2aPcS18m3Etv7YaQgkbgHej587Al7sJqV0gexCevefT2Rv3DG7VopNJqbaDLxLiLAyeuqFX40vbwwEB8ruYUhwfOwaKc%252FYJ2EMjwI7hQIPbP0NwRlbg9geHHe0mzd6%252FGaKz9gt4NYzPju9tkEU5J9MiAlp8uDRNuZpr2FC3AhzfCcM21HLaOMEmyxnqQSaC3Hf4tGD2SJLIEgJSnrZWTGU9ifzRfbO%252BOXohPymi%252ByJFbvWibs01vmF0od4HHmb6nEA%252B%252BmPEQ%252FRfWFQaKracYWfVBH9jCRL1Bc86%252Bm4T5iKMneKGHsHRBejgLV8XsyrGX0ov8p0tKVPOpxQcRXMWeAk1gdVVKNX7DdwrFM6eS%252BFjYJncYqIFgZTbxH%252Fj3IlRkP2oqyehJf58paouetUd1uCgeciNBQIqsd9ieegBQ7V9A1Oh%252FdT9gqJVk6YqPjp9a8dgeBtyeK7rWZM%252Bt3%7Campid%3APL_CLK%7Cclp%3A2334524

Hope this helps


Re: Calibrate the time base, or horizontal amplifier?

Tom Phillips
 

My understanding is that the frame calibration is to ensure the scope
frames are identically calibrated which you would want if swapping plugins
between frames.


TDS-540B Repair?

Christopher Maness
 

The CRT went intermittent with brightness and vertical spread last week. I put it in my car hopping that a friend of mine would take a look at it. He did not want to bother, so it rode around in my car in the heat. The hot bumpy car ride seems to have fixed it at least temporarily, so it could be something simple like card contacts a little dirty. It also took an ESD hit on channel 1. The channel still works, but is no longer high impedance. Was wondering if there is a good tech in the SoCal area. If not, I am willing to box it up and send it to one based on recommendations.

Thanks,
Chris Maness


Re: Dennis Tillman

 

Yeah, a fall detector is definitely something you should buy if you're
concerned. It doesn't cost so much and it's definitely comforting and
helpful.

On Mon, Jul 12, 2021 at 10:06 AM Tom Gardner <tggzzz@...> wrote:

On 12/07/21 02:53, Richard R. Pope wrote:
I am up there in years and my body no longer works correctly. I could easily
fall and hurt myself and not be able to call for help!
That's a common problem. Over here there are services where you have button on
your wrist or around your neck, and a box connected to the phone line. If you
press the button it calls a service centre and someone comes to help. My mother
had one for years, and it was a great comfort to ME :)

There are also many other devices available, e.g. those which sense movement in
the building (to verify you are up and about) and accelerometers that detect falls.





Re: Calibrate the time base, or horizontal amplifier?

emissionlabs
 

Thank you for the many inputs.

I am looking for a way to calibrate this 5113 scope without dedicated calibrators. Otherwise it becomes too much for me, just for this one time action. I can use an Agilent 33120A digital controlled oscillator, and a 34301A 6 digit multimeter with build in frequency counte, a stabile DC power supply and an HP pulse generator. Even the build in 100Hz signal calibration signal, derived from the mains is a good time reference.

I can input signals directly on the scope boards if needed, or tap signals there. I understand with a 100MHz scope it can not be done like that. The 5113 is just a low frequency scope, and the equipment I have can do much higher frequency than the scope itself.

Having repaired the HV circuit, it is not possible to say what the HV was before, but it was over 3530V after the repair. So I set it to 3400V, by the book. Changing the HV, from what I know, does change the size of the projected picture on the CRT.

Any good hints before I start are much appreciated.


Re: What do you do when you get a call from AUSTRALIA

 

Hi Dennis,
I'm so glad you were helped by a member who took the time to give you a call - probably at great expense.

I had a bad accident in 2005 that changed my life. Several people I interacted with on another web site where I am a moderator sent me messages, and that helped. What really helped was a two pronged thing. First, some called me as you were called. The best thing was I resumed helping people on that web site. The very best medicine is helping total strangers - or acquaintances with your skill set.

Today I am able to do more, but has severe limitations to deal with. My wife died a year and change ago, but continuing to help people has allowed me to get through all this. Today I have a girlfriend and things are looking pretty good. This would not be possible without the opportunity to lend a hand to my fellow human being. Just know you are appreciated and people care for your well being. You do make a difference in people's lives Dennis.

-Chris


Re: Dennis Tillman

Tom Gardner
 

On 12/07/21 02:53, Richard R. Pope wrote:
I am up there in years and my body no longer works correctly. I could easily fall and hurt myself and not be able to call for help!
That's a common problem. Over here there are services where you have button on your wrist or around your neck, and a box connected to the phone line. If you press the button it calls a service centre and someone comes to help. My mother had one for years, and it was a great comfort to ME :)

There are also many other devices available, e.g. those which sense movement in the building (to verify you are up and about) and accelerometers  that detect falls.


Re: Calibrate the time base, or horizontal amplifier?

Peter H
 

The "official" way is to use a 067-0680-00 calibration plug-in (https://w140.com/tekwiki/wiki/067-0680-00, the 067-0587-xx is the same for the 7000 series) to adjust the mainframe first.
Without one, you could in principle feed a signal in through the amplifier, and adjust its amplitude (as measured on the scope's backplane) to the specified V/div - but you'd have to be really sure you know how to get this right.

The '680 produces a stair-step signal that really helps getting the geometry right, of course a suitably configured arbitrary generator could be substituted.

I would still recommend the '680, maybe you can borrow one from someone on the list.


Re: What do you do when you get a call from AUSTRALIA

Mlynch001
 

Dennis,

So happy to learn that you are doing better. Praying that you can stay out of the spiral that is debilitation depression.

Sincerely,
--
Michael Lynch
Dardanelle, AR


Re: What do you do when you get a call from AUSTRALIA

Tom Lee
 

Dear Dennis,

All of us are relieved and happy to hear from you -- thank you for posting!

As to the Dark Cloud Demon, I recommend more geeking out with your many friends here, to supplement your meds.

-- 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 7/11/2021 21:37, Dennis Tillman W7pF wrote:
Yesterday was a really nice day.
The temperature was perfect, the sun was out.
I was on the deck of our little summer house working on my computer.
In front of me across an inlet of Puget Sound I can see snow covered Mt
Rainer 40 miles away.
Suddenly my cell phone rings.
Annoyed! I pick it up to look at the screen and it says in all capital
letters:
AUSTRALIA
Underneath that seemingly giant word is a strangely formatted phone number.
That strange format could only belong to an international telephone number.

This is exactly what my brain said to me in the next 2 seconds between the
2nd and the 3rd ring.
"Holy Crap!"
"It's a mistake"
"I don't know anyone in Australia"
"It's a robo-call. It must be"
"Wait a minute, nobody makes robo-calls from Australia"
"The number format means it really might be coming from Australia"
"Why would anyone want to call me from Australia"
"It's a new trick by the robo-callers to get people to answer and listen to
their recordings"
"They must have mis-dialed"
"They accidentally sat on their phone and pressed a bunch of numbers at
random"
"I don't know anyone in Australia" (that was the second time my brain said
this to me to make sure I got the point)

Then my brain shut up for a moment while it waited to see what I would do
next.
I realized someone probably went to a lot of trouble to find me. So I
answered.

ARGH! It was someone from TekScopes who was very concerned that I was OK
because I disappeared about 4 weeks ago without a trace. We had a very long
talk about what was going on. I was in a depression and couldn't get out of
it. I was overwhelmed with all the things going on in my life - most of them
it seemed to me were going badly. I have suffered from depression almost my
entire life. Until I was in my late 40s I had no idea this was the case. By
then I spent several years in therapy with several different therapists and
eventually one Psychiatrist I was seeing worked out the right balance of
medications for me to take for the rest of my life to help me avoid falling
into another depression. Depression is a learned behavior and the real
danger about it is that the more it happens to you the easier it is to
become depressed. Once I am in one it is like a trap and I can't get out.

But the phone call and the conversation I had with the caller - he said his
name so fast I didn't have a chance to get it was wonderful. He understood
completely what I was going through. That call made it possible to spend
most of today catching up on my email and facing the world once again. I'm
still a little shaky (mentally) but I think (I hope) I will be on my feet
again (mentally) in a few days.

In the meantime I would like to thank Michael Dunn for covering for me. He
and I both agree I could use help with TekScopes because it beginning to
take up too much of my time (that was one of the things I was not able to
spend enough time on but I didn't know how to fix it).

Give me a few days to get caught up
Dennis Tillman W7pF
Thank you for your concern!!!
That really means a lot to me.
I'm happy to be back!!!
Who was it that called me all the way from Australia. I need to thank them
personally.







Re: What do you do when you get a call from AUSTRALIA

EricJ
 

Dennis, glad you are feeling better, I hope you continue to feel even better. I have been there myself with health issues and getting like things would never get better, so I know how it goes sometimes. The gentleman who rang you up was Chris van Lint. We were all happy to hear from him that you were all right.--EricSent from my Galaxy

-------- Original message --------From: Dennis Tillman W7pF <dennis@...> Date: 7/11/21 11:38 PM (GMT-06:00) To: TekScopes@groups.io Subject: [TekScopes] What do you do when you get a call from AUSTRALIA Yesterday was a really nice day. The temperature was perfect, the sun was out. I was on the deck of our little summer house working on my computer. In front of me across an inlet of Puget Sound I can see snow covered MtRainer 40 miles away. Suddenly my cell phone rings. Annoyed! I pick it up to look at the screen and it says in all capitalletters:    AUSTRALIAUnderneath that seemingly giant word is a strangely formatted phone number.That strange format could only belong to an international telephone number. This is exactly what my brain said to me in the next 2 seconds between the2nd and the 3rd ring."Holy Crap!""It's a mistake""I don't know anyone in Australia""It's a robo-call. It must be""Wait a minute, nobody makes robo-calls from Australia""The number format means it really might be coming from Australia""Why would anyone want to call me from Australia""It's a new trick by the robo-callers to get people to answer and listen totheir recordings" "They must have mis-dialed""They accidentally sat on their phone and pressed a bunch of numbers atrandom" "I don't know anyone in Australia" (that was the second time my brain saidthis to me to make sure I got the point)Then my brain shut up for a moment while it waited to see what I would donext. I realized someone probably went to a lot of trouble to find me. So Ianswered.ARGH! It was someone from TekScopes who was very concerned that I was OKbecause I disappeared about 4 weeks ago without a trace. We had a very longtalk about what was going on. I was in a depression and couldn't get out ofit. I was overwhelmed with all the things going on in my life - most of themit seemed to me were going badly. I have suffered from depression almost myentire life. Until I was in my late 40s I had no idea this was the case. Bythen I spent several years in therapy with several different therapists andeventually one Psychiatrist I was seeing worked out the right balance ofmedications for me to take for the rest of my life to help me avoid fallinginto another depression. Depression is a learned behavior and the realdanger about it is that the more it happens to you the easier it is tobecome depressed. Once I am in one it is like a trap and I can't get out. But the phone call and the conversation I had with the caller - he said hisname so fast I didn't have a chance to get it was wonderful. He understoodcompletely what I was going through. That call made it possible to spendmost of today catching up on my email and facing the world once again. I'mstill a little shaky (mentally) but I think (I hope) I will be on my feetagain (mentally) in a few days.In the meantime I would like to thank Michael Dunn for covering for me. Heand I both agree I could use help with TekScopes because it beginning totake up too much of my time (that was one of the things I was not able tospend enough time on but I didn't know how to fix it).Give me a few days to get caught upDennis Tillman W7pFThank you for your concern!!! That really means a lot to me.I'm happy to be back!!!Who was it that called me all the way from Australia. I need to thank thempersonally.


Re: What do you do when you get a call from AUSTRALIA

 

Dennis,

We are all glad that you are well, aside, of course, from the depression, and we look forward to reading you entertaining entries on the group (this one being no exception, well written and amusing).

Depression is a hell of a thing. It contrives to make you think that the pathological way you feel is entirely justified and rational, and even when you KNOW that you suffer from depression, the lies it tells you are still damn convincing.

Depression is a big part of why I wound up on TekScopes. I too have suffered from it most of my life (ever since adolescence) and it was really getting the better of me about half way through the pandemic lock down. It was keeping me up all night, and in an attempt to deal with the sadness I started digging through my father's effects. Almost the first thing I found was Motorola 6809 single board computer that my father had purchased in the late 70s and used to teach himself about microcomputers. In order to debug this ancient bit of technology, I dragged out my father's oscilloscopes (a 475 and a 2213) and began poking around the CPU bus to see what was what.

Everything was going swimmingly for a few weeks until one day the 475 lost it's horizontal sweep. While researching how to repair the sweep circuit on the 475 I discovered the TekScopes group, and the rest is a tale of almost entirely unalloyed joy. However, I have gone through several bouts of depression since joining he group last year, often coinciding with a failure to repair one or another instrument I have acquired since joining TekScopes. There was one bout that was precipitated by a scope that was destroyed in shipping, and another by my failure to make progress repairing the 7623A. I don't actually believe that the depression is the result of these failures and setbacks, but that it latches onto them and amplifies the feelings of disappointment and inadequacy, and things can rapidly spiral out of control from there.

It's good that you have found medication that works, but I have also found that a little positive human contact works wonders as well. We do appreciate all that you do for this community. I also appreciate your writing, which has a delightful blend of expertise and humor, and look forward to finding each new post by you in the group.

-- Jeff Dutky


Re: RSA 3408 A Real time spectrum analyser

Anil Nediyara
 

Thank you. Will chk the electrolytic caps and back up the hdd image. It has almost all the options enabled, was a demo equipment for the technical sales team of Tektronix here.


Re: What do you do when you get a call from AUSTRALIA

Richard R. Pope
 

Dennis,
GOD Bless you!
rich!

On 7/11/2021 11:37 PM, Dennis Tillman W7pF wrote:
Yesterday was a really nice day.
The temperature was perfect, the sun was out.
I was on the deck of our little summer house working on my computer.
In front of me across an inlet of Puget Sound I can see snow covered Mt
Rainer 40 miles away.
Suddenly my cell phone rings.
Annoyed! I pick it up to look at the screen and it says in all capital
letters:
AUSTRALIA
Underneath that seemingly giant word is a strangely formatted phone number.
That strange format could only belong to an international telephone number.

This is exactly what my brain said to me in the next 2 seconds between the
2nd and the 3rd ring.
"Holy Crap!"
"It's a mistake"
"I don't know anyone in Australia"
"It's a robo-call. It must be"
"Wait a minute, nobody makes robo-calls from Australia"
"The number format means it really might be coming from Australia"
"Why would anyone want to call me from Australia"
"It's a new trick by the robo-callers to get people to answer and listen to
their recordings"
"They must have mis-dialed"
"They accidentally sat on their phone and pressed a bunch of numbers at
random"
"I don't know anyone in Australia" (that was the second time my brain said
this to me to make sure I got the point)

Then my brain shut up for a moment while it waited to see what I would do
next.
I realized someone probably went to a lot of trouble to find me. So I
answered.

ARGH! It was someone from TekScopes who was very concerned that I was OK
because I disappeared about 4 weeks ago without a trace. We had a very long
talk about what was going on. I was in a depression and couldn't get out of
it. I was overwhelmed with all the things going on in my life - most of them
it seemed to me were going badly. I have suffered from depression almost my
entire life. Until I was in my late 40s I had no idea this was the case. By
then I spent several years in therapy with several different therapists and
eventually one Psychiatrist I was seeing worked out the right balance of
medications for me to take for the rest of my life to help me avoid falling
into another depression. Depression is a learned behavior and the real
danger about it is that the more it happens to you the easier it is to
become depressed. Once I am in one it is like a trap and I can't get out.

But the phone call and the conversation I had with the caller - he said his
name so fast I didn't have a chance to get it was wonderful. He understood
completely what I was going through. That call made it possible to spend
most of today catching up on my email and facing the world once again. I'm
still a little shaky (mentally) but I think (I hope) I will be on my feet
again (mentally) in a few days.

In the meantime I would like to thank Michael Dunn for covering for me. He
and I both agree I could use help with TekScopes because it beginning to
take up too much of my time (that was one of the things I was not able to
spend enough time on but I didn't know how to fix it).

Give me a few days to get caught up
Dennis Tillman W7pF
Thank you for your concern!!!
That really means a lot to me.
I'm happy to be back!!!
Who was it that called me all the way from Australia. I need to thank them
personally.








What do you do when you get a call from AUSTRALIA

 

Yesterday was a really nice day.
The temperature was perfect, the sun was out.
I was on the deck of our little summer house working on my computer.
In front of me across an inlet of Puget Sound I can see snow covered Mt
Rainer 40 miles away.

Suddenly my cell phone rings.
Annoyed! I pick it up to look at the screen and it says in all capital
letters:
AUSTRALIA
Underneath that seemingly giant word is a strangely formatted phone number.
That strange format could only belong to an international telephone number.

This is exactly what my brain said to me in the next 2 seconds between the
2nd and the 3rd ring.
"Holy Crap!"
"It's a mistake"
"I don't know anyone in Australia"
"It's a robo-call. It must be"
"Wait a minute, nobody makes robo-calls from Australia"
"The number format means it really might be coming from Australia"
"Why would anyone want to call me from Australia"
"It's a new trick by the robo-callers to get people to answer and listen to
their recordings"
"They must have mis-dialed"
"They accidentally sat on their phone and pressed a bunch of numbers at
random"
"I don't know anyone in Australia" (that was the second time my brain said
this to me to make sure I got the point)

Then my brain shut up for a moment while it waited to see what I would do
next.
I realized someone probably went to a lot of trouble to find me. So I
answered.

ARGH! It was someone from TekScopes who was very concerned that I was OK
because I disappeared about 4 weeks ago without a trace. We had a very long
talk about what was going on. I was in a depression and couldn't get out of
it. I was overwhelmed with all the things going on in my life - most of them
it seemed to me were going badly. I have suffered from depression almost my
entire life. Until I was in my late 40s I had no idea this was the case. By
then I spent several years in therapy with several different therapists and
eventually one Psychiatrist I was seeing worked out the right balance of
medications for me to take for the rest of my life to help me avoid falling
into another depression. Depression is a learned behavior and the real
danger about it is that the more it happens to you the easier it is to
become depressed. Once I am in one it is like a trap and I can't get out.

But the phone call and the conversation I had with the caller - he said his
name so fast I didn't have a chance to get it was wonderful. He understood
completely what I was going through. That call made it possible to spend
most of today catching up on my email and facing the world once again. I'm
still a little shaky (mentally) but I think (I hope) I will be on my feet
again (mentally) in a few days.

In the meantime I would like to thank Michael Dunn for covering for me. He
and I both agree I could use help with TekScopes because it beginning to
take up too much of my time (that was one of the things I was not able to
spend enough time on but I didn't know how to fix it).

Give me a few days to get caught up
Dennis Tillman W7pF
Thank you for your concern!!!
That really means a lot to me.
I'm happy to be back!!!
Who was it that called me all the way from Australia. I need to thank them
personally.


Re: RSA 3408 A Real time spectrum analyser

nj902
 

It is a very nice instrument, fast and accurate. The windows OS makes it easy to save screen images and other data to USB devices. Option 21 is very helpful.

If you get it, I suggest that you open the unit and inspect the electrolytic capacitors in the power supply and on the CPU board. They are prone to failure.

You should also capture an image of the hard drive.

Here is the datasheet: https://download.tek.com/datasheet/37W_18380_4_1.pdf


Re: Calibrate the time base, or horizontal amplifier?

Harvey White
 

I'm not sure if I'll go that far.  I have some 468's, two 5000 series scopes, a 7704a, 7904, and a 7103 and 7104.  (let alone a few other scopes).  I've got a PG506, TG501, SG502 and SG503. I have the signal standardizers for up to 400 Mhz (the -01, I think).  Oddly enough, I have a fluke 343A, and I think it's a Fluke 331A voltage/current calibrator as well.

I have a very old, and very odd weston meter calibrator that was designed for calibrating moving needle meters.  The nice thing is that it will put out the 600 or so volts AC frequently needed to calibrate a DVM.  Using a "calibrated" meter allows duplicating results.  Don't think that the DM5101 needs variable frequency, but likely 400 Hz or so.  I have to completely redesign the CPU board to get any of mine to work, another project, though.

Too busy writing display drivers for LCD displays (ARM) for the moment, although that work will go into a few projects.

Harvey

On 7/11/2021 10:40 PM, Zentronics42@... wrote:
Hi Harvey,
Well if there is a list of people that calibrate a scope to that extent. I will have to add my name to the list. I ended up building the lab based on the 7000 series scopes (7603 X2,7854,and 7904, and many associated plugins) but I had a chicken and egg issue. I got the scopes and plugins from eBay cheap but I did not trust them. A while later I ended up with both sets of cal standards the TM500 and the type units I still have a bit of work to do on the SG504 the high range is not working but low is. So I have done the full calibrations and everything is up to spec. It is a DEEEEEP rabbit hole that starts at a SG503 and ends at a type 284 and hits time mark and amplitude calibrators along the way. However in the service manuals the low frequency and high frequency compensations of the amps are done with square waves or various rise times and frequencies mostly around 1khz,10khz,100khz, rise times 1ns and higher for the high frequency compensations. I had to cal the calibrators before I used them so bas accuracy is against a Keithley 6500. All this was made reasonable when I called Tek for a calibration request. For a 465 they quoted me $100.00. for the 7603 frame $800 for a 485 $1200.00. I did not even ask about the 7854 and the 7904A. but given that I have done 3 7603’s a 7704A a few 465’s and 2 485’s as well as a partial on a 7854 ( need to recreate a board to complete that one unless the thermal calibration of the verticals is not that important don’t know yet. ) the gear was worth the investment. And the knowledge gained in doing the calibrations has been priceless.

In terms of AD/DC I have a fluke 343A for DC and a Fluke 5200A with the 5205A amplifier. The good news is for your needs you can get just the 5205A as it has a fixed gain and put the correct signal in the front end of it. If I remember correctly it is a gain of 100 so 60 V signal will output 600 Vac. As to for cost I don’t know. I paid $700 for both units broken. The amp was fine, however the 5200A -190V rail had burned up and the power amp in the 5200A needed to be rebuilt. Needed these to calibrate the 6 DM502’a. 6 DMMs is overkill however when working on the Tek multi rail power supplies it can be really convenient to watch them ALL at once. On thing to note on the meter cal does it need variable frequency? The 5200A with the 5205A can do 0-1200 Vac 10 Hz to 1 Mhz. Haven't needed to play with 1200Vac @ 1Mhz yet that is a bit spicey.

Zen
-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Harvey White
Sent: Sunday, July 11, 2021 8:56 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Calibrate the time base, or horizontal amplifier?

I'm not sure how well I can hear you, your voice is a bit echo-y from the bottom of that rabbit hole.

IMHO, what most people seem to worry about is horizontal and vertical accuracy, time and amplitude. You're quite correct that checking out the frequency response is difficult. The SG502 and SG503 are constant amplitude generators (at least the SG503 and SG504), and those can be used for frequency calibration. There are workarounds for fast risetime squarewave generators, which can be built easily. How much is a Fluke 5200? Thought they needed an amplifier for the high voltage output on AC. I personally can do DC 0-2 amps and 0-1KV. AC is a problem.

I do wonder how many people will calibrate a scope to that extent, unless the scope simply won't work without those sources. (the DM5101
*needs* a 600 volt measured AC source, but it's not a scope).

Harvey


On 7/11/2021 6:26 PM, Zentronics42@... wrote:
Harvey,
One of the main calibration issues that requires "exotic" signals Is the frequency calibration of the amplifiers. Having these be off can nuke the bandwidth of the scope. 465B 3db down 75-80 Mhz instead of 135 Mhz. (Yes I know 135 is above the 100 Mhz rating of the scope but that is what mine caled up to when properly adjusted.) These are done with fast edge square waves. 1ns rise time for 465 and under, ps rise time for 485's and faster for even further up the BW scale. But in terms of an AC calibrator a fluke 5200A would not be bad with its amp 5205A can go to I"1500 Vac. Which is a bit spicey. If using a meter something that needs to be taken in to account most good meters work in AC RMS scopes work in PK-PK so appropriate calculations need to be taken in to account when setting up the signal source. In terms of calibration a functioning and calibrated TG501, PG506, and SG503 will cover 99% of the scopes up to 100 Mhz. Over that will need "exotic" signal sources tunnel diode pulsers and such. I will admit I have seen the bottom of that rabbit hole it is kind of on the deep side.

Zen

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Harvey
White
Sent: Sunday, July 11, 2021 6:14 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Calibrate the time base, or horizontal amplifier?

Not sure that they ever made one for the 5000 series, but an input standardizer would give you direct access to the frame, which would be fine if you had a known AC amplitude to calibrate the frame.

You'll only be able to get close, but remember that a scope is good to 3 to 5% anyway.

I'd be tempted to find an accurate AC source. A good meter would help, square waves would be best, but you'd need to adjust for the waveform if you're using a meter.

If you could feed a signal directly into the frame, then that allows you to calibrate both the H and V amplifiers.

If you have only the one frame, or only the one plugin, then I'd be tempted to take the mainframe's calibration on the Y channel as valid (arbitrary, I know), then adjust the vertical plugin to read the appropriate p-p value on the scope.

Then swap the H and V plugins (should be allowed, please check), but then adjust the H frame gain to the same deflection.

Then swap the plugins back to H and V. Adjust the H timebase for the appropriate scale.

that ought to get you close.

That's what I'd do. Adjusting the power supplies pretty much requires a recalibration.

A time mark generator can be made with some TTL logic and a TTL oscillator chip.

There are some amplitude calibrators used for a DMM that would give you at least a good 10 volt reference, so that range would be ok, but you'd find it difficult to check the other ranges.

Harvey


On 7/11/2021 5:28 PM, emissionlabs wrote:
Hello,

I need a little guidance, and don't want to make misakes while fixing a 5113 Dual Beam Scope. The 3400V high voltage was gone, and when I fixed that, the chopper circuit appeared bad, and when then was fixed, there was only one beam. Not mentioning a few smaller defects. But I have it all fixed now, and it works very good. Sharp traces, and very nice geometry.

I have adjusted the high voltage nicely at 3400V. +/-30V is as good as the single turn pot meter can do. +/-170V is allowed. Probably the HV is not exactly the same as it was before, and this affects the picture size, and if so, horizontal and vertical gain calibration needs to be done. I have two time base modules with it, which do not show the same result on the calibrator of the scope itself. So at least one of them is out of calibration. The horizontal trace is a tiny bit too slow, which can be caused by the horizontal amplifier being set wrong, or the time base being set wrong. I do not have a time mark generator, but I have an accurate hewlett packard pulse generator, which probably can do the same. And also we have 50 Hz here, and the internal calibrator shows exactly 100Hz. So a good reference is not the problem.

At this point I get stuck a little bit because I could set the horizontal gain a little bit higher, or set the time base a little bit faster. Both would "cure" the problem. But it feels wrong to set the time base faster, while in fact the horizontal amplifier would be out of calibration, or vice versa.

I have neve done this before, and I don't want to mess it up. It is such a crispy sharp CRT for the rest if it, I would like to get this scope in good condition. Perhaps someone has good advice for me. Thanks in advance!
























Looking for an T5611-25 CRT (or -7 or -2)

Bob Rosenbloom
 

I know this is a long shot, but I'm looking for an T5611-25 CRT for use in restoring an DEC LINC-8 minicomputer.
It used a modified Tektronix 561B oscilloscope, with DEC plug-ins, and the P25 phosphor CRT with no graticule.
The one in the LINZ has a badly burned face. A P7 or even P2 phosphor would also work though would look
different than the original. So basically any slow phosphor and no graticule.

Some cell phone photos of the LINC and scope are on my web site here:
http://www.dvq.com/dec-linc8/


Re: Fixing a 7603 Power Supply

 

Eric,

Thanks. I found one on the auction site, and I’m going to disassemble the pot I have in hand and see what I can do to clean and repair it while I wait for the replacement part to arrive.

The part I have in hand is one of the mod pots that is assembled with screws rather than rivets, so it will be easy to take apart. The cleaning and lubrication has been discussed previously and I’m reading through those posts now.

I’m also looking at the power switch, which is very hard to turn on (it’s a pull style switch). QService has a replacement for sale, but I’d like to fix the one I have, if that’s possible.

— Jeff Dutky

10641 - 10660 of 194748