Date   

Re: TEK 7603 REPAIR

 

Thanks Jon,
Not to worry! The procedure is 1. take out board; 2. paint affected parts individually with small brush or toothbrush; 3. allow time to change oxide to acetate or phosphate etc.; 4. wash board in (distilled) water; 5. spray with methanol to remove any water, 6. allow to dry. Avoiding potentiometers: but most are sealed anyway.
Regards


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

Dave Peterson
 

I didn't know scope rot was contagious. My parts scope just died in front of me. "Live damn you!"

That's what I get for saying the fun is in fixing 'em.

Dave


Re: Tektronix 317

Bob Albert
 

On Tuesday, December 22, 2020, 12:38:39 PM PST, Bob Albert via groups.io <bob91343=yahoo.com@groups.io> wrote:

It's called a scope evaluation board and is about 30 years old.  Most of it is a battery holder.  There is a number T-1449 on it and has 3 ICs.
Bob
    On Tuesday, December 22, 2020, 12:21:48 PM PST, <brockkoren@gmail.com> wrote:

oh they won't allow that email, maybe bkoren@gamma-sci.com


Re: Tektronix 317

Bob Albert
 

It's called a scope evaluation board and is about 30 years old.  Most of it is a battery holder.  There is a number T-1449 on it and has 3 ICs.
Bob

On Tuesday, December 22, 2020, 12:21:48 PM PST, <brockkoren@gmail.com> wrote:

oh they won't allow that email, maybe bkoren@gamma-sci.com


Tek 565 3A6 3A75 FS on eBay in Germany - no affiliation

magnustoelle
 

Good Day my fellow Tektronix Enthusiasts,

there is a Tektronix type 565 oscilloscope with the above plug-ins for sales with no reserve on eBay.

https://www.ebay.de/itm/TEKTRONIX-565-Dual-Beam-Oscilloscope-mit-3A6-und-3A75/203219688080

I have no affiliation with the seller.

Have a Merry Christmas and a fine holiday season, all!

Cheers,

Magnus


Re: Tektronix 317

 

oh they won't allow that email, maybe bkoren@gamma-sci.com


Re: Thoughts About Modern Tek Scopes

stevenhorii
 

Just a quick note on Siglent stuff. I bought a Siglent signal generator - a
2042X. It has all the standard waveforms plus arbitrary waveform
capability. It has a touch screen so you could actually just draw a
waveform on it. It also has USB and Ethernet connectivity so you can load
waveforms to it. Is it as good as the high-end stuff from HP/Agilent,
likely not. But it works and does what I need it to do.

I’m just a user of it. I have no financial conflict with Siglent or their
US distributors.

Steve H.

On Tue, Dec 22, 2020 at 13:45 Jeff Dutky <jeff.dutky@gmail.com> wrote:

Raymond, David, and amirb,

You guys have really saved me from an unnecessary eBay acquisition (and
justified my original plan to get a modern Siglent scope). It looks like I
could pick up a TDS3054 for a bit less than a new Siglent, but I'd still
need probes, and the Siglents come with a bunch of options enabled for
"free".

I had no realized that the 80s era DSOs had been using sampling
techniques. I had been thinking of getting a 11400 scope, just to have a
scope on the bench that could technically do 1GHz, and to have a sampling
oscilloscope (which I understand are an endangered species), but it's such
a frivolous purchase (for me) that I have managed to resist the urge. I'm
interested in sampling scopes in a technical way, but I doubt I have a use
for such a thing (I guess I could use it to measure the actual rise time of
my Leo Bodnar fast pulse generator, but that hardly seems worth the effort
and expense). I've been following this guy (Ted Yapo) who is building an
"Open-Source Multi-GHz" sampling oscilloscope; it's both fascinating, and
would be an even more impressive addition to my bench than an 11403.

I had specifically chosen the Siglent because it has what appears to be an
excellent digital phosphor feature, better than the other cheap Chinese
DSOs I've seen reviewed on YouTube, and their price for the 200 MHz 4
channel scope is better than the other "big" Chinese manufacturers. I'm
glad that people on this group seem to think well of it, especially for a
beginner's first DSO.

Thanks for the enlightening and informative discussion.

-- Jeff Dutky






Re: Thoughts About Modern Tek Scopes

 

Raymond, David, and amirb,

You guys have really saved me from an unnecessary eBay acquisition (and justified my original plan to get a modern Siglent scope). It looks like I could pick up a TDS3054 for a bit less than a new Siglent, but I'd still need probes, and the Siglents come with a bunch of options enabled for "free".

I had no realized that the 80s era DSOs had been using sampling techniques. I had been thinking of getting a 11400 scope, just to have a scope on the bench that could technically do 1GHz, and to have a sampling oscilloscope (which I understand are an endangered species), but it's such a frivolous purchase (for me) that I have managed to resist the urge. I'm interested in sampling scopes in a technical way, but I doubt I have a use for such a thing (I guess I could use it to measure the actual rise time of my Leo Bodnar fast pulse generator, but that hardly seems worth the effort and expense). I've been following this guy (Ted Yapo) who is building an "Open-Source Multi-GHz" sampling oscilloscope; it's both fascinating, and would be an even more impressive addition to my bench than an 11403.

I had specifically chosen the Siglent because it has what appears to be an excellent digital phosphor feature, better than the other cheap Chinese DSOs I've seen reviewed on YouTube, and their price for the 200 MHz 4 channel scope is better than the other "big" Chinese manufacturers. I'm glad that people on this group seem to think well of it, especially for a beginner's first DSO.

Thanks for the enlightening and informative discussion.

-- Jeff Dutky


Re: How much does 106 of Peter Keller's CRT books weigh?

Ed (SCSKITS)
 

Dennis:

No issue here with the delay, USPS is very busy.
Let me know if you need extra for shipping.

ed


Re: TEK 7603 REPAIR

Jim Ford
 

Come to think of it, the term bias usually implies DC, but not always.   I'm thinking of the case of the old cassette tapes and how the magnetic particles were biased with an ultrasonic tone, IIRC to make them respond more linearly to the audio magnetic field, hence generating less harmonic distortion.  Not that I've played a cassette tape in many years, though.    JimSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: David Collier <dc888@tpg.com.au> Date: 12/22/20 2:16 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] TEK 7603 REPAIR Thanks JIm & Thomas,Firstly it is correct that capacitors do not pass DC; but they do pass alternating current, as in voltage doublers etc.; in this case the measured 45.5KHz from the 800V secondary of T1225 which is then rectified for the correct CRT control grid voltage.  Small 27pf capacitors for small voltage(s).Secondly, it seems the trigger selector board was indeed involved: connecting the signal output board to P339 (on this trigger board) seems to have restored all functions, though I don't understand how.Now there is plenty of brightness, and with different intensity between normal and delayed sweep.It only remains to clean a white oxidation from component leads and solder joints, either with CLR; vinegar, or Coke (sugar free of course!)Regards,David Collier.


Re: Asking for Help with Verifying Genuineness of 2465B from Ebay

TomC
 

On 12/21/2020 9:37 PM, Tom Lee wrote:
It's important to understand that the relationship between rise time and bandwidth is not as quantitatively solid as many seem to think. The oft-quoted "-3dB BW in hertz, times the 10-90% rise time in seconds = 0.35" applies to a single-pole RC system driven by a perfect (zero rise time, zero overshoot) step. For the mathophiles among you, it's (1/(2*pi))(ln(9)). If your system isn't single pole, the relationship will be different. If you're not driving it with a perfect step, the relationship will be different. Since you never have a single pole, nor a perfect step, you're actually in approximation territory in practice.
Occasionally, you will see reference made to a Gaussian response conforming to the rule of thumb above. I think I've even seen it in some Tek literature (although I may be mistaken). Strictly speaking, the constant changes from 0.35 to 1/pi, or about 0.32. But that's purely of academic interest; true Gaussian responses do not actually exist, so you're still in approximation territory.
So, you're not measuring bandwidth when you measure rise time. You are estimating it. Preserving many digits in the computation is, therefore, actually kind of silly and pointless. You may be calculating a 3-digit answer to a 1-digit question.
If you want to know the bandwidth, then measure the bandwidth.
-- Cheers,
Tom


Re: Thoughts About Modern Tek Scopes

stevenhorii
 

David,
I think you got the difference between the modern digital scopes and the
big vintage Tek scopes (or even the old Tek portables) spot on. My Tek
TDS3054 does a lot of what a 7000-series with wideband and spectrum
analyzer plug-ins does (I would not call the 3054 a spectrum analyzer
though) and some of the waveform math the 7854 did, but it does not have
the "romance" of the older Tek boxes.

The 3054 works well enough but the all-plastic case is almost toy- like.
You can't say that about a 7000-series scope full of plug-ins on its own
dedicated scope cart.

Steve H

On Tue, Dec 22, 2020, 05:28 David Collier <dc888@tpg.com.au> wrote:

Hi Jeff,
I have a 1GSa/s 2-channel 200MHz Hantek DSO5202P that was not expensive
and is the easiest to use on my workbench, because it is small and light.
No romance with it though; purely plastic and functional. My TEK 475A is
also easy to use but extends way back beyond the Hantek in length/depth.
David Collier






Re: Thoughts About Modern Tek Scopes

 

On Tue, Dec 22, 2020 at 01:37 PM, amirb wrote:


Update rate as important as it is, it is not really a "critical" spec. it is
important in catching glitches
and rare anomalies although even with a slower scope there are several ways to
catch them
That'll work by making the 'scope wait for that event. That's why powerful triggering was important. Two events in quick sequence would be difficult to catch again. Some slower 'scopes had an asynchronous glitch catching ability but you'd lose waveform info. Especially in the early DSO days, the ability to capture (rare) single-shots or low duty-cycle events was what would distinguish them from analog 'scopes, although fast analog storage 'scopes could fill the gap to some extent, as could the (1 GHz, MCP-equipped, non-storage) 7104, if *you* were fast enough!

and also having faster update rate just feels better. For me the latter, is
the main reason for having faster update rate really.
e.g. TDS3000 were not really fast scopes by any stretch of imagination, and
yet they are so popular and give such a good user experience.
The TDS3000 series had a much larger update rate than many of its competitors of the day and together with their "Digital Phosphor" behavior, there's much more to them, which is why I also still like them.


Still one of the
best digital scopes in my view
by today;s standards they must suck because of very small record length (10K)
and very slow update rate and very limited triggering capabilities but if you
work with them
you see, these limitations are hardly noticeable in normal day to day use of
scope. so a lot depends on how the overall hardware and firmware is designed
together.
I agree. It's the faster update rate (up to 3000 wfm/s I think) as opposed to a few 100 at best, together with the DPO feature and pretty powerful triggering (with the advanced triggering options put to good use) that make me grab my "TDS3054B" so often. The limited memory is hardly a problem, unless you want to observe serial data sequences.


Tek scopes even today are generally not the fastest scopes when it comes to
update rate (compared to keysight for example) but it hardly affects their
market


would be continuous and that calculation would proceed in parallel, or
even
have hardware support of some kind to keep pace with the sample rate.
Everything that I'm learning about the early DSOs and the analog storage
scopes that preceded them has been eye opening. I had always wondered how
the
early DSOs (e.g. the 2220) could get away with having a sample rate that
was a
fraction of the Nyquist frequency for the analog bandwidth, but seeing the
I think (I maybe wrong) those early DSOs used equivalent time sampling
(staggered sampling between consecutive waveforms)
Of course they did, except 'scopes like the TDS680, which like the whole TDS600 series was real-time only and with its 5 GS/s could show a one-shot 1 ns step "with ease".
The equivalent time sampling in the 2440 was very limited in that it couldn't sample over a relatively long time and assemble the result near its max.


so they were capable of having a large BW with seemingly not enough sampling
rate but in reality they did sample
the waveform >= Nyquist rate.
To avoid confusion (not yours): They didn't sample >= Nyquist frequency, instead they assembled many slow scans into one displayed picture.

However since that technique only works for
perfectly periodic signals, a lot of times you could see them go haywire when the
signal was not perfectly periodic.
I think part of the function those dreaded CCDs in 2440 was to implement this
scheme.
Not exactly: The 2440 used interleaved CCD channels to increase the limited acquisition speed of each (sequential) channel in the CCD module. Another was to assemble as you metion, with the added limitation of the 2440 that I mentioned above.


modern DSOs also have equivalent time sampling which is usually 10s or 100s
times their real time sampling. for example in TDS5000 it is 250Gs/s
but it can
And *need*
be only activated in very fast time base and
can
only used for periodic
signals.

Having said all of that, I still strongly recommend a Siglent if it is your
first DSO experience. Generally they have a fairly stable firmware
and intuitive user interface and good specs and good features as standard.
Later on however you will probably find yourself more and more attracted to
get a Tek or Agilent or Lecroy from 2000s ;-)
That would be my feeling as well...



I know nothing about the LeCroy scopes, except that they frequently appear
in
EE videos I see on YouTube. They seem to fetch real money on eBay, even
the
ones that appear to be in poor shape, so I haven't been paying them much
attention (I'm saving up for the Siglent, after all).


Re: Thoughts About Modern Tek Scopes

amirb
 

On Mon, Dec 21, 2020 at 11:55 PM, Jeff Dutky wrote:


Raymond,

I was aware that sample rate was the important factor in DSOs, but had never
heard an explanation of waveforms-per-second. That really makes the older DSOs
look like a terrible value. I had expected (naively) that sampling and storing
no, not really unless we are talking about late 80s and early 90s scopes like 2440...
Update rate as important as it is, it is not really a "critical" spec. it is important in catching glitches
and rare anomalies although even with a slower scope there are several ways to catch them while regular analog scopes could never do anyway
and also having faster update rate just feels better. For me the latter, is the main reason for having faster update rate really.
e.g. TDS3000 were not really fast scopes by any stretch of imagination, and yet
they are so popular and give such a good user experience. Still one of the best digital scopes in my view
by today;s standards they must suck because of very small record length (10K) and very slow update rate and very limited triggering capabilities but if you work with them
you see, these limitations are hardly noticeable in normal day to day use of scope. so a lot depends on how the overall hardware and firmware is designed together.
Tek scopes even today are generally not the fastest scopes when it comes to update rate (compared to keysight for example) but it hardly affects their market


would be continuous and that calculation would proceed in parallel, or even
have hardware support of some kind to keep pace with the sample rate.
Everything that I'm learning about the early DSOs and the analog storage
scopes that preceded them has been eye opening. I had always wondered how the
early DSOs (e.g. the 2220) could get away with having a sample rate that was a
fraction of the Nyquist frequency for the analog bandwidth, but seeing the
I think (I maybe wrong) those early DSOs used equivalent time sampling (staggered sampling between consecutive waveforms)
so they were capable of having a large BW with seemingly not enough sampling rate but in reality they did sample
the waveform >= Nyquist rate. However since that technique only works for perfectly periodic signals, a lot of times
you could see them go haywire when the signal was not perfectly periodic. I think part of the function those dreaded CCDs in 2440 was to implement this scheme.
modern DSOs also have equivalent time sampling which is usually 10s or 100s times their real time sampling. for example in TDS5000 it is 250Gs/s
but it can be only activated in very fast time base and only used for periodic signals.


limits of analog storage scopes put that in perspective. My instinct had been
that digital scopes from the 90s and 2000s couldn't possibly compete on both
price and performance with the modern, cheap Chinese scopes, and it sounds
like I should trust that instinct.
90s maybe not but 2000s, yes they could. The only downside would be their size/weight/fan noise
in terms of functionality and build quality and longevity and ability to calibrate, definitely I'd take any 2000s top brand scope over the chinese ones any day
with some of the cheap Chinese ones, I dont think you can find any lab to calibrate them for you. They dont even publish their calibration procedures sometimes
dont forget firmware quality and user interface is a huge deal. it's not all about specification numbers.

Having said all of that, I still strongly recommend a Siglent if it is your first DSO experience. Generally they have a fairly stable firmware
and intuitive user interface and good specs and good features as standard.
Later on however you will probably find yourself more and more attracted to get a Tek or Agilent or Lecroy from 2000s ;-)


I know nothing about the LeCroy scopes, except that they frequently appear in
EE videos I see on YouTube. They seem to fetch real money on eBay, even the
ones that appear to be in poor shape, so I haven't been paying them much
attention (I'm saving up for the Siglent, after all).


Thanks for the detailed response, it was even more informative than I had
expected.

-- Jeff Dutky


Re: Thoughts About Modern Tek Scopes

Jean-Paul
 

Jeff fine posting, been using TEK 246x/B since 1990s, and 7000 analog scopes.

In 1992 got Yokogawa digital, now use DL7440 and DL1740.

Very good interfaces and performance, both GPIB, TCPIB ethernet etc. Has utilitaires for Windows.

Tried Lecroy, very steep learning curve.

Never touched the Chinese knockoffs. Beware of lack of support or service.

Just my experience,

Jon


Re: TEK 7603 REPAIR

Jean-Paul
 

David:

Suggest to exercise and clean all controls and connectors.

Please use only iso alcohol or correct cleaners for corrosion, PCBs etc. Vinegar/coke/etc NOT recommended.

Sometimes the trimpots need cleaning or even exercising.

Suggest a complete CAL check and recal if needed.

Kind Regards,

Jon


Re: Thoughts About Modern Tek Scopes

 

Hi Jeff,
I have a 1GSa/s 2-channel 200MHz Hantek DSO5202P that was not expensive and is the easiest to use on my workbench, because it is small and light.
No romance with it though; purely plastic and functional. My TEK 475A is also easy to use but extends way back beyond the Hantek in length/depth.
David Collier


Re: TEK 7603 REPAIR

 

Thanks JIm & Thomas,
Firstly it is correct that capacitors do not pass DC; but they do pass alternating current, as in voltage doublers etc.; in this case the measured 45.5KHz from the 800V secondary of T1225 which is then rectified for the correct CRT control grid voltage. Small 27pf capacitors for small voltage(s).
Secondly, it seems the trigger selector board was indeed involved: connecting the signal output board to P339 (on this trigger board) seems to have restored all functions, though I don't understand how.
Now there is plenty of brightness, and with different intensity between normal and delayed sweep.
It only remains to clean a white oxidation from component leads and solder joints, either with CLR; vinegar, or Coke (sugar free of course!)
Regards,
David Collier.


Re: Asking for Help with Verifying Genuineness of 2465B from Ebay

Tom Gardner
 

On 22/12/20 00:46, Mr. Eric wrote:
When I take the rise time measurement, I'm using the var knob of the volts/div in order to scale the flat top and bottom of the squarewave to the 0% and 100% graticules. I then use the deltaT cursors at the intersection of the 10 and 90. I will give a thanks and shoutout to W2AEW for his videos that teach these things. I've been wondering for half my life on why I would want an uncalibrated volts/div....
With some Tek scopes, the bandwidth is noticeably reduced when the var knob is not in the "cal position".

I don't know whether that applies to the 24x5 series, but it would be worth your while checking - simply eyeball the risetime.

To get around the problem, simply have the var knob in the cal position, measure the 0% and 100% levels, calculate where the 10% and 90% occurs, and put the cursors there.


Re: Asking for Help with Verifying Genuineness of 2465B from Ebay

Tom Lee
 

Exactly! Hence the "if" clause.

You are asking the right question. Certain metrics may be attractive because of their simplicity, but one shouldn't forget what it is that we want the instrument to do.

-- 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 12/22/2020 00:16, Tom Gardner wrote:
On 22/12/20 05:37, Tom Lee wrote:
If you want to know the bandwidth, then measure the bandwidth.
And the question becomes, "why do you want to measure the bandwidth?"

Firstly a scope is a time domain instrument, and (arguably) the most important characteristic is fidelity of what is seen in the time domain. Usually that implies some variant of transient response. If there are no transients, then use a frequency domain instrument such as a spectrum analyser.

Secondly, "bandwidth" is a single number that is used as a simple proxy for the complete amplitude/phase vs frequency response.

So, work out what you measurement your system/UUT needs, and then work out to what extent the measuring instrument enables you to measure it.





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