Hi all,

I've tried to gain an answer to this question from Owon and Mouser (UK) but neither company seem intrerested in emailing me back with assistance.

The problem is.. I've managed to crack one of my scope probes so would like to replace the ones my scope came with, preferably with some new Pomona ones. I should be very grateful if somebody could please take a look at the following Mouser link, and tell me which pomona probes would be suitable for my scope please?

Pomona probes...http://gb.mouser.com/_/N-scv7?Keyword=oscilloscope+probes&FS=True&Ns=Pricing|0

Pomona probe specs... http://www.pomonaelectronics.com/pdf/d4550b-sp150b_6_01.pdf


My original probes have what looks like a Tektronix number on them (P6060 & 60MHz)

My scope specs are....

Bandwidth 25MHz
Input impedance: 1MΩ ±2%, in parallel with 20pF ± 3pF

Original probes...

1x/10x
Compensation range...... 20pF - 40pF
Input resistance.......... 1Mohm +/- 2% / 10Mohm +/- 2%
Input electrical capacity... 1x = 85pF - 115pF / 10x = 14.5pF - 17.5pF


I can supply more info and pics of my probes if required?

Thanks for your help guys

orb

 

I just got a set of 100 MHz probes off fleabay for $6 plus shipping. They look like clones of Tektronix 1X/10X probes. They work fine, can't complain.

http://cgi.ebay.com/Two-Oscilloscop...tem&pt=LH_DefaultDomain_0&hash=item2a085ebb25

 

Yes those look the same as mine, however they are pretty cheap ones, and since I've broken one of mine.. I'd like to get myself some good ones. I know Pomona ones are pretty good as I use them with my meter.

I'd just like someone who has experience of probe specs to check out the pomona probes AND my scope specs to see which are suitable, as it's important for both scope & probes are compatible.

regards

orb

 

Still need help to original post guys please.

Sorry for double post but couldn't edit previous one as the button went missing

 

Any of the Pomona 1/10 will do a reasonable job - but not if you are doing above 300Vpk or want specified max B/W.

Always cal the probes, and do a swap comparison if you get into high spec applications.

Ciao, Tim

 

Any of the Pomona 1/10 will do a reasonable job - but not if you are doing above 300Vpk or want specified max B/W.

Always cal the probes, and do a swap comparison if you get into high spec applications.

Ciao, Tim

I don't understand my friend. Why so many Pomona probe variations then?

I do understand the max bandwidth part. However I have read that it is very important to get a set of probes with the correct attenuation and compensation range too. And this is what is confusing me as the Pomona spec page I linked to doesn't show probes specs that are close to my scope specs as regards attenuation and input capacitance etc.

Please advise further

Kind Regards

orb

 

If you want to get up on o'scope probes and such, look at the offerings from Tek - http://www.tek.com/products/accessories/

 

If you want to get up on o'scope probes and such, look at the offerings from Tek - http://www.tek.com/products/accessories/

Please don't take this the wrong way beenthere, but did you read my first post?
I know what I'm after, I just want to make sure the Pomona probes I order are correct ones for my scopes specs. I'm a noob when it comes to this sort of thing you see and I need some help from you guys so that I don't order something that won't work properly, or is the wrong spec.

Regards

orb

 

I have the exact same probes (100MHz) mentioned by bountyhunter. Been using them about 2 months, no problems so far, but I haven't been using them for precision applications, so can't confirm their accuracy (manual says 1% DC accuracy) or their -3dB bandwidth etc. I measured the FSB clock (approximately a sine wave) of a computer using them, at 133 MHz, with no problems, on my 100 MHz scope, which was pretty cool.

As far as I understand, pretty much any scope probe will work with any other scope, provided they aren't 'special' like some kind of FET input type or differential or something like that, and that they have the right connector.

Most probes have adjustable capacitance settings as a trimpot. The impedance is not usually a problem because most scopes in my experience are not more than 0.5% accurate (mine is 1.5%, a new scope will do about 1%) when it comes to measuring voltage. Just make sure that if you buy a 1 megohm probe you use it with a scope with 1 megohm input impedence. Usually the probe lets you select between a 9 megohm resistance and zero, in the 10X and 1X modes.

 

Ok Thanks tom for explaining, I think I understand.

The confusing part for me is this input capacitance range. I was lead to believe this was a critical part in choosing a probe?

Am I right in thinking then that... As long as my scopes input capacitance (20pF +/- 3pF) is between the the probes compensation range (10 - 60pF) which it is. I'll be fine choosing the cheapest (£70 ) 4550B probes?

Kind Regards

orb

 

4550B looks like the best choice to me.
The input capacitance column refers to the capacitance at the probe tip for X1 and X10 attenuation. The 4550B has 64pF input C at X1, and 10.5pF input C at X10, for a scope with 20pF input C, which yours has.

 

OK so just to confirm please..

I needn't worry about all the other figures in the Pomona chart. And the the '4550B' probes specs are fine for a 25MHz scope with a Input Impedance of... 1MΩ ± 2%, in parallel with 20pF±3pF?

Regards

orb

 

OK so just to confirm please..

I needn't worry about all the other figures in the Pomona chart. And the the '4550B' probes specs are fine for a 25MHz scope with a Input Impedance of... 1MΩ ± 2%, in parallel with 20pF±3pF?

Regards

orb

The 100MHz X10 probe BW, in conjunction with the 25MHz scope, will reduce the system BW to about 24MHz.
The 15MHz X1 probe BW, in conjunction with the 25MHz scope, will reduce the system BW to about 12MHz. Note that none of the probes in the table you posted have a readout actuator pin. On some scopes, this pin, if present, will illuminate the appropriate scale factor on the scope's attenuator. I don't know if any of the TEK scopes have this function for the X1/X10 probes.

 

I don't know if any of the TEK scopes have this function for the X1/X10 probes

The 475 had that function. My 2221 does not.

 

Ah ok, This is what I was worried about you see in not getting probes that where 100% compatible. I had an idea all those numbers meant something

OK.. I guess to be on the safe side then I should just get a similar pair of probes to the ones I have now from ebay. I can get some tek clones (same as I have now) for around £6. At least this way I'll not loose any BW by getting the same type.

Thanks guys

Regards

orb

 

I use these as well (from the same seller).

No problems at all.

Daniel.

I just got a set of 100 MHz probes off fleabay for $6 plus shipping. They look like clones of Tektronix 1X/10X probes. They work fine, can't complain.

http://cgi.ebay.com/Two-Oscilloscop...tem&pt=LH_DefaultDomain_0&hash=item2a085ebb25

 

Ah ok, This is what I was worried about you see in not getting probes that where 100% compatible. I had an idea all those numbers meant something

OK.. I guess to be on the safe side then I should just get a similar pair of probes to the ones I have now from ebay. I can get some tek clones (same as I have now) for around £6. At least this way I'll not loose any BW by getting the same type.

Thanks guys

Regards

orb

What's the part number of the probes you are replacing? I suspect they have similar bandwidth limitations.

The X1 BW of the probes on Ebay is only 6MHz.

 

The probes that came with the scope are tektronix copies I think and are 60MHz probes. The part number is P6060.

EDIT: My currenty probes specs are..

DC: Up to 6 MHz (x1) and (up to scopes full BW which will be 25MHz (x10)
Compensation range: 20pF - 40 pF
Input capacity: 85pF - 115pF (1x) 14.5pF - 17.5pF (x10)