500uV/Div Oscilloscopes

[Jon_Paul_Clarke]

Evening all,
                I've been trying to look for other models of CRO that have the golden "500uV/div" sensitivity for the channel inputs, but I have only gleaned a few model numbers from Dave's video rants/CRO p0rn/Interweb debates. They are:

1. The venerable Tektronix 2225
2. The Hybrid beasty Tektronix 2211
3. Possibly the 2214?
4. The sexy Tektronix 2440
5. The Tektronix 7000 series (with appropriate plug-ins)
6. The rock solid Hitachi V-1050F
7. Others?...

This is about as many as I could get, does anyone else no of other Models/Makes that have this input sensitivity?
Also, I'm trying to get my hands on a 100MHz model for all-round work. I know that there are many DSO's out there that would meet these criteria but I would like something Analogue to cut my teeth on.

Thanks in advance
Jon

[robrenz]

Tek 5000 series with appropriate plugin

[Jon_Paul_Clarke]

Ah, right. Of course. I forgot about the 5000 series.
Thanks robrenz.

[plesa]

What about LeCroy DA1855A ?

[lapm]

Sounds like someone needs to build small box to boost signals in front of oscilloscope... I wonder how terrible demanding that would be considering bandwidth requirements and signal intergity...

[robrenz]

To be done well is not cheap as evidenced here at about $2600.00

[EEVblog]

Sounds like someone needs to build small box to boost signals in front of oscilloscope... I wonder how terrible demanding that would be considering bandwidth requirements and signal intergity...

This has been one of my to-do project for a long time.
Last I had a brief look at it, I think 20MHz (typical test gear noise measurement bandwidth) was quite doable for x10
That would give any scope at least 500uV/DIV, most 100uV/DIV

[Jon_Paul_Clarke]

Good point about the sensitivity boost before the front end via probe or black box contraption. I overlooked that because I thought that it was "cheating". I guess there's no such thing in electronics as long as it's soldered/crimped properly. Eh, Dave?

[Jon_Paul_Clarke]

LeCroy DA1855A, you say? Thanks. I'll go and google that now.

[robrenz]

Very versatile bit of kit but only 10X gain yet good for very high voltage with proper probes and the XC100 10X/100X box. has built in precision DC offset. Usually around $900.00 but I snagged this one with a $300.00 offer long ago.

[plesa]

Very versatile bit of kit but only 10X gain yet good for very high voltage with proper probes and the XC100 10X/100X box. has built in precision DC offset. Usually around $900.00 but I snagged this one with a $300.00 offer long ago.

Would you mind to do teardown of 1855?

[robrenz]

I am not really qualified to do a worthwhile teardown  :-[and this has some very high impedance stuff inside so I feel safer leaving alone.   Just like I am not teardown of my 2450SMU anytime soon either, I just don't trust myself to not do something stupid in the process.

[jlmoon]

Very versatile bit of kit but only 10X gain yet good for very high voltage with proper probes and the XC100 10X/100X box. has built in precision DC offset. Usually around $900.00 but I snagged this one with a $300.00 offer long ago.

Thats a LeCroy jDA1855A diff amp with a new wrapper.. ..

[robrenz]

Actually an OLD wrapper, Lecroy bought Preamble.

[jlmoon]

ah,  learn something new everyday!   They sure are proud of those devices.. 

[Jay_Diddy_B]

Hi,

I would add the Tektronix AM502 in a suitable mainframe TM501- TM506 to the list of pre-amplifiers to consider.

This is a differential amplifier with The gain can be set from 1 to 100,000 in the 1,2, 5 sequence

It has two filters the HF corner can be set from 100 Hz to 1 MHz, 9 steps in 1-3 sequence.
The LF corner can be set from 0.1 Hz to 10 kHz, 6 steps in 1-10 sequence.

Limiting the bandwidth can sometimes help dig a signal out of the noise floor.

This is very similar to the 5A22 and 7A22 oscilloscope plugins.

The AM502/TM50x mainframe can be used to increase the sensitivity of any oscilloscope.

Link: http://www.barrytech.com/tektronix/tektm500/tekam502.html


Regards,

Jay_Diddy_B

[Dave Turner]

Dave

How about it - design a 500mv/division or better amplifying probe combined with a differential probe; all switchable of course?  It's sort of similar to the microamp.

It's way past my ability but just possibly could bridge a gap between reasonable and out of reach epuipment for the majority.

[Electro Fan]

Evening all,
                I've been trying to look for other models of CRO that have the golden "500uV/div" sensitivity for the channel inputs, but I have only gleaned a few model numbers from Dave's video rants/CRO p0rn/Interweb debates. They are:

1. The venerable Tektronix 2225
2. The Hybrid beasty Tektronix 2211
3. Possibly the 2214?
4. The sexy Tektronix 2440
5. The Tektronix 7000 series (with appropriate plug-ins)
6. The rock solid Hitachi V-1050F
7. Others?...

This is about as many as I could get, does anyone else no of other Models/Makes that have this input sensitivity?
Also, I'm trying to get my hands on a 100MHz model for all-round work. I know that there are many DSO's out there that would meet these criteria but I would like something Analogue to cut my teeth on.

Thanks in advance
Jon

Any idea why Tektronix only offered 500uV/Div on these relatively few models, and why they picked these particular models vs. others?

[rf-loop]

This is not exactly what asked but still handy in some cases.

Tektronix all 24xx (and some other old models) analog scopes have  CH2  signal output (rear panel).
20mV/div to 1Mohm and 10mV/div to 50ohm.

CH1 and CH2 can use  cascaded.

Connect signal under test to CH2 input. (you can even shut off CH2 if no need watch directly, signal is still routed to its output.)

Connect  CH2 output to CH1 input. Set trigger source to CH1.


For 1mV/div and 500uV/div:
Set CH2  for 5mV/div and CH2 output to CH1 input
Set CH1  for 2mV/div
Now signal (true input is CH2) is 1mV/div on the screen  if CH1 impedance was set for 50ohm (better response) or 500uV/div if CH1 input is set for 1Mohm.

For 400uV/div and 200uV/div:
Set CH2 for 2mV/div and CH2 output to CH1 input.
Set CH1 for 2mV/div
Now signal (true input is CH2) is 400uV/div on the screen  if CH1 impedance was set for 50ohm (better response) or 200uV/div if CH1 input is set for 1Mohm.

Of course oscilloscope cursors show values related to CH1 settings and user need think right level.

Not perfect and also frequency response is some amount reduced (cascaded CH1 2mV and CH2 2mV response and if not 50ohm then also this impedance mismatch (cable lenght etc)

In some cases this is still useful.

[plesa]

I am not really qualified to do a worthwhile teardown  :-[and this has some very high impedance stuff inside so I feel safer leaving alone.   Just like I am not teardown of my 2450SMU anytime soon either, I just don't trust myself to not do something stupid in the process.

I understand. Few internal pictures will be appreciated,I'm just currious. About teardown of SMU, don't afraid, if you are removing covers it is OK. I make this type of teardown on my 2636B and several picoammeters which I need to repair.
I hope Dave will make the teardown of the Agilent SMU sooner or later.

[David Hess]

Any idea why Tektronix only offered 500uV/Div on these relatively few models, and why they picked these particular models vs. others?

There were at least two different series within the 22xx line and the 2201, 2205, 2210, 2211, 2214, and 2225 formed one of them with 25pF inputs and 20 MHz or 50 MHz input bandwidths.  Of those the later 4 included x10 vertical magnification which served double duty as a 5 MHz bandwidth limit that could be applied to individual channels instead of all of them together.

The other 22xx oscilloscopes had 20pF inputs and 60 MHz or 100 MHz bandwidths.

[David Hess]

I am really only familiar with the Tektronix products so I will just list the ones that come to mind:

The 2225 sub-series within the 22xx series oscilloscopes which includes the 2210, 2211, 2214, and 2225 all have x10 vertical magnification which also serves as a 5 MHz bandwidth limit.  The 2225 is analog only but the other three combine analog operation and digital storage.

The 7A15A (but not the 7A15!) single channel 80 MHz vertical amplifier plug-in for the 7000 series mainframes has x10 vertical magnification which also limits the bandwidth to 10 MHz.

The 7A22 differential 1 MHz vertical amplifier plug-in for the 7000 series.

The AM502 differential 1 MHz amplifier for the TM500 series test instruments duplicates the capabilities of the 7A22 for any oscilloscope.

Various 5000 series vertical plug-ins.

The vertical output on 7000 mainframes provides a roughly calibrated 25mV/div signal and may be used to cascade vertical amplifiers for increases sensitivity however noise may be a problem.  There are other oscilloscopes which can do this as well.

Honorable mentions should go to the 2216 which is a 4 channel 60 MHz (10 MHz at 1mV/div and 2mV/div) combination analog and digital storage oscilloscope and supports 1 mV/div sensitivity but is only listed in the 1995 catalog.  And the 7A13 differential comparator which also supports a 1 mV/div sensitivity with a separate 5 MHz bandwidth limit.

[David Hess]

Good point about the sensitivity boost before the front end via probe or black box contraption. I overlooked that because I thought that it was "cheating". I guess there's no such thing in electronics as long as it's soldered/crimped properly. Eh, Dave?

Many oscilloscopes essentially do this internally by changing the gain of the input preamplifier which also has the effect of lowering the bandwidth.  On the often discussed 2225, this is done by lowering the load (increasing the resistance) at the output of a transconductance stage to multiply the gain by 10 times.  Other oscilloscopes like the 2235 series do this for their highest sensitivity setting or settings by lowering the emitter resistance in a transconductance stage by a factor of 2.5 (5mV/div to 2mV/div) for a minor bandwidth hit and this is common in both old and modern DSOs which often have a different bandwidth for each of their higher sensitivity settings.

[owiecc]

Would you mind to do teardown of 1855?

I have disassembled one. Needed to change the fan on it. I can show you few photos now, more will come soon. I need to do proper hi-res photos of the boards. Note the hidden button inside

[David Hess]

Sounds like someone needs to build small box to boost signals in front of oscilloscope... I wonder how terrible demanding that would be considering bandwidth requirements and signal intergity...

This has been one of my to-do project for a long time.
Last I had a brief look at it, I think 20MHz (typical test gear noise measurement bandwidth) was quite doable for x10
That would give any scope at least 500uV/DIV, most 100uV/DIV

I looked at this as well but differential inputs, high common mode range, and high common mode rejection are too useful to leave out when dealing with low level measurements which more than doubles the complexity so I chose the 7A22/AM502/7A13 route as being more economical.

I forget which exactly but I believe the same engineer who designed the mentioned Tektronix differential amplifiers also designed the Preamble (bought by LeCroy) amplifiers.

I think 20 MHz is a little optimistic but excess noise would not matter when bandwidth limiting and noise reduction is available from a DSO.  The only caveat I would add to a simple x10 probe amplifier is that it should have a compensation adjustment so the probe can be used with it and the oscilloscope without further compensation adjustment.