Help Me Pick The Right Scope...2

[JuanPC]

tequipment.net

Rigol DS2072 $839usd.
Rigol DS2102 $1143usd.
Rigol DS2202 $1626usd.***** 2GSa/s. http://www.tequipment.net/RigolDS2202.html
Instek GDS-3152 150 MHz 2 Channel $1652usd. 2.5GSa/s.
Instek GDS-3154 150 MHz 4 Channel $2012usd.***** 5GSa/s.
http://www.gwinstek.com/en/product/productdetail.aspx?pid=3&mid=7&id=1290
http://www.testequipmentdepot.com/instek/oscilloscopes/gds-3154.htm
Rigol DS4022 $2600usd.? 4GSa/s. http://www.tequipment.net/RigolDS4022.html

Hi,

I write because i need help, i´m a begginer, and i know the value of having the right tool,
but can´t decide what to buy, with the budget i have....
 
I feel bad to post this on the forum.
here is the dilema:
2GSa/s vs. 5GSa/s,
but,
2GSa/s with Big memory vs. 5GSa/s with small memory.
2GSa/s with better Ultravision vs. 5GSa/s with inferior VPO*.
?
I really love the Instek gds-3154 75ohm inputs & 5GSa/s.
want to measure SQRs from Agilent 33500B at 25MHz,
and decode some s/pdif signals running at 192Khz, "6MHz" from my soundcard.

but can´t decide, whats better for me.
UltraVision & memory or 5GSa/s & 75ohms.
Memory could replace a Logic Analizer,
but...
Impendace is very important for me, i have a Leader Analog SQR signal generator,
connected to a Drawmer D-Clock, but didn´t worked,
the idea was to see if i could measure it, vs. the freq. counter of the scope.
the Drawmer had a Hi-Z or 75ohms switch, and magically it worked at Hi-Z.
i don´t understand much about impedances, but i know 75ohms is very important for me.

Anyway...
Agilent dsox3k is out of the budget.

I had Instek gds1102A-U with big memory and i was very happy with it, far better than any other, in that $ range.
but the RT 1GSa/s was not enough, no VPO, & yes, slow cpu when multiple features are running, probes were not exactly x10,
more like x5.5, useless for "high voltage" measurents, anyway...
Rigol 2k it´s in a new league, it´s more like a 3K with a 2K price.

solution could be the DS4K.?
but is $600usd. more with 2ch & 1GSa/s less... ?
& still has no 75ohm input.
and does not have the 0.5mV/div of the 2K..?,
 i want to measure some Phono signals, later, Phono signals are very small.
also i want to align old FM radios, with a Scope, instead of the ST1000A.

Help!
I´m about to make a mistake?

Thanks.

......
*Assuming VPO in the 2OOOA is = to the 3OOO, but seems VPO in the 3K is more advanced...




***********
Found some reviews about the DS4k.

[meltbox360]

Oh good! Now I will have a thread to reference if I happen to upgrade sooner than I thought!

Logic analyzer from memory on a scope just sounds more difficult than a regular logic analyzer. At least so I have read. That is all I can really contribute right now. Time to do more research!

[larry42]

For most purposes there is no difference between 2 and 5Gsps.
Regarding 75Ohm input impedance - most scopes provide either a 50Ohm input, or you can use a through-termination.
For measuring phono stages, none of that matters.

My advice is to buy a lower cost scope until you learn more.

As for getting only 5.5:1 either you have faulty probes or you're measuring incorrectly (such as no taking into account the shunt capacitance of the probe).

[Paul Price]

Larry42, good idea to check your 75 ohm and 50 ohm terminating resistors in your scope, they seem to be reading 10x higher in value. I have not yet seen a scope with a 75-ohm termination option...hmmm...interesting!

[JuanPC]

Found an interesting article about Matching 50 to 75.

http://www.ham-radio.com/k6sti/match.htm

But Still i´m leaning towards the GDS-3154.
Rigol DS4012 is $2000usd. BUT....
according to Agilent Rule of 5 i need 125MHz.
and according to Dave Rule of 10, i need 250MHz.
DS4012 100Mhz 4GSa/s is under the minimum.
i wish i could buy the 350MHz,.

would be nice to see a 25MHz SQR with different Scopes.
generated with a good SG/ABR like Agilent 33500B.

P.S. there is no ohm font in eevblog.com  ?
Matching 50? to 75? Courier
Matching 50? to 75? Arial
Matching 50? to 75? Arial black
Matching 50? to 75? impact
Matching 50? to 75? Verdana
Matching 50? to 75? Times New Roman
Matching 50? to 75? Georgia
Matching 50? to 75? Andale Mono
Matching 50? to 75? Trebuchet MS
Matching 50? to 75? Comic Sans

[alm]

The 5-10*BW formula applies to scopes with a Gaussian response, while 2.5-4*BW is commonly quoted for scopes with a brick wall response, because they roll off frequencies beyond the BW more steeply. What kind of roll-off does the DS4000 have? One trick is that 10-90% rise time is 0.35/BW for scopes with a Gaussian roll-off, and something like 0.4-0.5 / BW for brick wall. Agilent has an app note on this.

Edit: Never mind. I was talking about the sampling rate / BW ratio, not the BW / signal repetition rate ratio.

[c4757p]

P.S. there is no ohm font in eevblog.com  ?

Lack of support for the symbol is quite common; it's often avoided in informal/commercial electronics and kept to academia and the occasional handwritten diagram. Use R or the word "ohm".

And it's not the font, anyway, the symbol is directly discarded and converted to a question mark.

[baljemmett]

P.S. there is no ohm font in eevblog.com  ?

I think the forum software (or maybe just its configuration) subscribes to the 'character encodings are hard, let's just throw in some more animated emoticons instead' school of text processing.

[JuanPC]

http://us.rigol.com/download/Oversea/DS/Datasheet/DS4000_DataSheet_EN.pdf 

[Zad]

It is scary what newcomers class as entry-level or "beginners" tools now.

It is like learning to drive and buying a Ford Focus RS. Sure, it isn't a Porsche 911 or a Ferrari, but it is way, way beyond what you need, and what you will use.

Get yourself a $100 analogue scope off Ebay, plus maybe a cheap logic analyser / bus pirate thing. Use it, abuse it, play with it. When you are ready for an all-singing all-dancing scope, you will still be able to sell your analogue scope for what you paid for it, and the current generation of scopes will all have fallen in price, and have extra added features.

[JuanPC]

The 5-10*BW formula applies to scopes with a Gaussian response, while 2.5-4*BW is commonly quoted for scopes with a brick wall response, because they roll off frequencies beyond the BW more steeply. What kind of roll-off does the DS4000 have? One trick is that 10-90% rise time is 0.35/BW for scopes with a Gaussian roll-off, and something like 0.4-0.5 / BW for brick wall. Agilent has an app note on this.

It is scary what newcomers class as entry-level or "beginners" tools now.

It is like learning to drive and buying a Ford Focus RS. Sure, it isn't a Porsche 911 or a Ferrari, but it is way, way beyond what you need, and what you will use.

Get yourself a $100 analogue scope off Ebay, plus maybe a cheap logic analyser / bus pirate thing. Use it, abuse it, play with it. When you are ready for an all-singing all-dancing scope, you will still be able to sell your analogue scope for what you paid for it, and the current generation of scopes will all have fallen in price, and have extra added features.

unless you work only with sines... 5x rule is for a 3rd harmonic "absolute minimum requirements".
to see if the square wave is properly terminated needs more than 10 harmonics, 20x the frequency, the rest is guessing.

Now i´m more disappointed than ever.    lol
150Mhz is crap, for a 25Mhz SQR.
purchasing a 500Mhz 5GSa/s scope is out of the question, for now.

Learning how to operate a human can´t be done operating on a frog.

Instek GDS-3352 350MHz 5GSa/s is $
http://www.tequipment.net/InstekGDS-3352.html
http://www.testequity.com/products/3573/
http://www.testequipmentdepot.com/instek/oscilloscopes/gds-3352.htm
Instek GDS-3502 500MHz 4GSa/s is $3994usd./$3794usd. with the INSTEKSAVE "5%"
http://www.testequity.com/products/4591/
Instek GDS-3502 500MHz 4GSa/s is $3994usd./$3395usd. with the INSTEK15OFF
http://www.testequipmentdepot.com/instek/oscilloscopes/gds3502.htm
Instek GDS-3502 500MHz 4GSa/s is $3395usd. - 5OFF
http://www.tequipment.net/InstekGDS-3502.html
Instek GDS-3504 500MHz 4GSa/s is $5014usd./$4763usd. with the 5% Promo - http://www.testequity.com/products/4592/
Rigol DS4052 500MHz 4GSa/s is $4700usd. http://www.tequipment.net/RigolDS4052.html
Rigol DS4054 500MHz 4GSa/s is $5900usd. http://www.tequipment.net/RigolDS4054.html
Rigol DS6062 600MHz 5GSa/s is $5600usd. http://www.tequipment.net/RigolDS6062.html
Rigol DS6064 600MHz 5GSa/s is $7000usd. http://www.tequipment.net/RigolDS6064.html
Rigol DS6102 1GHz 5GSa/s is $7500usd. http://www.tequipment.net/RigolDS6102.html
Rigol DS6104 1GHz 5GSa/s is $9200usd. http://www.tequipment.net/RigolDS6104.html




P.S. There is no Multi-Quote on this forum.

[larry42]

Found an interesting article about Matching 50 to 75.

http://www.ham-radio.com/k6sti/match.htm

But Still i´m leaning towards the GDS-3154.
Rigol DS4012 is $2000usd. BUT....
according to Agilent Rule of 5 i need 125MHz.
and according to Dave Rule of 10, i need 250MHz.
DS4012 100Mhz 4GSa/s is under the minimum.
i wish i could buy the 350MHz,.

would be nice to see a 25MHz SQR with different Scopes.
generated with a good SG/ABR like Agilent 33500B.

You realise that they put men on the moon with 50MHz scopes, right?

Looking at square waves might be interesting, but you don't need a 350MHz scope for that.

Buy a 100MHz scope with say 1M of memory and learn something.
If you're dabbling in audio this is fine.

I

[larry42]

Found an interesting article about Matching 50 to 75.

http://www.ham-radio.com/k6sti/match.htm

But Still i´m leaning towards the GDS-3154.
Rigol DS4012 is $2000usd. BUT....
according to Agilent Rule of 5 i need 125MHz.
and according to Dave Rule of 10, i need 250MHz.
DS4012 100Mhz 4GSa/s is under the minimum.
i wish i could buy the 350MHz,.

would be nice to see a 25MHz SQR with different Scopes.
generated with a good SG/ABR like Agilent 33500B.

You realise that they put men on the moon with 50MHz scopes, right?

Looking at square waves might be interesting, but you don't need a 350MHz scope for that.

Buy a 100MHz scope with say 1M of memory and learn something. If you're dabbling in audio this is enough.

I'm a professional engineer and also own a small company and even I don't really need more than the Hameg 1524, 4 channel 150MHz combined with a HP 33521A for when it comes to scope and signal generator. My day job as R&D manager of a medical ultrasound company only requires a 200MHz scope, and that's doing state of the art development.

Spend your money on what you like, but there is no way that *you* *need* more than a 100MHz scope.
How to decide:
1. What's my need?
2. What's my budget?

Is 2000 USD too expensive, and you're not making money on it (see 1.)? Well then don't buy a 2000 USD scope. Simple. But I want a 2000 USD scope. Well then save your money and buy one in the future.

"Learning how to operate a human can´t be done operating on a frog."
Right, because first year medical students learn surgery on humans?

[KedasProbe]

want to measure SQRs from Agilent 33500B at 25MHz,
and decode some s/pdif signals running at 192Khz, "6MHz" from my soundcard.

Maybe you want to check the BW of the Agilent 33500B first.... (before 'wrongly' choosing your scope)

[alm]

unless you work only with sines... 5x rule is for a 3rd harmonic "absolute minimum requirements".
to see if the square wave is properly terminated needs more than 10 harmonics, 20x the frequency, the rest is guessing.

Note that these rules mostly originated from the analog scope days, and where for decent representation on an 8x10 cm CRT, not for quantitative measurements. The front-end rolls off frequencies beyond its rated bandwidth, but will still let some of them through. The number of harmonics highly depends on the rise time of the signal, since real square waves have a finite edge rate. For square waves, it's better to compare rise times. Agilent has an appnote that mentions scope rise time / signal rise time ratio for a certain accuracy in rise time measurements.

Maybe you want to check the BW of the Agilent 33500B first.... (before 'wrongly' choosing your scope)

Indeed. You shouldn't exactly need a 150 MHz scope to observe the signal from a 33500B.

[ftransform]

Dude you should save your money for a few years so you can get a nice scope, you won't get anything done with any of that junk. Probing sound cards is serious business requiring serious equipment. It's the 21st century, electronics is a highly evolved industry you can't please your woman with that thing you have right now, she laughs at it with her girl friends.

Granted, I do get annoyed when I look at my 1052e after watching dave and mikes videos, but only because I have a feeble mind.
I also have this feeling that free electron is actually trolling on juanpc but this is a completely baseless accusation

[JuanPC]

You realize that they put men on the moon with 50MHz scopes, right?

Looking at square waves might be interesting, but you don't need a 350MHz scope for that.

Do You realize that making a color video camera is harder than sending a men to the moon?

Going to the moon was first.
FullHD video was 40 years later.

That was the reason video could not be faked, there was no technology to fake it.

[saturation]

??

Minor off topic,  there was color TV back when Apollo began.   Apollo 10 was the first to broadcast live color TV from the moon.   Except for Apollo 11 and a few others on the moon, most missions broadcasted in color, live.  I saw them all, live, and naturally will never forget it.  Now, was it all a hoax  , I leave for others to argue 



Back to topic ..

[vk6zgo]

You realize that they put men on the moon with 50MHz scopes, right?

Looking at square waves might be interesting, but you don't need a 350MHz scope for that.

Do You realize that making a color video camera is harder than sending a men to the moon?

Going to the moon was first.
FullHD video was 40 years later.
That was the reason video could not be faked, there was no technology to fake it.

No it isn't---colour studio cameras were common,if a bit huge ,by 1969.
The USA had been transmitting in NTSC from the mid 1950s,the UK went to colour in 1969.
I think France started SECAM about the same time.

"Full HD" is a "red herring"--NTSC,PAL,or SECAM could produce a good quality picture which is
not much worse than HD.
We tend to kid ourselves about how much better HD is!

Of course,portable colour TV cameras were some years off,but the "hoax theory" says it was done in a studio,anyway!

Apart from his mistake about colour TV,the guy in the video is "spot on",though.

Storage of the extremely long video segment,then playing it back at a lower speed was beyond the capabilities of Video Tape Recorders of the time,because they were not designed to do this.
Neither were TV cameras which could record at a faster than normal rate available,so that option was not available,either.

Cine film was a mature technology & could do the job,but as he says,used huge lengths of film
when filming at a faster than normal rate.
Film,although very good,has a number of artifacts which could have showed up,giving the game away.

Finally,the large number of people involved in such a hoax,makes it impossible to carry out.

Getting away from the pictures,the spacecraft was tracked by people all over the globe,most of
them non-Americans,or even NASA employees.

The USSR would have almost certainly have tracked them as well,& would have been delighted to catch the USA out!