Date   

Re: Greetings From a New Member

snapdiode
 

Welcome. Sadly you chose a bad time to enter the hobby, the people who can rebuild the 547 HV transformer are no longer active AFAIK, and the offer on vintage Tek plugins and accessories has dried up.

There used to be many plugins on eBay, even the samplers and spectrum analyzers, active probes, etc.

Now it's all in someone's closet.

OTOH, Russian tunnel diodes are massively available.


Re: Greetings From a New Member

stevenhorii
 

Gordon,

Welcome from someone like you whose career (I'm a radiologist - but it is a
pretty high-tech branch of medicine and we do learn a lot about radiation
dosimetry and safety) did not draw me to the realm of vintage electronics.
Some of the interest in Tektronix stuff was that they treated me very well
when I was a kid and wrote to them asking for a catalog and they mailed me
one. At the time, I likely could not have afforded anything in the catalog.
My first Tek scope was a 535 purchased from the DoD when they ran surplus
disposal themselves instead of contracting it out. Other interests - space
program electronics, microscopes, and time and frequency stuff - have
resulted in a basement and garage full of stuff. If my wife did not at
least tolerate it, she would have been gone a long time ago. I try to keep
my deal with her - no junk above the basement unless it's something she
thinks looks interesting. So I have a Mars Mariner rocket engine in the
shipping frame as an end table and an Apollo "Q-ball" from the top of the
emergency launch escape system sitting in the living room. She likes the
look of those. I mentioned this here before, but our first date was to a
surplus store.

I think many of us who trade stories and useful info in this group are
similarly affected. Oh, and documentation (manuals, catalogs, etc.) are
also a must - seems to be part of the "syndrome".

Steve Horii

On Tue, Dec 8, 2020 at 10:43 PM Gordon Smith <gfsmith@cox.net> wrote:

Hi Jon,
You are correct Sir. General Atomics developed Nuclear Reactors in the
1950's and had a very advanced, for it's time, experimental Gas Cooled
Reactor in the 60's that unfortunately did not get to commercial
production. There claim to fame in the nuclear field is that they still
offer and support the TRIGA Research Nuclear Reactor (
https://en.wikipedia.org/wiki/TRIGA ) that was Designed under Freeman
Dyson (with Edward Teller advising). Regarding the TEK scopes being
addicting, I can understand. I have always been a devotee of elegant design
and the Vacuum tube based Tek scopes are just gorgeous examples of elegant
design.

Regarding photos of the NLS VM's. I may be able to provide some. I have
examples of the two total extremes of their voltmeters. One is from the mid
50's, vacuum tubes everything with stepper motor actuation of the Edge Lit
Display (It's my second heaviest piece of test equipment behind the Tek
547). A US Air Force contract Volt meter. And the other is a Model 2900
from the late 60's with discrete semiconductors for everything. Fun Pieces
of equipment.

Thank You for the Bandwidth,

Gordon






Re: Greetings From a New Member

Dave Seiter
 

The 502 was my first Tek scope too, and also the reason for joining the group!  I got great advice on fixing it, but got sidetracked by two pallets of other Tek scopes soon thereafter...  One of these days I hope to get back to the 502.
-Dave

On Tuesday, December 8, 2020, 09:57:06 AM PST, Gordon Smith <gfsmith@cox.net> wrote:

Hi All,
Just wanted to introduce myself. I'm Gordon Smith, a technology
enthusiast down here in San Diego, CA. Was recently given a Tek 502
Dual Beam Oscope and in researching it found your group. A Tek 547
with cart and three plug ins was also adopted (yes, it's got the
dreaded HV transformer issue). Other than being dragged willingly
into the vintage Tek Oscope cult, I enjoy Vintage technology like ham
radio stuff (want to the learn Morse code. Have way too many radios),
Test equipment (I have some wonderful Non-Linear systems edge lit
voltmeters) and have wayyyyy too much....errr...."Stuff" in the
garage. I'm a mechanical engineer by trade doing mainly R&D over many
fields and was forced by circumstance to learn a lot of electrical
and some electronics. Currently employed by General Atomics. Thank
you for allowing the introduction and stay safe out there. Gordon


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

Jim Ford
 

LOL!  Don't give my wife any other names to call me!    Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: toby@telegraphics.com.au Date: 12/8/20 7:03 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] SUCCESS! The "sick" 475A is now the "fixed" 475A! On 2020-12-08 9:01 p.m., Jeff Dutky wrote:> Dave Paterson wrote:>>>> I'd say this deserves a new topic under calibration, but I wouldn't want to loose the connection to all this good info in this one.> > I intend to post my write up of this discussion, along with a summary of the 475/475A calibration procedure using the suggested replacement equipment, under a new topic (Scope Calibration Using Home Brew Equipment? I'm open to suggestions). I was actually going to ask for your input on the service manual calibration procedures, so that we could extend the document to include more than just the 475/475A (and maybe some of the 2200 scopes, but I'd rather not let scope-creep overwhelm me on this).> > ...SCOPE CREEP!What did you call me???> > -- Jeff Dutky> > > > >


Re: Greetings From a New Member

Gordon Smith
 

Hi Jon,
You are correct Sir. General Atomics developed Nuclear Reactors in the 1950's and had a very advanced, for it's time, experimental Gas Cooled Reactor in the 60's that unfortunately did not get to commercial production. There claim to fame in the nuclear field is that they still offer and support the TRIGA Research Nuclear Reactor ( https://en.wikipedia.org/wiki/TRIGA ) that was Designed under Freeman Dyson (with Edward Teller advising). Regarding the TEK scopes being addicting, I can understand. I have always been a devotee of elegant design and the Vacuum tube based Tek scopes are just gorgeous examples of elegant design.

Regarding photos of the NLS VM's. I may be able to provide some. I have examples of the two total extremes of their voltmeters. One is from the mid 50's, vacuum tubes everything with stepper motor actuation of the Edge Lit Display (It's my second heaviest piece of test equipment behind the Tek 547). A US Air Force contract Volt meter. And the other is a Model 2900 from the late 60's with discrete semiconductors for everything. Fun Pieces of equipment.

Thank You for the Bandwidth,

Gordon


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 03:57 AM, Tom Lee wrote:


My favorite tool for annotating PDFs (because it’s free) is Foxit PDF
Reader. The comment feature allows text input as well as freehand drawing with
a pencil tool.
I remember using Foxit PDF Reader and being quite happy with it. These days, my standard is PDF-XChange Editor Plus for the extra features, like batch processing, with the PDF-Tools add-on. I think that PDF-XChange Editor (non-Plus) is still free.

Raymond


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

toby@...
 

On 2020-12-08 9:01 p.m., Jeff Dutky wrote:
Dave Paterson wrote:

I'd say this deserves a new topic under calibration, but I wouldn't want to loose the connection to all this good info in this one.
I intend to post my write up of this discussion, along with a summary of the 475/475A calibration procedure using the suggested replacement equipment, under a new topic (Scope Calibration Using Home Brew Equipment? I'm open to suggestions). I was actually going to ask for your input on the service manual calibration procedures, so that we could extend the document to include more than just the 475/475A (and maybe some of the 2200 scopes, but I'd rather not let scope-creep overwhelm me on this).

...

SCOPE CREEP!

What did you call me???



-- Jeff Dutky





Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

Tom Lee
 

My favorite tool for annotating PDFs (because it’s free) is Foxit PDF Reader. The comment feature allows text input as well as freehand drawing with a pencil tool.

I’m sure that there are many others out there, but this is what I’ve been using for ages. It’s much less bulky than Acrobat.

—Cheers
Tom

Sent from my iThing, so please forgive typos and brevity.

On Dec 8, 2020, at 6:54 PM, Raymond Domp Frank <hewpatek@gmail.com> wrote:

On Wed, Dec 9, 2020 at 03:42 AM, Dave Peterson wrote:


I'm using OneNote on my workbench PC to document my progress as I go. It's a
way to track what's done to this scope without penciling it directly in the
SM. And a way for me to organize the procedures for myself.
You may consider using a pdf version of the SM and use a PDF-reader that allows text markup. Combined with text searching ability you'll have a very powerful tool!

Raymond





Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 03:42 AM, Dave Peterson wrote:


I'm using OneNote on my workbench PC to document my progress as I go. It's a
way to track what's done to this scope without penciling it directly in the
SM. And a way for me to organize the procedures for myself.
You may consider using a pdf version of the SM and use a PDF-reader that allows text markup. Combined with text searching ability you'll have a very powerful tool!

Raymond


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

Dave Peterson
 

I'm using OneNote on my workbench PC to document my progress as I go. It's a way to track what's done to this scope without penciling it directly in the SM. And a way for me to organize the procedures for myself.

The SM calibration is meant for folks who know what they're doing. I'm familiar with this as this is how it was in the Army. Know the process, but follow the manual as a guide and reminder. Like the tear-down guide I want to produce, I feel I can use my first timer's experience to perhaps clarify the cal procedure for others like myself.

So I have some overly verbose notes that I'd like to parse down into something more organized and concise. I'm happy to share. I am realizing that my "calibration" will be incomplete for some time. There's clearly some tooling that needs to be done before a true calibration can be had. The question is can a useful tuning guide be parsed out of the full calibration? I don't know yet what the consequences of not doing some of the cal is. Can the vertical channels and time sweep be adjusted well enough with basic tools to be serviceable? Can quality be gained incrementally? For myself, I think probably so. But I can't be sure yet. I don't have the full understanding and experience yet. Learning it and sharing IS the hobby.

I'm taking note of everyone's inputs. It's all gold! Thanks!
Dave

On Tuesday, December 8, 2020, 06:01:29 PM PST, Jeff Dutky <jeff.dutky@gmail.com> wrote:

Dave Paterson wrote:

I'd say this deserves a new topic under calibration, but I wouldn't want to loose the connection to all this good info in this one.
I intend to post my write up of this discussion, along with a summary of the 475/475A calibration procedure using the suggested replacement equipment, under a new topic (Scope Calibration Using Home Brew Equipment? I'm open to suggestions). I was actually going to ask for your input on the service manual calibration procedures, so that we could extend the document to include more than just the 475/475A (and maybe some of the 2200 scopes, but I'd rather not let scope-creep overwhelm me on this).

Concerning the "flaw" in your personality: there may well be tasks for which it is sufficient to blindly follow instructions, but my experience on the operations staff for a large government data system is that those tasks are few and far between. In most cases the person performing the task really does need to understand why they are doing each step, and, to a practical extent, what the effects of each step are likely to be. People who just follow the recipe without understanding the whys and hows tend to make a terrible hash of things without noticing, and it falls to those of us who do understand to clean up the messes.

The normalizers appear to be an in-line device that you attach directly to the BNC (or whatever) connector on the subject instrument, and has a second BNC connector to which you can presumably attach a signal source. Here is an eBay search showing some of the available parts: https://www.ebay.com/sch/i.html?_nkw=tektronix+normalizer (ignore the Normalizer Head and the Signal Normalizer Plug-In, I think)

-- Jeff Dutky


Re: Yet another use for a curve tracer

Sean Turner
 

Dennis,

This is most definitely true. I got me a very nice 577D1 on the same trip I picked up my 519 on, and suffice to say, I am discovering something new it can do every day. Now to collect all the handy test fixtures Tek made...

Sean

On Tue, Dec 8, 2020 at 10:53 AM, Dennis Tillman W7pF wrote:


Hi Ed,
Curve tracers are very versatile instruments and the only real limitation they
have is the person at the controls.
Nearly everyone I know who owns a curve tracer thinks they are only good for
checking transistors.

What you did was think outside the box, and as you said in the subject, you
found another use for a curve tracer.
I hadn't thought of using it to test lamp dimmers myself so I learned
something new.
But I have used it to test capacitors, inductors, transformers, pots, SCRs,
TRIACs, DIACs, MOVs, OpAmps, Voltage Regulators ICs, Spectrum Tubes, light
bulbs, etc.
Anything with two or three leads is fair game for a curve tracer.

Anyone who owns a curve tracer is extremely fortunate. You can learn a great
deal about how electronic parts of all kinds respond when you connect them to
a curve tracer.

Thanks for sharing your clever idea.

Dennis Tillman W7pF


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 02:38 AM, Harvey White wrote:


Many rise time measurements can be done with a 1 Khz wave, with the frequency
only determining the overall brightness of the trace.
This to the extent that a repetition frequency of 1 kHz is too low to be used for adjusting a 465's, 475's etc. rise time because the trace will be invisible.

Raymond


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 02:38 AM, Harvey White wrote:


All the other waveforms are specified to amplitude (IIRC) and *not* risetime.
That is correct. Two notes:

- The PG506 used to contain low-pass filters on its amplitude-adjustment outputs, except for the highest amplitudes. This was to prevent internally generated noise to be visisble at low set voltages. The relays used to switch the filters tended to die, so in many units, the filters were skipped by moving the output coaxial cable (with Peltola connectors) from the filter output to the filter input. It was just long enough to do that.

- The high-voltage output was used to drive a separate tunnel-diode fast rise time generator for adjusting some faster 'scopes. ISTR that the tunnel-diode pulse had a rise time of about 100 - 150 ps.

Raymond


Re: Historical Analog Scope Triggering Techniques

tgerbic
 

I use several vendors equipment so thought I would throw this out as an option. Some of you may be familiar with the HP 166xAS family of LAs. This is an interesting portable 32, 64, 102 or 136 channel LA with a integrated 2 channel 1Gsps scope. It has a lot of the 16500c series features, such as inverse assemblers. The LA function can trigger the scope or the scope can trigger the LA function. If you are looking for a standalone/bench integrated LA/Scope, especially one that can cross trigger, this might be the answer. They can usually be found on ebay at a reasonable price The 1661CS is the color version but they are usually quite expensive.

Back in the 80's when I used to write service manuals, I purchased a fully decked out Tek color DAS 9100. I hated giving it up but dev engineering eventually got jealous and took it away. As I remember, I could trigger a scope off that as well.

Regards


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 02:38 AM, Harvey White wrote:


As Raymond pointed out, sure enough, the procedure for vertical calibration
calls for a 3.5ns edge in the High-Frequency Compensation, step 23.
Not exactly. You need a fast-enough edge to be able to adjust the 3.5 ns edge that is the 465's ability. For that, the source (generator) of the edge needs to be very much faster than 3.5 ns or you'll see the edge that the generator is capable of, not the 'scope's rise time.

Raymond


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

Dave Paterson wrote:

I'd say this deserves a new topic under calibration, but I wouldn't want to loose the connection to all this good info in this one.
I intend to post my write up of this discussion, along with a summary of the 475/475A calibration procedure using the suggested replacement equipment, under a new topic (Scope Calibration Using Home Brew Equipment? I'm open to suggestions). I was actually going to ask for your input on the service manual calibration procedures, so that we could extend the document to include more than just the 475/475A (and maybe some of the 2200 scopes, but I'd rather not let scope-creep overwhelm me on this).

Concerning the "flaw" in your personality: there may well be tasks for which it is sufficient to blindly follow instructions, but my experience on the operations staff for a large government data system is that those tasks are few and far between. In most cases the person performing the task really does need to understand why they are doing each step, and, to a practical extent, what the effects of each step are likely to be. People who just follow the recipe without understanding the whys and hows tend to make a terrible hash of things without noticing, and it falls to those of us who do understand to clean up the messes.

The normalizers appear to be an in-line device that you attach directly to the BNC (or whatever) connector on the subject instrument, and has a second BNC connector to which you can presumably attach a signal source. Here is an eBay search showing some of the available parts: https://www.ebay.com/sch/i.html?_nkw=tektronix+normalizer (ignore the Normalizer Head and the Signal Normalizer Plug-In, I think)

-- Jeff Dutky


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 02:38 AM, Harvey White wrote:


I have to mention that in performing these sorts of procedures I find that I
suffer from the same ailment I had in the Army. It's not good enough for me to
follow the procedure. I have a personal flaw in which I need to understand
what I'm doing via the procedure. What am I doing, why, what effect previous
steps have on the current adjustments, and what effects the current
adjustments have on the next steps. I have to "grok" it. So I'm slow.
This is becoming a very long thread. I don't know if the Tek documents "ABC's of Probes" and "XYZ of Oscilloscopes" have been pointed out. There are several editions available, readily downloadable from the wen and on the TekWiki website. These are very clear introductory must-reads.

Raymond


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

 

On Wed, Dec 9, 2020 at 02:38 AM, Harvey White wrote:


Like attenuators as needed? Needed for what precisely? Waveform
characteristics? Noise?
The phrase "attenuators as needed" in the SM refers to the voltage needed to adjust the scope's input, which is set across several decades. Fixed attenuators are needed to adjust the generator's voltage to achieve the specified vertical deflection as per the adjustment description.

Raymond


Re: SUCCESS! The "sick" 475A is now the "fixed" 475A!

Harvey White
 

responses interleaved and I'll add an anecdotal tale (but true).

On 12/8/2020 6:34 PM, Dave Peterson via groups.io wrote:
I'd say this deserves a new topic under calibration, but I wouldn't want to loose the connection to all this good info in this one.

I spent some time working through the calibration procedure from the 465 manual last night. I was in the "Vertical System Calibration" section of the "Short-Form Calibration". Uhg! The depth of my ignorance is further revealed!

I have to mention that in performing these sorts of procedures I find that I suffer from the same ailment I had in the Army. It's not good enough for me to follow the procedure. I have a personal flaw in which I need to understand what I'm doing via the procedure. What am I doing, why, what effect previous steps have on the current adjustments, and what effects the current adjustments have on the next steps. I have to "grok" it. So I'm slow.
Everybody learns differently, some is kinesthetic, (you have to do it with your hands to understand it), some is auditory (hear it and it's gold), some visual (doesn't make sense until you see the picture).  Slow is not a factor.

I now understand better some of the issues Raymond raised with the idea of a cheap function generator. I do find it useful, and it's working well for what it is. But it does have it's limitations regarding verifying the specs of the 465. I'll have to keep my eye on the recommendations here, like the fast edge pulse generator. As Raymond pointed out, sure enough, the procedure for vertical calibration calls for a 3.5ns edge in the High-Frequency Compensation, step 23. And the bandwidth of the vertical input section requires a 100MHz capable signal source - who's roll off is above that. The cheap FG starts rolling off at about 10MHz.
The problem on some function generators is not the frequency.  Many rise time measurements can be done with a 1 Khz wave, with the frequency only determining the overall brightness of the trace.  The real problem is the rise time.  To measure the rise time of a scope, you need a waveform that is significantly better than the rise time to be measured, perhaps at least by a factor of 10 so that the contributions of the generator are minimized.  Most function generators don't do that.  In fact, the PG506 has two specific outputs, one with a + risetime that's specified, one with a - risetime.  All the other waveforms are specified to amplitude (IIRC) and *not* risetime.  The risetime waveforms *only* are specified for risetime, you don't care about the amplitude.

I have to say, one of my motivations behind all of this is/was my interest in building some audio amps. My daughter is learning electric guitar and I thought it'd be fun to build some for both of our entertainment. She'd learn what's going on with amps, and I'd get to practice and learn the issues and effects impacting audio amp design and build. So the two-channel sweep FG I think will work well in an audio application, and helps get me started on the scope tuning front. And a 465 is a good scope to use for it as well. Why I finally pulled the trigger on it. Oops.
As has been mentioned, the essential difference in amplifiers is how they sound, and that's subjective.  One measure of hearing is distortion.  If an amplifier sharply clips, then it introduces a lot of odd order harmonics, and the sound is perceived as "harsh".  If it softly clips (a characteristic of tube amplifiers driving transformers), then the energy in those harmonics is reduced.  It's still clipping, but it's a "softer" clipping. Different sound.  Not so much subjective (since it can be seen and measured) but it is interpreted differently.


I suspect I'll have more questions the further I go through the calibration procedure. Something that I encountered last night was mentioned by Raymond in reply to Tom: a 20pf normalizer. What is a normalizer? Why are people using a 10x probe for it? The 465 manual leaves a lot to be desired in explaining some of these things. Like attenuators as needed? Needed for what precisely? Waveform characteristics? Noise?
This one is easy.  An oscilloscope input looks like a resistor in parallel with a capacitor, both connected to ground.  At DC, all you see is the resistor.  As the frequency goes up, the capacitive reactance (looks a bit like a resistor) goes down with frequency, so there's a frequency when you see 1 meg of resistance in parallel with 1 meg of reactance, and your signal sees 500K.  Your standard oscilloscope probe is a resistor in parallel with a capacitor.  Those form a voltage divider. At DC, you see a 9 meg resistor in series with a 1 meg resistor (DC = no capacitors), and get a 10:1 division ratio.  As the frequency goes up, the loading (due to the capacitors) goes up (lower effective reactance), and you need to adjust the capacitor in the probe for the appropriate 10:1 ratio, since the capacitance predominates.

It's not as simple as that, since you have the inductance of the cable, the capacitance of the cable, and a few other things to consider.

What the normalizer does is to be a 2:1 divider with the capacitor adjusted precisely to feed a network of exactly 1 meg paralleled with a 20 pf capacitor.  In other words, exactly what the scope input is specified to be.   Put the normalizer on, adjust the scope for proper response, and the scope input is 1 meg and 20 pf.  Since that's the standard, when you adjust one probe to make it exact (for 1 meg and 20 pf), it ought to be exact for any *other* 1 meg and 20 pf input.  Just for fun, the higher frequency scopes need less capacitance, HP has a different standard capacitance, and there are scopes with 50 ohm inputs where the capacitance plays a lot less of a role in the input impedance.

Hope this helps.



I have a long wish list of test equipment queued up on Amazon. Like 50ohm cables, BNC connectors of many sorts - like T's, and 50ohm BNC terminators. Those were called for often in test setups in the Army. Do I need other values? Do cap "normalizers" come as BNC connections? How are they connected? In-line? Shunt?
Normalizers are a small box with either BNC (for newer scopes) M and F on either side, series connection between the generator and the scope, or UHF (SO-239) connectors for older equipment.

Now for the anecdote.  In my early days, I had Heathkit equipment.  A sine/square wave generator and an oscilloscope (OM-3) that likely barely hit 500 Kc (as it was then).  I put the resistors in the generator by bending the leads, and using all the leads, letting the resistors have an inch or more lead.  No problem, the generator output looked fine.

Then I got a Tektronix scope (a 513D), which had a much higher bandwidth.  The excess lead length of the resistors caused the circuits to ring, lots.  What I thought was a square wave certainly wasn't a good one.

SO what you see is completely dependent on your measuring equipment, yet you do have, somewhere in there, the concept of "what's good enough".

so with a square wave generator that's got too slow a rise time, you just simply can't adjust a fast risetime circuit.  Best to leave it alone until you have the right equipment.

Always tons to learn, regardless of where you are.  Fun, though.

Harvey

Tons to learn!
Dave





Re: Calibrating a PG506 w/o Sampling System

 

That error is almost always due to dead batteries in the two static ram chips on the timing board. The rams are plugged into a Dallas memory hold up socket and can be removed by unplugging it. The rams can be replaced by Mouser part number 511-M48Z3570PC1. Two of them should run around $30. After installing both chips, do a few power up cycles and the error should be gone.

Regards,

Tom

On 12/8/2020 5:46 PM, Rick wrote:
Oops I'm off to a great start. It's code T2325. Only off by two digits, just like the lottery.



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