|
Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope. Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up." The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing?
Thank you.
David
|
On 6/9/2019 10:25 AM, David Berlind wrote: Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.). Nice price. My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc). This I can't help with, I have neither. 2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope. There's an auto set (or should be) that tries to guess at the proper settings for a waveform, it's a place to start. I always start at the highest sweep speed (for an unknown waveform) and go down.? Put in a 100 Khz sine wave, for instance, set the sweep appropriately, then start slowing the sweep down. You'll reach a point where you duplicate the original waveform, but at a very wrong sweep speed.? Has to do with sampling and waveform reconstruction. 3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope. Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior? No real incompatibilities, except that your average X1 probe is lucky to get to a 1 Mhz bandwidth, and your average X10 probe (unless otherwise noted) is about 100 to 200 Mhz if that.? Google Tektronix probe information (or the Tek wiki) and that will give you the bandwidth.? The limitation is in the probe, not the scope. Note that the average x1/x10 is made for a 1 meg ohm input impedance scope, and the circuit sees (at DC only) 1 or 10 Megohms.? A 50 ohm probe if at X1, would need a 50 ohm input impedance at the scope, and the circuit would see 50 ohms DC.? An X10 would need the same 50 ohm input impedance, but the circuit would see 500 ohms. I say DC because at higher frequencies, the capacitive loading of the probe predominates.? Given that a 50 ohm and 1 megohm probe have the same capacitive loading, the effect of that impedance across 50 ohms is far less than across 1 meg, and the 50 ohm probe would have higher bandwidth. 50 ohm x10 probes can be successfully used on TTL and some CMOS circuits where the resistive effect predominates normally. These probes are passive, not active (no transistors inside), for active probes, that's a different discussion. 4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up." The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing? There are, but if you're not in the continental US (and perhaps even if you are), shipping may be prohibitive even if the service would be free. There are a number of performance "checks" in the manual.? Doing them as best you can will tell you if the scope needs any calibration, and will also indicate how close you are to that mythical "calibrated". Harvey Thank you.
David
|
Great pointers Harvey. Thank you and looking forward to more. In partial answer to my first question, as I pour through the two very differently format data sheets that I have (one that includes the 620A and the other includes the 620B), I suddenly noticed that the data sheet that includes the 620B also includes the 640A with some side by side comparisons of some specs. Does someone know if the 640A is identical to the 620A except for the 4 vs. 2 channels? If so, that gives me a couple of ideas on how the 620A differs from the 620B differ and on what topics the manual for the 620A might be different.
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On June 9, 2019 11:03:01 AM "Harvey White" <madyn@...> wrote: On 6/9/2019 10:25 AM, David Berlind wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.). Nice price.
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc). This I can't help with, I have neither.
2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope. There's an auto set (or should be) that tries to guess at the proper
settings for a waveform, it's a place to start.
I always start at the highest sweep speed (for an unknown waveform) and
go down. Put in a 100 Khz sine wave, for instance, set the sweep
appropriately, then start slowing the sweep down. You'll reach a point
where you duplicate the original waveform, but at a very wrong sweep
speed. Has to do with sampling and waveform reconstruction.
3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope. Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior? No real incompatibilities, except that your average X1 probe is lucky to
get to a 1 Mhz bandwidth, and your average X10 probe (unless otherwise
noted) is about 100 to 200 Mhz if that. Google Tektronix probe
information (or the Tek wiki) and that will give you the bandwidth. The
limitation is in the probe, not the scope.
Note that the average x1/x10 is made for a 1 meg ohm input impedance
scope, and the circuit sees (at DC only) 1 or 10 Megohms. A 50 ohm
probe if at X1, would need a 50 ohm input impedance at the scope, and
the circuit would see 50 ohms DC. An X10 would need the same 50 ohm
input impedance, but the circuit would see 500 ohms.
I say DC because at higher frequencies, the capacitive loading of the
probe predominates. Given that a 50 ohm and 1 megohm probe have the
same capacitive loading, the effect of that impedance across 50 ohms is
far less than across 1 meg, and the 50 ohm probe would have higher
bandwidth.
50 ohm x10 probes can be successfully used on TTL and some CMOS circuits
where the resistive effect predominates normally.
These probes are passive, not active (no transistors inside), for active
probes, that's a different discussion.
4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up." The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing? There are, but if you're not in the continental US (and perhaps even if
you are), shipping may be prohibitive even if the service would be free.
There are a number of performance "checks" in the manual. Doing them as
best you can will tell you if the scope needs any calibration, and will
also indicate how close you are to that mythical "calibrated".
Harvey
Thank you.
David
|
I don¡¯t have a lot of knowledge but two things. In the 540, 540A, 540C, etc the ¡° ¡° and ¡°A¡± speak a different HPIB language from the ¡°B¡± and ¡°C¡±. If a lab says calibration for $300 they ¡°may¡± hook it up and make sure the readings are close but not much else.
I don¡¯t know what a fully automated set could do, I do all my calibrations manually with the Tek software. The 540B takes about 5 hours to do a good job. If you were close I say bring it by and turn you loose on my software.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
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Show quoted text
On Jun 9, 2019, at 08:25, David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope. Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up." The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing?
Thank you.
David
|
Thanks Stephen. Unfortunately, I'm in Boston. Googling HPIB now.
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On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@...> wrote: I don¡¯t have a lot of knowledge but two things. In the 540, 540A, 540C, etc the ¡° ¡° and ¡°A¡± speak a different HPIB language from the ¡°B¡± and ¡°C¡±. If a lab says calibration for $300 they ¡°may¡± hook it up and make sure the readings are close but not much else.
I don¡¯t know what a fully automated set could do, I do all my calibrations manually with the Tek software. The 540B takes about 5 hours to do a good job. If you were close I say bring it by and turn you loose on my software.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope. Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up." The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing?
Thank you.
David
|
As I await all your answers, I started with page 1 of the manual this morning and am liking the functionality. Compared to my initial quick-plug-it-in see if it works the other day, things went much better. The first thing I did was a factory reset (following the manual's instructions of course). This may have fixed a few things. Working with the probe calibration signal, here's a video of what I observed after selecting some measurements for display. I'm using some100Mhz probes at 1x.
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Show quoted text
On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@...> wrote: I don¡¯t have a lot of knowledge but two things. In the 540, 540A, 540C, etc the ¡° ¡° and ¡°A¡± speak a different HPIB language from the ¡°B¡± and ¡°C¡±. If a lab says calibration for $300 they ¡°may¡± hook it up and make sure the readings are close but not much else.
I don¡¯t know what a fully automated set could do, I do all my calibrations manually with the Tek software. The 540B takes about 5 hours to do a good job. If you were close I say bring it by and turn you loose on my software.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope. Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up." The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing?
Thank you.
David
|
Very rough rule of thumb on square waves.? A "decent" square wave requires response to about 10x the fundamental frequency.? (it only has odd harmonics).? So your 1 Khz calibrator requires a decent frequency response to (gasp!) 10 Khz.
Still, the frequency compensation on most adjustable probes is decent enough when done at 1 Khz.? For other frequencies and the like, the "flat top" of the square wave will likely be insufficient.? That also varies per probe.? The P6015 high voltage probe has at least six or seven separate adjustments for frequency response and flatness.
Normally, though, what Tek did is to optimize pulse response over flatness of frequency response.
Video looks good to me.
Harvey
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On 6/9/2019 1:29 PM, David Berlind wrote: As I await all your answers, I started with page 1 of the manual this morning and am liking the functionality. Compared to my initial quick-plug-it-in see if it works the other day, things went much better. The first thing I did was a factory reset (following the manual's instructions of course). This may have fixed a few things. Working with the probe calibration signal, here's a video of what I observed after selecting some measurements for display. I'm using some100Mhz probes at 1x.
On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@...> wrote:
I don¡¯t have a lot of knowledge but two things. In the 540, 540A, 540C, etc the ¡° ¡° and ¡°A¡± speak a different HPIB language from the ¡°B¡± and ¡°C¡±. If a lab says calibration for $300 they ¡°may¡± hook it up and make sure the readings are close but not much else.
I don¡¯t know what a fully automated set could do, I do all my calibrations manually with the Tek software.? The 540B takes about 5 hours to do a good job.? If you were close I say bring it by and turn you loose on my software.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the last two years and seeing some of what the digital scopes could do (for example, maths), I had been watching my local marketplaces carefully for a good price on a digital scope in working condition. I recently picked up at TDS 620B for $85 and am now beginning the journey of getting to know it. I will be posting video of its behavior which I think may be in need of correction based on initial observations.. and I am of course looking for advice. But I may be wrong about that. I will work on eliminating other issues first (configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical Reference and printed that out. But in terms of the User Manual, I could only find a manual for the 620A (could just be bad Googling skills). So, I downloaded and printed that out. Now, I'm trying to ascertain whether the 620A manual is for the most part applicable (should have done this before killing a tree to print it I guess) or whether the 620A is different enough from the 620B that the manual doesn't apply. I've been looking for some way to compare the two side by side (I found some differently formatted data and specification sheets so apples to apples isn't perfect, but there's some overlapping data to get some jist). But I thought it would be prudent to toss the question out to this group because maybe someone will just know and can summarize key differences and how that impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get started with this scope. Configurations to try. Shortcuts. Anything that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed from the 620A documentation that that scope originally came with a 6139A probe which lead me into an exploration of probe characteristics. That probe's specs appear to match the 500Mhz capability of the scope.? Over the last two years, I haven't thought much about the probes themselves. Just been using what I acquired along the way and things seem to work. So, in the spirit of rooting out any configuration problems before needing to effect any repairs, to what extent could basic probe differences impact behavior? For example, I have some basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on my 7603. What incompatibilities could exist between these probes and the 620B such that I might get unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros take a look at the scope, I have inquired with a local calibration service as to the cost of a "tune-up."? The estimate just for calibration for was over $300 (way more than the cost of the scope). It dawned on me that one option might be to pay someone in this group to bring her up to snuff. This is for hobbyist work (repairing amps, radios, etc) so it's not like I need a certificate. Is there someone here who does that sort of thing?
Thank you.
David
|
Hey David,
I think this'll be the user manual:
.
Siggi
toggle quoted message
Show quoted text
On Sun, Jun 9, 2019 at 10:25 AM David Berlind <david@...> wrote: Hi all,
After starting my oscilloscope journey with analog scopes for the last two
years and seeing some of what the digital scopes could do (for example,
maths), I had been watching my local marketplaces carefully for a good
price on a digital scope in working condition. I recently picked up at TDS
620B for $85 and am now beginning the journey of getting to know it. I will
be posting video of its behavior which I think may be in need of correction
based on initial observations.. and I am of course looking for advice. But
I may be wrong about that. I will work on eliminating other issues first
(configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical
Reference and printed that out. But in terms of the User Manual, I could
only find a manual for the 620A (could just be bad Googling skills). So, I
downloaded and printed that out. Now, I'm trying to ascertain whether the
620A manual is for the most part applicable (should have done this before
killing a tree to print it I guess) or whether the 620A is different enough
from the 620B that the manual doesn't apply. I've been looking for some way
to compare the two side by side (I found some differently formatted data
and specification sheets so apples to apples isn't perfect, but there's
some overlapping data to get some jist). But I thought it would be prudent
to toss the question out to this group because maybe someone will just know
and can summarize key differences and how that impacts anything (usage,
probes, etc).
2. I'll take any suggestions from you pros on great ways to get started
with this scope. Configurations to try. Shortcuts. Anything that will
fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed
from the 620A documentation that that scope originally came with a 6139A
probe which lead me into an exploration of probe characteristics. That
probe's specs appear to match the 500Mhz capability of the scope. Over the
last two years, I haven't thought much about the probes themselves. Just
been using what I acquired along the way and things seem to work. So, in
the spirit of rooting out any configuration problems before needing to
effect any repairs, to what extent could basic probe differences impact
behavior? For example, I have some basic 1X/10x probes (which might not be
rated for 500Mhz) that work nicely on my 7603. What incompatibilities could
exist between these probes and the 620B such that I might get
unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros
take a look at the scope, I have inquired with a local calibration service
as to the cost of a "tune-up." The estimate just for calibration for was
over $300 (way more than the cost of the scope). It dawned on me that one
option might be to pay someone in this group to bring her up to snuff. This
is for hobbyist work (repairing amps, radios, etc) so it's not like I need
a certificate. Is there someone here who does that sort of thing?
Thank you.
David
|
On Sun, Jun 9, 2019 at 10:25 AM David Berlind <david@...> wrote: 1. I could not locate an online manual for the 620B. I found the Technical
Reference and printed that out. But in terms of the User Manual, I could
only find a manual for the 620A (could just be bad Googling skills). So, I
downloaded and printed that out. Now, I'm trying to ascertain whether the
620A manual is for the most part applicable (should have done this before
killing a tree to print it I guess) or whether the 620A is different enough
from the 620B that the manual doesn't apply.
I think a significant difference between the 600A and 600B generations is that the Bs have peak detect acquisition mode. This allows them to catch 1ns (?) peaks even at slow sweep speeds. Note that the TDS600-series scopes are CCD-based (like the 2430-2440s of old), whereas the TDS500/700-series are ADC-based. The CCD scopes don't slow down the acquisition rate as you turn on more channels, but they don't have equivalent time nor hi-res sampling modes. They also tend to have more limited record length, and I believe they have more dead time than the 500/700s. This is due to the fact that while they capture into the CCD at a very quick rate, the contents of the CCD are then digitized at a pretty leisurely rate after a trigger is detected.
|
On Sun, Jun 9, 2019 at 07:25 AM, David Berlind wrote:
3. The 620B did not come with any probes when I purchased it. I noticed from
the 620A documentation that that scope originally came with a 6139A probe
which lead me into an exploration of probe characteristics. That probe's specs
appear to match the 500Mhz capability of the scope. Over the last two years, I
haven't thought much about the probes themselves. Just been using what I
acquired along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs, to what
extent could basic probe differences impact behavior? For example, I have some
basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on
my 7603. What incompatibilities could exist between these probes and the 620B
such that I might get unexpected/inaccurate behavior?
Here are some references for those not on the FB Old Tek Scopes group, might not have seen the latest post regarding Tek probes or haven't seen these references before ( ) : I'm thinking these are older probes references so might not be pertinent though may have some utility from the info in the links: (two links might provide some details) (more of an older scope reference) I've not gotten around to verifying the "A", "B", "C" and "D" model codes... though seems from general reading there are TDS-5XX/6XX/7XX family associated capabilities detailed (I forget at the time being).
|
Thanks, that is a great deal I didn¡¯t know about the the 600¡¯s. Find out what the ground shipping is and we can talk off line. I would like to see a 600. I see a lot of 500¡¯s and would like to see what the 600 is like.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.
toggle quoted message
Show quoted text
On Jun 9, 2019, at 16:06, nonIonizing EMF <nonionizingemf@...> wrote:
On Sun, Jun 9, 2019 at 07:25 AM, David Berlind wrote:
3. The 620B did not come with any probes when I purchased it. I noticed from
the 620A documentation that that scope originally came with a 6139A probe
which lead me into an exploration of probe characteristics. That probe's specs
appear to match the 500Mhz capability of the scope. Over the last two years, I
haven't thought much about the probes themselves. Just been using what I
acquired along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs, to what
extent could basic probe differences impact behavior? For example, I have some
basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on
my 7603. What incompatibilities could exist between these probes and the 620B
such that I might get unexpected/inaccurate behavior?
Here are some references for those not on the FB Old Tek Scopes group, might not have seen the latest post regarding Tek probes or haven't seen these references before ( ) :
I'm thinking these are older probes references so might not be pertinent though may have some utility from the info in the links:
(two links might provide some details)
(more of an older scope reference)
I've not gotten around to verifying the "A", "B", "C" and "D" model codes... though seems from general reading there are TDS-5XX/6XX/7XX family associated capabilities detailed (I forget at the time being).
|
Harvey,
Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator?
In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Thanks.
toggle quoted message
Show quoted text
On Sun, Jun 9, 2019 at 5:37 PM Harvey White <madyn@...> wrote:
Very rough rule of thumb on square waves. A "decent" square wave
requires response to about 10x the fundamental frequency. (it only has
odd harmonics). So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz.
Still, the frequency compensation on most adjustable probes is decent
enough when done at 1 Khz. For other frequencies and the like, the
"flat top" of the square wave will likely be insufficient. That also
varies per probe. The P6015 high voltage probe has at least six or
seven separate adjustments for frequency response and flatness.
Normally, though, what Tek did is to optimize pulse response over
flatness of frequency response.
Video looks good to me.
Harvey
On 6/9/2019 1:29 PM, David Berlind wrote:
As I await all your answers, I started with page 1 of the manual this
morning and am liking the functionality. Compared to my initial
quick-plug-it-in see if it works the other day, things went much
better. The first thing I did was a factory reset (following the
manual's instructions of course). This may have fixed a few things.
Working with the probe calibration signal, here's a video of what I
observed after selecting some measurements for display. I'm using
some100Mhz probes at 1x.
On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@...>
wrote:
I don¡¯t have a lot of knowledge but two things. In the 540, 540A,
540C, etc the ¡° ¡° and ¡°A¡± speak a different HPIB language from the
¡°B¡± and ¡°C¡±. If a lab says calibration for $300 they ¡°may¡± hook it up
and make sure the readings are close but not much else.
I don¡¯t know what a fully automated set could do, I do all my
calibrations manually with the Tek software. The 540B takes about 5
hours to do a good job. If you were close I say bring it by and turn
you loose on my software.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the
addressee(s) named herein and may contain legally privileged and/or
proprietary information. If you are not the intended recipient, any
dissemination, distribution or copying of this e-mail and any
attachments is strictly prohibited. If you have received this e-mail
in error, please immediately notify me and permanently delete the
original and all copies and printouts of this e-mail and any
attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the
last two years and seeing some of what the digital scopes could do
(for example, maths), I had been watching my local marketplaces
carefully for a good price on a digital scope in working condition.
I recently picked up at TDS 620B for $85 and am now beginning the
journey of getting to know it. I will be posting video of its
behavior which I think may be in need of correction based on initial
observations.. and I am of course looking for advice. But I may be
wrong about that. I will work on eliminating other issues first
(configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the
Technical Reference and printed that out. But in terms of the User
Manual, I could only find a manual for the 620A (could just be bad
Googling skills). So, I downloaded and printed that out. Now, I'm
trying to ascertain whether the 620A manual is for the most part
applicable (should have done this before killing a tree to print it
I guess) or whether the 620A is different enough from the 620B that
the manual doesn't apply. I've been looking for some way to compare
the two side by side (I found some differently formatted data and
specification sheets so apples to apples isn't perfect, but there's
some overlapping data to get some jist). But I thought it would be
prudent to toss the question out to this group because maybe someone
will just know and can summarize key differences and how that
impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get
started with this scope. Configurations to try. Shortcuts. Anything
that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I
noticed from the 620A documentation that that scope originally came
with a 6139A probe which lead me into an exploration of probe
characteristics. That probe's specs appear to match the 500Mhz
capability of the scope. Over the last two years, I haven't thought
much about the probes themselves. Just been using what I acquired
along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs,
to what extent could basic probe differences impact behavior? For
example, I have some basic 1X/10x probes (which might not be rated
for 500Mhz) that work nicely on my 7603. What incompatibilities
could exist between these probes and the 620B such that I might get
unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the
pros take a look at the scope, I have inquired with a local
calibration service as to the cost of a "tune-up." The estimate
just for calibration for was over $300 (way more than the cost of
the scope). It dawned on me that one option might be to pay someone
in this group to bring her up to snuff. This is for hobbyist work
(repairing amps, radios, etc) so it's not like I need a certificate.
Is there someone here who does that sort of thing?
Thank you.
David
|
A little study of Fourier transforms would do you wonders...
A square wave, shown in the time domain, is, well, square....
you know the picture... Up, straight across, down, straight
across, up...
If you instead take a tunable receiver, with a narrow bandwidth,
and feed it the square wave, as you tune the receiver from DC up
in frequency, you will notice that there are only signals at the
fundamental frequency of the square wave, and at the odd harmonics
of the fundamental frequency. Further, you will notice that the
amplitude of the signals the receiver sees diminishes rapidly
as the harmonic number goes up: actually by 1/harmonic number, so
by the time you get to the 9th harmonic, the amplitude is 1/9'th of
the fundamental's amplitude...
If you were an experimental researcher around Fourier's time, you
would probably try lots of things, like see what happens to your
picture of a square wave when you
eliminate all of the harmonics above a certain point...say, the
9th harmonic.
You would find, that if the harmonics below the 10th were kept, the
square wave would look pretty much like a square wave. It would have
some rounding of the leading and trailing corners, and some ripple
on the tops and bottom, but it would be a pretty good square wave.
Fast forward to a modern tektronix scope with its 1KHz square wave
scope probe calibrator signal.
If you display this signal on any scope that has a bandwidth of 10KHz
or more, it will look very much like a square wave... just as experimenters
around Fourier's time would have predicted.
When Harvey wrote "So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz"... he was indicating that the scope's square
wave calibration signal isn't much of a stress test for any modern scope,
as it could be displayed adequately on a scope with only 10KHz bandwidth.
-Chuck Harris
David Berlind wrote:
toggle quoted message
Show quoted text
Harvey,
Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator?
In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Thanks.
|
On Mon, Jun 10, 2019 at 10:37 AM David Berlind <david@...> wrote: In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Note that the automatic frequency measurement is just measuring the length of the first cycle of the recorded waveform. To give it the best chance for good measurement, do your best to fill the screen with a single waveform - so higher sampling rate, higher vertical sensitivity. Then drop the noise by turning on the BW limit - here you'll be just fine with 20MHz bandwidth. This is the same as you'd want to do if you were making a manual measurement on an analog scope. There are scopes that have a built-in hardware counter, but I don't think any of the TDS scopes do.
|
On 6/10/2019 10:36 AM, David Berlind wrote: Harvey,
Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator? Nope.? There are no 10KHz probes, and I'm not sure I've ever heard of a 100 KHz probe.? My comment was that with either an X1 probe or any X10 I've ever seen, the squareness of the waveform has so few requirements, that almost any X10 probe would work. Go for a higher frequency square wave, and you'll see some differences. For a 500 Mhz scope, the best squarewave you'll see is about 50 Mhz.? Go above that, and with everything right, the squarewave will start to round due to the scope bandwidth.? Everything right means a direct connection to the scope and a 50 ohm termination (to minimize capacitance). If you have a squarewave generator, try this with a number of different scopes, and see what's going on.? Bandwidth limit your scope and see the difference.
In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Remember that there's a voltage quantization problem, you only have so many displayable levels vertically, but you also have only so many horizontal slots to divide up the waveform anyway. Depending on where the scope decides the waveform starts (and ends), some of this is pretty normal. Harvey Thanks.
On Sun, Jun 9, 2019 at 5:37 PM Harvey White <madyn@...> wrote:
Very rough rule of thumb on square waves. A "decent" square wave
requires response to about 10x the fundamental frequency. (it only has
odd harmonics). So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz.
Still, the frequency compensation on most adjustable probes is decent
enough when done at 1 Khz. For other frequencies and the like, the
"flat top" of the square wave will likely be insufficient. That also
varies per probe. The P6015 high voltage probe has at least six or
seven separate adjustments for frequency response and flatness.
Normally, though, what Tek did is to optimize pulse response over
flatness of frequency response.
Video looks good to me.
Harvey
On 6/9/2019 1:29 PM, David Berlind wrote:
As I await all your answers, I started with page 1 of the manual this
morning and am liking the functionality. Compared to my initial
quick-plug-it-in see if it works the other day, things went much
better. The first thing I did was a factory reset (following the
manual's instructions of course). This may have fixed a few things.
Working with the probe calibration signal, here's a video of what I
observed after selecting some measurements for display. I'm using
some100Mhz probes at 1x.
On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@...>
wrote:
I don¡¯t have a lot of knowledge but two things. In the 540, 540A,
540C, etc the ¡° ¡° and ¡°A¡± speak a different HPIB language from the
¡°B¡± and ¡°C¡±. If a lab says calibration for $300 they ¡°may¡± hook it up
and make sure the readings are close but not much else.
I don¡¯t know what a fully automated set could do, I do all my
calibrations manually with the Tek software. The 540B takes about 5
hours to do a good job. If you were close I say bring it by and turn
you loose on my software.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the
addressee(s) named herein and may contain legally privileged and/or
proprietary information. If you are not the intended recipient, any
dissemination, distribution or copying of this e-mail and any
attachments is strictly prohibited. If you have received this e-mail
in error, please immediately notify me and permanently delete the
original and all copies and printouts of this e-mail and any
attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the
last two years and seeing some of what the digital scopes could do
(for example, maths), I had been watching my local marketplaces
carefully for a good price on a digital scope in working condition.
I recently picked up at TDS 620B for $85 and am now beginning the
journey of getting to know it. I will be posting video of its
behavior which I think may be in need of correction based on initial
observations.. and I am of course looking for advice. But I may be
wrong about that. I will work on eliminating other issues first
(configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the
Technical Reference and printed that out. But in terms of the User
Manual, I could only find a manual for the 620A (could just be bad
Googling skills). So, I downloaded and printed that out. Now, I'm
trying to ascertain whether the 620A manual is for the most part
applicable (should have done this before killing a tree to print it
I guess) or whether the 620A is different enough from the 620B that
the manual doesn't apply. I've been looking for some way to compare
the two side by side (I found some differently formatted data and
specification sheets so apples to apples isn't perfect, but there's
some overlapping data to get some jist). But I thought it would be
prudent to toss the question out to this group because maybe someone
will just know and can summarize key differences and how that
impacts anything (usage, probes, etc).
2. I'll take any suggestions from you pros on great ways to get
started with this scope. Configurations to try. Shortcuts. Anything
that will fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I
noticed from the 620A documentation that that scope originally came
with a 6139A probe which lead me into an exploration of probe
characteristics. That probe's specs appear to match the 500Mhz
capability of the scope. Over the last two years, I haven't thought
much about the probes themselves. Just been using what I acquired
along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs,
to what extent could basic probe differences impact behavior? For
example, I have some basic 1X/10x probes (which might not be rated
for 500Mhz) that work nicely on my 7603. What incompatibilities
could exist between these probes and the 620B such that I might get
unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the
pros take a look at the scope, I have inquired with a local
calibration service as to the cost of a "tune-up." The estimate
just for calibration for was over $300 (way more than the cost of
the scope). It dawned on me that one option might be to pay someone
in this group to bring her up to snuff. This is for hobbyist work
(repairing amps, radios, etc) so it's not like I need a certificate.
Is there someone here who does that sort of thing?
Thank you.
David
|
thank you Chuck for that explanation. I have A LOT of experiments to
conduct based on the responses here. All in due time. I realize that the 1
Khz calibration signal ain't much to speak of in terms of stress testing a
scope. But for me, at the very least, it demonstrates that something isn't
wildly wrong or dead in the scope using 1 Khz as the starting point. Plus,
since my primary application right now is audio amplifier repair.... a 1
Khz signal is typically the test signal I use anyway. I've got some radios
coming up soon though. We'll see!
toggle quoted message
Show quoted text
On Mon, Jun 10, 2019 at 11:09 AM Chuck Harris <cfharris@...> wrote: A little study of Fourier transforms would do you wonders...
A square wave, shown in the time domain, is, well, square....
you know the picture... Up, straight across, down, straight
across, up...
If you instead take a tunable receiver, with a narrow bandwidth,
and feed it the square wave, as you tune the receiver from DC up
in frequency, you will notice that there are only signals at the
fundamental frequency of the square wave, and at the odd harmonics
of the fundamental frequency. Further, you will notice that the
amplitude of the signals the receiver sees diminishes rapidly
as the harmonic number goes up: actually by 1/harmonic number, so
by the time you get to the 9th harmonic, the amplitude is 1/9'th of
the fundamental's amplitude...
If you were an experimental researcher around Fourier's time, you
would probably try lots of things, like see what happens to your
picture of a square wave when you
eliminate all of the harmonics above a certain point...say, the
9th harmonic.
You would find, that if the harmonics below the 10th were kept, the
square wave would look pretty much like a square wave. It would have
some rounding of the leading and trailing corners, and some ripple
on the tops and bottom, but it would be a pretty good square wave.
Fast forward to a modern tektronix scope with its 1KHz square wave
scope probe calibrator signal.
If you display this signal on any scope that has a bandwidth of 10KHz
or more, it will look very much like a square wave... just as experimenters
around Fourier's time would have predicted.
When Harvey wrote "So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz"... he was indicating that the scope's square
wave calibration signal isn't much of a stress test for any modern scope,
as it could be displayed adequately on a scope with only 10KHz bandwidth.
-Chuck Harris
David Berlind wrote:
Harvey,
Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator?
In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Thanks.
|
thanks Siggi for that advice.. I'll be doing exactly that. I guess I'll be
exploring the manuals .. I'm assuming that in addition to adjusting the
frequency down to 20Mhz, I can also adjust the sample rate? (from the TDS
620's 2GS/s default rate). I'll have to look that up in the manual.
toggle quoted message
Show quoted text
On Mon, Jun 10, 2019 at 11:14 AM Siggi <siggi@...> wrote: On Mon, Jun 10, 2019 at 10:37 AM David Berlind <david@...> wrote:
In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Note that the automatic frequency measurement is just measuring the length
of the first cycle of the recorded waveform. To give it the best chance for
good measurement, do your best to fill the screen with a single waveform -
so higher sampling rate, higher vertical sensitivity. Then drop the noise
by turning on the BW limit - here you'll be just fine with 20MHz bandwidth.
This is the same as you'd want to do if you were making a manual
measurement on an analog scope.
There are scopes that have a built-in hardware counter, but I don't think
any of the TDS scopes do.
|
Siggi, thanks for the link to the correct user manual. Looks like I will
have to kill another tree to print that one out.. (or maybe I'll just print
on the back side of the other manual).
toggle quoted message
Show quoted text
On Sun, Jun 9, 2019 at 5:43 PM Siggi <siggi@...> wrote: Hey David,
I think this'll be the user manual:
.
Siggi
On Sun, Jun 9, 2019 at 10:25 AM David Berlind <david@...> wrote:
Hi all,
After starting my oscilloscope journey with analog scopes for the last two
years and seeing some of what the digital scopes could do (for example,
maths), I had been watching my local marketplaces carefully for a good
price on a digital scope in working condition. I recently picked up at TDS
620B for $85 and am now beginning the journey of getting to know it. I will
be posting video of its behavior which I think may be in need of correction
based on initial observations.. and I am of course looking for advice. But
I may be wrong about that. I will work on eliminating other issues first
(configuration, line noise, etc.).
My first inquiry involves four questions:
1. I could not locate an online manual for the 620B. I found the Technical
Reference and printed that out. But in terms of the User Manual, I could
only find a manual for the 620A (could just be bad Googling skills). So, I
downloaded and printed that out. Now, I'm trying to ascertain whether the
620A manual is for the most part applicable (should have done this before
killing a tree to print it I guess) or whether the 620A is different enough
from the 620B that the manual doesn't apply. I've been looking for some way
to compare the two side by side (I found some differently formatted data
and specification sheets so apples to apples isn't perfect, but there's
some overlapping data to get some jist). But I thought it would be prudent
to toss the question out to this group because maybe someone will just know
and can summarize key differences and how that impacts anything (usage,
probes, etc).
2. I'll take any suggestions from you pros on great ways to get started
with this scope. Configurations to try. Shortcuts. Anything that will
fast-track my introduction to expert operation of the scope.
3. The 620B did not come with any probes when I purchased it. I noticed
from the 620A documentation that that scope originally came with a 6139A
probe which lead me into an exploration of probe characteristics. That
probe's specs appear to match the 500Mhz capability of the scope. Over the
last two years, I haven't thought much about the probes themselves. Just
been using what I acquired along the way and things seem to work. So, in
the spirit of rooting out any configuration problems before needing to
effect any repairs, to what extent could basic probe differences impact
behavior? For example, I have some basic 1X/10x probes (which might not be
rated for 500Mhz) that work nicely on my 7603. What incompatibilities could
exist between these probes and the 620B such that I might get
unexpected/inaccurate behavior?
4. Wondering whether it might be best and faster just to have the pros
take a look at the scope, I have inquired with a local calibration service
as to the cost of a "tune-up." The estimate just for calibration for was
over $300 (way more than the cost of the scope). It dawned on me that one
option might be to pay someone in this group to bring her up to snuff. This
is for hobbyist work (repairing amps, radios, etc) so it's not like I need
a certificate. Is there someone here who does that sort of thing?
Thank you.
David
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Fear not, tree farmers will plant more.
I always find it funny that folks lament the use of a tree,
that was planted by a farmer as a crop, destined for use as
paper or lumber, but never say a peep about the use of corn,
or wheat, or tomatoes...
For the sake of our children, please, please, save the corn!
...Was a cry heard by no one...
-Chuck Harris - who apologizes in advance for this off topic comment...
David Berlind wrote:
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Siggi, thanks for the link to the correct user manual. Looks like I will
have to kill another tree to print that one out.. (or maybe I'll just print
on the back side of the other manual).
On Sun, Jun 9, 2019 at 5:43 PM Siggi <siggi@...> wrote:
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Thanks Chuck I got a good laugh. You are right about the planting. Imagine a bare field, they plant heavily and then thin at 3 or 4 years with a clear cut at 7 or 8 then it sits over winter and they start all over. Or at least that¡¯s how the folks around us in middle Alabama did it. They had some kind of very fast growing pine. Our house was only 8 years old and the pines planted down the driveway and around the house averaging 20¡± diameter and 60 feet tall. Nice for antennas but a bit scary in a storm.
Regards,
Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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On Jun 11, 2019, at 11:24, Chuck Harris <cfharris@...> wrote:
Fear not, tree farmers will plant more.
I always find it funny that folks lament the use of a tree,
that was planted by a farmer as a crop, destined for use as
paper or lumber, but never say a peep about the use of corn,
or wheat, or tomatoes...
For the sake of our children, please, please, save the corn!
...Was a cry heard by no one...
-Chuck Harris - who apologizes in advance for this off topic comment...
David Berlind wrote:
Siggi, thanks for the link to the correct user manual. Looks like I will
have to kill another tree to print that one out.. (or maybe I'll just print
on the back side of the other manual).
On Sun, Jun 9, 2019 at 5:43 PM Siggi <siggi@...> wrote:
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