Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
On Mon, Feb 1, 2021 at 12:05 AM, Bob Albert wrote:
What do you mean, adjusting the step behavior?
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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Chuck,
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
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On Sun, Jan 31, 2021 at 01:30 PM, Chuck Harris wrote:
Most 7000 series scopes that have readout seem to have a little
switch on the readout board that selects whether the readout
is sharing the display with the traces, or has its own time
slot after the sweep is finished.
Perhaps your switch has become intermittent?
-Chuck Harris
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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:
set driver "comm0(bau=9600,fla=bid,edit=ras):"
set console "comm0:"
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.
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
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On Sun, Jan 31, 2021 at 02:07 PM, Tom Lee wrote:
Thanks for being ¡°that guy¡±. Not being aware of the difference can cause
expensive damage, and it¡¯s one of my pet peeves.
The two connectors can mate, but the 3.5mm connector is made to much tighter
tolerances. It also has an air dielectric. Mating to a poorly made (or badly
abused) SMA can wreck a 3.5mm connector¡¯s ability to maintain low SWR all
the way out to its TEM limit. Permanent damage can be done by a single
connect-disconnect cycle.
I have sacrificial connector savers on all of my expensive gear, but
occasionally a student will remove them ¡ª against the rules ¡ª to shorten a
path or because they think the savers are introducing some artifacts. If they
then connect a random SMA cable to the gear, those students have their lab
access cards deactivated pretty quickly.
¡ª°ä³ó±ð±ð°ù²õ
Tom
Sent from my iThing, so please forgive typos and brevity.
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Re: Bandwidth vs rise time of digital 'scopes: Behavior of the TDS3054
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:
I'm curious what sorts of things you use the sampling scope to do
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:
In the video
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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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.
Sent from my iThing, so please forgive typos and brevity.
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On Jan 31, 2021, at 2:37 PM, Tom Lee <tomlee@...> wrote:
?Jean-Paul,
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:
?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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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.
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
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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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Jean-Paul,
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.
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On Jan 31, 2021, at 2:23 PM, 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: User Experience of Sampling Scopes
On Sat, Jan 30, 2021 at 12:40 PM, Jeff Dutky wrote:
Can anyone tell me if this is also true on the 11000-series scope, or do they
keep the individual, sampled dots in the final display?
Reg can tell you.
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Re: User Experience of Sampling Scopes
On Sat, Jan 30, 2021 at 09:28 AM, Dave W1BVV wrote:
W2EAW as an application engineer
Hi W1BVV, Dave: Yes, I think many Tekscopers know he works for Tektronix... and also is involved in the ARRL. I probably watched every video he ever posted (mostly directed towards Ham radio)... I can't recall any of one of them that discussed sampling oscilloscopes. Probably, I'm the one that is confused. Can you explain what sampling oscilloscope are? Best regards. Roy
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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: For Sale T5330-P2 CRT
Shalopt,
Please provide contact information so interested parties can contact you OFF-LIST.
Dennis Tillman W7pF
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of shalopt via groups.io Sent: Sunday, January 31, 2021 1:21 PM To: [email protected]Subject: [TekScopes] For Sale T5330-P2 CRT T5330-P2 CRT same as T64, T533 heater checks good. I have had this for 20 plus years stored in my attic. Acquired at a meteorology auction where I worked, I never had a need. So open to offers ask $40.00 plus shipping. Tubes weighs 40 oz packing additional. Contact me off list if you need. Can provide photos. -- Dennis Tillman W7pF TekScopes Moderator
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Re: User Experience of Sampling Scopes
On Sun, 31 Jan 2021, 22:42 snapdiode via groups.io, <snapdiode= [email protected]> wrote: Well, not to be "that guy", but the SD-24 uses 3.5mm connectors...
Compatible with SMA but not the same.
I have a confession to make. I am "that guy". The one who commits sacrilege by using cheap Chinese SMA connectors and cables with his 20GHz wonder-scope. And they're just fine for my needs, and they fit in my budget. The work the CSA803A does is a small part of my business so I can't justify spending lots to eke out every last picosecond. Trouble is, I live in a place which doesn't have hamfests, radio rallies or surplus equipment to speak of. So if I want used high-end gear I have to import it from somewhere which has had a decent electronics/R&D activity for a long time. That usually means USA/UK/Germany, and it's just not worth it to track down all the little bits and pieces which would be so easy to find at a rally, sadly.
And I would just like to add that I have a S-52 which makes me *almost* as
cool.
Much cooler, I reckon! Chris
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Re: User Experience of Sampling Scopes
Thanks for being ¡°that guy¡±. Not being aware of the difference can cause expensive damage, and it¡¯s one of my pet peeves.
The two connectors can mate, but the 3.5mm connector is made to much tighter tolerances. It also has an air dielectric. Mating to a poorly made (or badly abused) SMA can wreck a 3.5mm connector¡¯s ability to maintain low SWR all the way out to its TEM limit. Permanent damage can be done by a single connect-disconnect cycle.
I have sacrificial connector savers on all of my expensive gear, but occasionally a student will remove them ¡ª against the rules ¡ª to shorten a path or because they think the savers are introducing some artifacts. If they then connect a random SMA cable to the gear, those students have their lab access cards deactivated pretty quickly.
¡ª°ä³ó±ð±ð°ù²õ
Tom
Sent from my iThing, so please forgive typos and brevity.
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On Jan 31, 2021, at 1:42 PM, snapdiode via groups.io <snapdiode@...> wrote:
?Well, not to be "that guy", but the SD-24 uses 3.5mm connectors... Compatible with SMA but not the same.
And I would just like to add that I have a S-52 which makes me *almost* as cool.
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Re: User Experience of Sampling Scopes
Yes, from what I understand, SMA (usually rated to 18 GHz), with its teflon dielectric, and 3.5 mm (26.5 GHz) and 2.92 mm (40 GHz; AKA K connector), with their air dielectrics, are mechanically compatible.
Whereas the 2.4 mm (50 GHz) and 1.85 mm (67 GHz; AKA V connector) are mechanically compatible with each other but not with the SMA/3.5 mm/2.92 mm connectors. Not sure about the 1.0 mm (110 GHz), the new German 1.35 mm (86 GHz), and the crazy expensive 0.9 mm and 0.8 mm jobs. Last I knew, a 1.0 mm connector was about $1000, so not too many people have them! The only ones I have hands-on experience with (so far) are SMA and 3.5 mm connectors. $ = f^n. I don't know what n is, but it's definitely greater than 1, and probably >2.
Yep, I have an S-52 as well, but no S-6 to make a TDR yet. Darn! Had a CSA803 at work back in the day with at least one SD-24. I remember those 3.5 mm connectors. Got to be careful with them, as their center conductors can get out of alignment or broken easily.
Jim Ford
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------ Original Message ------ From: "snapdiode via groups.io" <snapdiode@...> To: [email protected]Sent: 1/31/2021 1:42:00 PM Subject: Re: [TekScopes] User Experience of Sampling Scopes Well, not to be "that guy", but the SD-24 uses 3.5mm connectors... Compatible with SMA but not the same.
And I would just like to add that I have a S-52 which makes me *almost* as cool.
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On Sun, Jan 31, 2021 at 10:22 PM, Jean-Paul wrote:
Notice that a "short legnth of RG/58" is unsuitable for accurate calibration.
A precision 50 cm 50 Ohm like Tektronix 012-0482-00 is preferred.
finally a wideband 10-20 db in-line 50 ohm attenuator like Mini-Circuits
HAT-20 can reduce VSWR reflections that affect the measurements.
A Tek SG504 does a pretty good job as well. Raymond
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Re: User Experience of Sampling Scopes
On Sun, Jan 31, 2021 at 10:09 PM, Miguel Work wrote:
These page may be of your interest:
Thanks Miguel, interesting! Raymond
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Raymond Domp Frank
Jean-Paul