Author Topic: new killer scope in town - a true game changer from R&S - RTB2002 & RTB2004  (Read 809604 times)

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Offline Octane

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So we have to consider any scope with MLCCs in the channel frontend being cheap? >:D The manufactures should choose types which are less susceptible to microphonics at least.

Or mount them on their side  ;D (it works)
Not exactly production friendly though. Although if you want to really annoy your assembler, request it  >:D
Sorry if I am asking a dumb question... If the PCB is mounted vertical to the base of the scope (like the Keysight 1000X series), isn't it equivalent to having the multilayer caps mounted on their side?

I would guess it depends on the relative orientation between the cap and the PCB. Not the overall orientation. If you excite flexing vibrations in the PCB then bending a "flat" cap is easier then a cap that's higher then wide. See beams with different aspect ratios...
I am testing my EDUX1002G scope and it is affected by the Wack-a-Scope feature.  But if I connect a 50ohm BNC terminator in CH1, then it is Wack-immune.  If I turn both CH1 (still with 50 ohm terminator at input) and CH2 ON, then I Wack the scope and I only see the issue on CH2.

I guess this makes sense. Since it is a piezoelectric effect you can easily "short" the voltage with the 50 Ohm resistor.
Piezos can get you high voltages with basically no current through them, as long as you are not driving them at there mechanical resonance.
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Offline norks

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Dave, (off topic but...) in your experience did sorbothane live up to its hype and outperform other common vibration insulators? Or was it only marginally different in use?
 

Offline TK

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So we have to consider any scope with MLCCs in the channel frontend being cheap? >:D The manufactures should choose types which are less susceptible to microphonics at least.

Or mount them on their side  ;D (it works)
Not exactly production friendly though. Although if you want to really annoy your assembler, request it  >:D
Sorry if I am asking a dumb question... If the PCB is mounted vertical to the base of the scope (like the Keysight 1000X series), isn't it equivalent to having the multilayer caps mounted on their side?

I would guess it depends on the relative orientation between the cap and the PCB. Not the overall orientation. If you excite flexing vibrations in the PCB then bending a "flat" cap is easier then a cap that's higher then wide. See beams with different aspect ratios...
I am testing my EDUX1002G scope and it is affected by the Wack-a-Scope feature.  But if I connect a 50ohm BNC terminator in CH1, then it is Wack-immune.  If I turn both CH1 (still with 50 ohm terminator at input) and CH2 ON, then I Wack the scope and I only see the issue on CH2.

I guess this makes sense. Since it is a piezoelectric effect you can easily "short" the voltage with the 50 Ohm resistor.
Piezos can get you high voltages with basically no current through them, as long as you are not driving them at there mechanical resonance.
Another test: 10Hz 2mVpp sinusoidal signal from WaveGen, direct BNC-BNC cable to CH1.  Both CH1 and CH2 ON.  Display persistence infinite.  Wack the scope (quite hard) and CH1 signal does not seem to be affected, only CH2.
 

Offline Octane

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So we have to consider any scope with MLCCs in the channel frontend being cheap? >:D The manufactures should choose types which are less susceptible to microphonics at least.

Or mount them on their side  ;D (it works)
Not exactly production friendly though. Although if you want to really annoy your assembler, request it  >:D
Sorry if I am asking a dumb question... If the PCB is mounted vertical to the base of the scope (like the Keysight 1000X series), isn't it equivalent to having the multilayer caps mounted on their side?

I would guess it depends on the relative orientation between the cap and the PCB. Not the overall orientation. If you excite flexing vibrations in the PCB then bending a "flat" cap is easier then a cap that's higher then wide. See beams with different aspect ratios...
I am testing my EDUX1002G scope and it is affected by the Wack-a-Scope feature.  But if I connect a 50ohm BNC terminator in CH1, then it is Wack-immune.  If I turn both CH1 (still with 50 ohm terminator at input) and CH2 ON, then I Wack the scope and I only see the issue on CH2.

I guess this makes sense. Since it is a piezoelectric effect you can easily "short" the voltage with the 50 Ohm resistor.
Piezos can get you high voltages with basically no current through them, as long as you are not driving them at there mechanical resonance.
Another test: 10Hz 2mVpp sinusoidal signal from WaveGen, direct BNC-BNC cable to CH1.  Both CH1 and CH2 ON.  Display persistence infinite.  Wack the scope (quite hard) and CH1 signal does not seem to be affected, only CH2.

WaveGen is 50 Ohm, isn't it?
W4MFT
 

Offline vokars

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Dave, (off topic but...) in your experience did sorbothane live up to its hype and outperform other common vibration insulators? Or was it only marginally different in use?

I am using rubber granulate matte typically used for dampening washing machines. Its the best for the price that I know. The critical issue with dampening are always the bass frequencies that have a lot of energy and that are also included in the spectrum of shock bursts. Here much helps much. Therefore I think the affordable rubber granulate has an advantage if you need much.
 
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Online mikeselectricstuff

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With a 50R terminator on the input the issue completely disappears - only a hard wack on the connector produces maybe 1 div, so looks like energy transer into a very early part of the input stage.
Even plugging in a standard 10:1 probe with its tip shorted reduces the issue very substantially.

If you're interested in low-level signals, chances are you're going to be usjng a fairly low impedance source, but even with a normal probe it's pretty much a non-issue.

I almost wonder if it may at least in part be the dielectric of the BNC connector


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Online mikeselectricstuff

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Dave - can you try repeating your test with the R&S probe plugged in, on 10:1 and the tip shorted.
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Offline Octane

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I'm not aware of any piezoelectrically active plastic dielectrics if not specifically made polar, like in electret microphones? Am I wrong?
Or are you thinking more along the way of triboelectricity?
« Last Edit: March 29, 2017, 06:17:55 pm by Octane »
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Offline TK

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I almost wonder if it may at least in part be the dielectric of the BNC connector
You might be right... Connect a BNC cable to CH1 and Wack the BNC on the other end of the cable...
 

Offline vokars

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I almost wonder if it may at least in part be the dielectric of the BNC connector
You might be right... Connect a BNC cable to CH1 and Wack the BNC on the other end of the cable...

Yes: Beating just a BNC cable creates 5mV spikes.
 

Offline Messtechniker

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Could it be that you are observing an old and well known
effect called "Microphonics"? Components and cables are known to be
microphonic to a certain extent. Simply tap on a cable carrying a
unbalanced low level microphone signal and you will see what I mean.

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Offline piranha32

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I almost wonder if it may at least in part be the dielectric of the BNC connector
You might be right... Connect a BNC cable to CH1 and Wack the BNC on the other end of the cable...
The cable itself is not immune to the effect either. Dave did in the past some experiments with Tek scope and probes, and he also whacked the cable on the bench. And yes, he's got a response on the screen (rewind to 8:00): https://youtu.be/KFCRB4d991E?t=8m4s

Offline Octane

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Yes, see earlier posts in this thread. And I guess we are drifting a little bit off path here.
The main issue was that the RTB2k scope seems to be very sensitive to this microphonics when just tapped on the touchscreen.
But this may not be too relevant, since this seems only to make problems when the channel is open.
W4MFT
 

Offline ebastler

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Could it be that you are observing an old and well known
effect called "Microphonics"? Components and cables are known to be
microphonic to a certain extent. Simply tap on a cable carrying a
unbalanced low level microphone signal and you will see what I mean.

I think it is pretty clear that all the effects discussed in the past couple of pages fall in the "microphonics" category, and the term has been mentioned a couple of times in the prior posts. Cables, capacitors, vacuum tube grids etc. can translate mechanical vibrations into electrical signals, like a (typically capacitive) microphone.

Your description is a bit misleading -- you don't need to connect an actual (intentional) microphone to experience (undesired) microphonics; the afore-mentioned components alone are enough to produce the effect.
 

Offline MrW0lf

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But this may not be too relevant, since this seems only to make problems when the channel is open.

Theres huge uncharted territory between open channel and shorted channel. This need scientific approach. Suggest 3D chart with following axes: X - frequency of stimulation (can be done using ultra powerful piezo etc, rigidly attached to scope chassis), Y - channel impedance ("load"), Z - scope response. Should take no more than a week of testing  :P
Of course there should be 3D acceleration sensors in various places to analyze stimulation wave propagation etc. Ideally it would be not constant wave but single soliton, otherwise standing waves could build up. Altering resonant frequency of chassis, PCB by adding sensors should be also taken into account.
So if done properly bit more than week, maybe year or so...
« Last Edit: March 29, 2017, 07:33:40 pm by MrW0lf »
 

Offline Octane

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But this may not be too relevant, since this seems only to make problems when the channel is open.

Theres huge uncharted territory between open channel and shorted channel. This need scientific approach. Suggest 3D chart with following axes: X - frequency of stimulation (can be done using ultra powerful piezo etc), Y - channel impedance ("load"), Z - scope response. Should take no more than a week of testing  :P

Hehe, true. But since piezo-/triboelectric sources are most of the time quite high impedance I assume that in most cases it will not be a problem. Anyways, I'm at least trying to convince myself of this, so that I can still be looking forward in getting the RTB2004.

Maybe Mike and Dave will have to say more soon, since they can already use the RTB in their daily business.

P.S.: only 2 days left to the "expected shipping" date... let's see if it is true.
« Last Edit: March 29, 2017, 07:22:40 pm by Octane »
W4MFT
 

Offline corax

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Re: The promo deal IS still on at Newark for USA buyers
« Reply #766 on: March 29, 2017, 07:35:09 pm »

Just a reminder that the $2080 promo package deal on the RTB2004 *is* still going on at Newark, but apparently they can only sell into the USA market.  They have a pricing mixup with their system though.  I exchanged some PMs today with a fellow buying one and Rich from R&S.  The website shows $2080 here

http://www.newark.com/rohde-schwarz/rtb2k-com4/rtb2004-complete-bundle-300-mhz/dp/08AC3745?ost=rtb2004&categoryId=800000047008&searchView=table&iscrfnonsku=false

But when you put it in your cart the number may flip to the $7900 (or $8600 I just learned) list price for the package.  Or it may show the correct price in the cart and $8600 then show up in the email confirm.  The system is grabbing from a database that doesn't have the promo pricing now that the deal is over at the other two US distributors.  Rich says you have to call into Newark's sales department and talk to them to get it priced correctly, until they can get the database thing worked out.


I ordered one from Newark yesterday, and as predicted, the email confirmation came back today with a total of $7920 (no sales tax here).

After a bit of time on the phone with a confused Newark customer service rep, the order was cancelled/replaced and a confirmation came back with the correct price.
He stated that they had these in stock; shipping date is supposed to be tomorrow.

 
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Offline tautech

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One would suspect any scope with BNC's that are fastened to a chassis to exhibit lower microphonics.
Mentioned by a member was his TDS2000, Dave showed an old TDS1000 and all the Siglent's I have had apart also have nuts on the BNC holding them to a metal chassis.
Both the Teks mentioned above have BNC's fastened to chassis.
As yet I haven't looked inside a SDS1kX but I suspect they will have nuts on their BNC's too and it seems this construction method is superior in regard to lower microphonics. Can't even have a look at any of the SDS1kX....all sold out.  :(  :)

Very interesting vid Dave, thanks for taking the time to do it.
Whack a scope  :-DD
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Online mikeselectricstuff

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But this may not be too relevant, since this seems only to make problems when the channel is open.

Theres huge uncharted territory between open channel and shorted channel. This need scientific approach. Suggest 3D chart with following axes: X - frequency of stimulation (can be done using ultra powerful piezo etc, rigidly attached to scope chassis), Y - channel impedance ("load"), Z - scope response. Should take no more than a week of testing  :P
Of course there should be 3D acceleration sensors in various places to analyze stimulation wave propagation etc. Ideally it would be not constant wave but single soliton, otherwise standing waves could build up. Altering resonant frequency of chassis, PCB by adding sensors should be also taken into account.
So if done properly bit more than week, maybe year or so...
You could test til the cows come home but there is only really one thing that matters - highest sensible input impedance and highest sensible impact.
A quick test with a x10 probe suggests it's a non-issue.
For low-level measurements chances are you'll be using 1x probing, and your source is going to need reasonably low source impedance due to the capacitance of a x1 probe. So it's even less of an issue.
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Offline MrW0lf

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You could test til the cows come home but there is only really one thing that matters - highest sensible input impedance and highest sensible impact.

:palm: You just ruined good science project with about 100kEUR budget! Damn! What next, maybe dismiss whole CERN-fest with some embarrassingly practical remark :( People need to feed the families!
...and while at it, why not ruin go-to-Mars project also: "theres sand with life in it in my (rainbow) cat litter box, why go to Mars :-//"

Edit: Maybe theres still hope for science, what about x100 probe? These make good use of 10bit ADC.
« Last Edit: March 29, 2017, 08:28:18 pm by MrW0lf »
 

Online thm_w

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This whole operation by Rohde & Schwarz to only offer this promotion to the USA and Canada really stinks.

Grrr.

Please read the thread. Its the EU distributors that did not want to accept the deal, as they lose out on higher margins (Mike found this out).
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Offline pm.llb

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This whole operation by Rohde & Schwarz to only offer this promotion to the USA and Canada really stinks.

Grrr.

Please read the thread. Its the EU distributors that did not want to accept the deal, as they lose out on higher margins (Mike found this out).
Not true I am affraid. I've asked local R&S office directly. Price is  over 7k euro ...
« Last Edit: March 29, 2017, 09:21:32 pm by pm.llb »
 

Offline norks

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This whole operation by Rohde & Schwarz to only offer this promotion to the USA and Canada really stinks.

Grrr.

Please read the thread. Its the EU distributors that did not want to accept the deal, as they lose out on higher margins (Mike found this out).
Not true I am affraid. I've asked local R&S office directly. Price is  over 7k euro ...

If R&S, after offering the launch deal to their EU distribution partners and being turned down, decided to go around them and offer it direct in the EU that would be a huge middle finger at them. That's no way to treat your distributors.
 

Offline skench

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This whole operation by Rohde & Schwarz to only offer this promotion to the USA and Canada really stinks.

Grrr.

Please read the thread. Its the EU distributors that did not want to accept the deal, as they lose out on higher margins (Mike found this out).
Not true I am affraid. I've asked local R&S office directly. Price is  over 7k euro ...

I did read the thread.
I was with it from the very first page.

As soon as I saw the offer (see post 198) and before any one had said this was for the USA and Canada only my order had been placed and accepted.

Only after I had placed my order did all the "USA and Canada" only messages spring up.
I question Tequipment and it all seem aright then 13 days later they cancel. Not sure how long it will be until the money is return to my account!

Anyway I am going to order one from Newark and have it delivered to are facility in Toronto for shipping here.

We will see how that works out.
 

Offline skench

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This whole operation by Rohde & Schwarz to only offer this promotion to the USA and Canada really stinks.

Grrr.


Please read the thread. Its the EU distributors that did not want to accept the deal, as they lose out on higher margins (Mike found this out).
Not true I am affraid. I've asked local R&S office directly. Price is  over 7k euro ...

If R&S, after offering the launch deal to their EU distribution partners and being turned down, decided to go around them and offer it direct in the EU that would be a huge middle finger at them. That's no way to treat your distributors.

I would put it the other way around in that it's no way to treat your customers!

What is the logic in the only the North Americans having the benefit of the RTB2K-COM4 package?

It's like sticking two fingers up to the rest of the world and I am not sure that it was anything to do with the distributors. I do not think all the other distributors in the rest of the world said "no we do not want the easy business".

I suspect it's R & S giving massive discount support to the US distributors and none for anyone else.

Not that I am bitter or anything.
 


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