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Re: P6131, T-coils and other probe stuff
Hi Mark,
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Very nice to see you here! Your review article on sampling scopes is a true classic. I blame and thank you for the happy hours I've spent trying to chase down and then read, all the references you cite. :) I can't imagine the hours you spent amassing all of that information. Simply amazing. Gabor is a dear friend, one of the last remaining links to that earlier generation, a rarity who knows that "Bartlett bisection" isn't a medical procedure. Cheers Tom Sent from an iThing, so please forgive the typos and brevity On Jan 31, 2021, at 16:29, "Mark Kahrs" <mark.kahrs@...> wrote:
I can't resist commenting about: |
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Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
On Mon, Feb 1, 2021 at 01:02 AM, Ed Breya wrote:
Sure, important and interesting. Is there a special relevance to the point I was trying to make? AFAIK, the architecture and hardware are the same across the whole family, incl. the TDS3064 600 MHz version. Any suggestion re. how to find out? Basic resolution for these 'scopes is 9 bits. Max. RT sample rate is 5 GSa/s. Raymond |
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Re: P6131, T-coils and other probe stuff
I can't resist commenting about:
"If there is a network theorist left on your faculty (very rare these days)," In fact, it appears that circuit theory classes have nearly vanished. One of the few I know of is taught by none other than Gabor Temes: I find that some of the old classiques, such as Van Valkenburg or Kuo are truly edifying, for example, conversion from one 2-port form to another. Great stuff, highly recommended, , etc. Once you've seen transfer matrices (ABCD), you'll never look at circuit analysis the same way again. I'll stop before I wax even more ecstatically. On Tue, Jan 19, 2021 at 5:19 PM Dennis Tillman W7pF <dennis@...> wrote: When it is safe come and stay with us as our guest. We have a large house |
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Re: 7104 readout issue
Chuck Harris
Hi Sean,
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I remember now. My 7104 spends most of its time, all dressed up, with no place to go... So, it is not one of the scopes that I am most familiar with. If you look on the front panel, you will see an outlined area that has two intensity pots (A and B), a READOUT intensity pot, and two push buttons for the readout. The one button is marked +GATE or OFF, and sets the readout to be on at the end of the GATE signal, or off. The other push button is marked "MAN", which causes the readout to be on always. Something there is probably in the wrong position, or misbehaving. Also, I keep my plugins off of AUTO on my 7104. Because of the MCP's limited life, you do not want to be wasting it with continuous readout display, or baseline display. I keep my readout in "GATE" mode, so it is off if the sweep isn't being triggered. Typically, I also keep the A and B intensity turned off when the scope is off, to avoid intensity flair during turn on. -Chuck Harris [email protected] wrote: Chuck, |
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Re: 7104 readout issue
Chuck,
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Looks like mine has a more modern readout board, that contains no switch. It has a large socketed ROM where the switch would be in an older style readout system...the plot thickens... Sean On Sun, Jan 31, 2021 at 01:30 PM, Chuck Harris wrote:
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Re: Tek 4041 GPIB Controller
After the 4041 console has changed to the COMM0: serial port on the back of the 4041, you then use a terminal emulator program on your PC and a USB to RS-232 serial adapter to send programs to your 4041, and view the console on your terminal emulator. I also found a free terminal emulator for windows called Tera Term that is simple to use and it includes both VT and Tektronix terminal emulation. I have been using that program today with my 4041, and it works with EZ-TEST Generator with a couple of quirks. You need to modify the Tera Term properties following these instructions to be able to resize the Tera Term Tek window to match the size of the text so the EZ-Test menus look right: I have Tera Term screenshots running EZ-TEST in my vcfed thread: |
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Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
On Mon, Feb 1, 2021 at 12:05 AM, Bob Albert wrote:
I realize "step response" is the term commonly used. During adjustment/calibration, step response is made to follow the applied electrical voltage step as accurately as possible. Some overshoot is commonly accepted. Raymond |
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Re: 7104 readout issue
Chuck,
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Good call; I should open it up and take a look. I'm not sure where the readout board even is on a 7104...the internal layout is *vastly* different compared to the 7904(a)! Sean On Sun, Jan 31, 2021 at 01:30 PM, Chuck Harris wrote:
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Re: Tek 4041 GPIB Controller
I think I have a solution to the 4041 tape issues - I call it my 4041 Console Commander :) My Console Commander is a tiny Arduino module connected to and powered by the 4041 keyboard connector with inexpensive Dupont jumper cables. You simply turn on your 4041 and after it finishes self test - press the button on the Arduino and the Arduino sends to commands to the 4041 at 4800 N82: Here is a link to a photo of my Console Commander prototype: More details in my 4041 thread at vcfed.org: |
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Re: User Experience of Sampling Scopes
Another gotcha (that is really really expensive) are the 50 ohm female loads that came in 3.5mm cal kits made by HP. They contain super tiny "fingers" inside that help with the match. One flinch while mating that results in accidentally spinning the female connector will ruin these instantly.
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btw, I *highly* recommend investing in a set of connector gauges for SMA and up. I have a set of 3.5mm gauges in my VNA cal kit, and I also have a set of SMA gauges (these are 4 gauges since you also have two gauges for the dialectric). Sean On Sun, Jan 31, 2021 at 02:07 PM, Tom Lee wrote:
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Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
Bob Albert
What do you mean, adjusting the step behavior?
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On Sunday, January 31, 2021, 02:51:21 PM PST, Raymond Domp Frank <hewpatek@...> wrote:
Inspired by recent postings in this group, I've decided to describe my experience with a TDS3054 and a TDS3054B. These 'scopes have a published bandwidth of 500 MHz on all channels. The TDS3000-series Service Manual (071-0382-01) on page 1-3 mentions a *calculated* rise time of 700 ps. This complies with BW = 350/tr (BW in MHz, tr in ns). 350 is the accepted number for analog 'scopes (Gaussian fall-off). Apparently, Tek didn't want to use the larger (400 - 450) value that makes sense for digital 'scopes with their much steeper fall-off. I measured both TDS 'scopes to indeed have about 700 ps rise time on all four channels, with only a few percent overshoot, in line with the rise time as per the specifications (although mentioned there as calculated). Two interesting things: - Both TDS 'scopes have their -3 dB points clearly above 600 MHz on all four channels! If this applies to "all" samples of this model, it indicates that 400 - 420 would be more applicable than 350 but Tek decided in their sales documentation to do as if the number 350 that everybody knows from the analog age would apply, calculating BW from tr. The assumption "Nobody is interested in BW, rise time is what counts" wouldn't be surprising in these digital times. - Tek sold a TDS3064 having a BW spec. of *600 MHz* with V/div. settings that nicely match my checking results for the two TDS3054's! AFAIK, checking and (automatically) calibrating frequency behavior in these 'scopes is done by adjusting the step behavior. Any comments? Raymond |
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Re: User Experience of Sampling Scopes
On Sat, Jan 30, 2021 at 07:07 PM, Jeff Dutky wrote:
You can't appreciate them, unless you appreciate the math. I think they were first used in pulsed RADAR ... but the 500 series based samplers were used in early Cold War Nuclear research. Reg is the geophysics guy... and they were used in geophysics too. |
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Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
Inspired by recent postings in this group, I've decided to describe my experience with a TDS3054 and a TDS3054B.
These 'scopes have a published bandwidth of 500 MHz on all channels. The TDS3000-series Service Manual (071-0382-01) on page 1-3 mentions a *calculated* rise time of 700 ps. This complies with BW = 350/tr (BW in MHz, tr in ns). 350 is the accepted number for analog 'scopes (Gaussian fall-off). Apparently, Tek didn't want to use the larger (400 - 450) value that makes sense for digital 'scopes with their much steeper fall-off. I measured both TDS 'scopes to indeed have about 700 ps rise time on all four channels, with only a few percent overshoot, in line with the rise time as per the specifications (although mentioned there as calculated). Two interesting things: - Both TDS 'scopes have their -3 dB points clearly above 600 MHz on all four channels! If this applies to "all" samples of this model, it indicates that 400 - 420 would be more applicable than 350 but Tek decided in their sales documentation to do as if the number 350 that everybody knows from the analog age would apply, calculating BW from tr. The assumption "Nobody is interested in BW, rise time is what counts" wouldn't be surprising in these digital times. - Tek sold a TDS3064 having a BW spec. of *600 MHz* with V/div. settings that nicely match my checking results for the two TDS3054's! AFAIK, checking and (automatically) calibrating frequency behavior in these 'scopes is done by adjusting the step behavior. Any comments? Raymond |
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Re: User Experience of Sampling Scopes
On Sat, Jan 30, 2021 at 01:18 PM, Miguel Work wrote:
Yes.. that's it... you can't forget that screen. Thanks for the video. I've got 7S11 and 7T11 in a 7603, and some sampling heads...but, I don't know where... and I haven't fired it up for a few years. |
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Re: bandwidth
Typo: ¡°SG503¡± should be SG504. The former does the sensing inside the instrument and obligates you to buy an expensive cable to keep leveling quality all the way to the end of the cable. The SG504 puts the sensor at the point of delivery.
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Sent from my iThing, so please forgive typos and brevity. On Jan 31, 2021, at 2:37 PM, Tom Lee <tomlee@...> wrote: |
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Re: bandwidth
Bob Albert
Thanks Jon but I am not looking for accurate calibration.? After reading the manual a few times I see there are three adjustments for each channel.? So when I feel motivated I will look for them and try a tiny tweak to see what happens.
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What I basocally want is for the -3 dB frequency to be above 300 MHz.? With three adjustments per channel I can see how I could get into a lot of trouble.? I don't want certified calibration so maybe I can boost the -3 dB frequency a little.? It's not terribly important. Bob On Sunday, January 31, 2021, 02:23:28 PM PST, Jean-Paul <jonpaul@...> wrote:
Rebonjour, further musings..... 1/ We use? a leveled sine cal generator, eg Tek SG503,SG504 etc or HP 8640B to check BW. 2/ less is more... Eliminate cables if possible, the excellent Leo Bodnar 40 ps pulser has a BNC female to connect directly? to a 50ohm scope input. 3/ For 1 M ohm input scopes, Feedthru terms are not perfect, we have? some old ones or Chinese clone junk that are NOT good above 100 MHz, we recommend the Tektronix BNC 50 ohm feedthru, or the Mini-Circuits 4/ Tweaking transient response is an art not a science, use care, patience and compromise. 5/ like any amplifier, a scope vertical amp can have non-linearity.? The? response ( transients or BW) may change depending upon the trace positon on the screen. Enjoy, and happy tweaking! Amenities et cordialement, Jon |
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Re: bandwidth
Jean-Paul,
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He has said explicitly that he used an HP8657B generator. It is a leveled instrument. He made measurements on several scopes. Those measurements made sense. I think it is safe to assume that he made the measurements correctly. Whatever errors he might have as a result of cable type, etc. must be small. And in any case, they were small enough to measure a 600MHz bandwidth. It is hard to contrive a scenario where he has an error that shows up only at 275MHz for that one scope, while all others look good. Help to solve his bandwidth deficit should focus on the scope that uniquely fell short of specification, not on fixturing details, nor on the type of generator used. The leveling loop in that HP sig gen is as good as it gets for a generator that controls level at its output port. The only difference between it and the 503 is that the latter senses level at point of delivery, so the cabling matters less. Again, he¡¯s already successfully measured a 600MHz bandwidth for another scope using the same setup, so the probability that he has a leveling problem is small enough to look elsewhere. Tom Sent from my iThing, so please forgive typos and brevity. On Jan 31, 2021, at 2:23 PM, Jean-Paul <jonpaul@...> wrote: |
Raymond Domp Frank