Oscilloscope probes - educate me!

[dbxdx5]

I just picked up a used Tektronix 2336 100 MHz scope, minus a set of probes. This is my first scope and need some guidance. Would a 150 MHz set like these from Probe Master be appropriate?

http://probemaster.com/4900-oscilloscope-probe-basic-kit-150-300-mhz/

If not, what features should I look for, i.e. fixed vs. switched, readout, etc? Trying to keep the $$ outlay low, but still want decent quality.

Thanks

 

[whoaru99]

With a 100MHz scope not sure why you'd pay extra for 150 or 300MHz probes? Won't hurt as long as the capacitance are compatible, but don't believe there is any practical benefit otherwise.

 

[dbxdx5]

With a 100MHz scope not sure why you'd pay extra for 150 or 300MHz probes? Won't hurt as long as the capacitance are compatible, but don't believe there is any practical benefit otherwise.

Agreed. I was only looking at the 150 MHz probes because I think they're the lowest in the Probe Master 4900 model range, which seemed to be a bit better quality than the 3900 series.

 

[whoaru99]

Far as the probes...dunno about those. Last probes I ordered were TPI brand.

 

[dbxdx5]

Thanks. I'll check out what they have.

 

[Martin.M]

when the bandwith of the probe is higher then the of the scope, this is always better then 1:1.
Important is:
The input resistance must be compatible (mostly 1M)
And the compensation range. On your scope input is written: 1M + (15pF?)
Useful is any probe what is enough bandwith, 1M, and can compensate the 15pF from the scope.
The best is, always to use a 10:1 with 1m cable lenght.

chinese probes buyed from the bay for less money can do the job.
You find 2 familys of probes:

from dc to 225MHz the input is 1M
higher then 225MHz, this are 50 ohm systems, not useful for audio.
Some fast scopes can switch between them, they have both inputs.

greetings
Martin

 

[I LIKE MUSIC]

With a 100MHz scope not sure why you'd pay extra for 150 or 300MHz probes? Won't hurt as long as the capacitance are compatible, but don't believe there is any practical benefit otherwise.

Remember that when it comes to oscilloscope probes, is is not uncommon for the rated frequency response to be the 3dB down point.



For audio frequencies it is likely not to make a lot of difference in this case.

For RF frequencies (such as found in an FM tuner front end), a 10 volt 100 MHz signal would be down by 3 dB, about 3 volts (It would read about 7 volts instead of 10 volts) with a 100 MHz rated probe, just to use round numbers as an example.

My OCDness tends to bias me towards quality oscilloscope probes rated at about twice the oscilloscope's rating.

Switchable attenuation (1:1 and 10:1) is handy to have, although the bandwidth will be limited on 1:1 attenuation.

 

[dbxdx5]

I just found the specs of the original Tektronix probes that came with this model:

2 meters
10x
100MHz
13pF
10Mohm

So go with probes that are 200MHz but otherwise have similar specs for capacitance and resistance?

EDIT: The capacitance of these are a little higher, but would that make much of a difference? The 2336 specifies <15pF and these Hantek probes compensate down to 15pF.

UPDATE: I ordered them.

 

[gadget73]

I'll be honest with you, for years I've been running cheap as chips switchable 10x 100mhz probes from China via ebay. They come in a 2 pack for like 20 bucks. I did finally break one by running it over with my chair and bought two more. My scope only runs up to 40mhz though, so those probes are more than adequate. Also, considering the vast bulk of what I do is audio frequency, it wouldn't matter even if the scope were rated beyond 100mhz.

 

[dbxdx5]

I'll be honest with you, for years I've been running cheap as chips switchable 10x 100mhz probes from China via ebay. They come in a 2 pack for like 20 bucks. I did finally break one by running it over with my chair and bought two more. My scope only runs up to 40mhz though, so those probes are more than adequate. Also, considering the vast bulk of what I do is audio frequency, it wouldn't matter even if the scope were rated beyond 100mhz.

Good to know, since that's not much less than what I just paid for the Hantek set. Gotta love that Amazon Prime free shipping.

 

[Brickbat]

Those cheap 'P6100' style probes are fine. They're all over eBay for $10 a pair! For the money, you can't go wrong.

It's also nice to have some BNC cables, with clip leads on the other end, and some that go to RCA and even 3.5 mm. Sometimes probes are a pain.

BTW - great avatar - Best songwriter alive, IMHO...

 

[dbxdx5]

Good suggestion about the non-probe options to keep around. Thanks.

Agree wholeheartedly on VM!

 

[blhagstrom]

I'll be honest with you, for years I've been running cheap as chips switchable 10x 100mhz probes from China via ebay. They come in a 2 pack for like 20 bucks. I did finally break one by running it over with my chair and bought two more. My scope only runs up to 40mhz though, so those probes are more than adequate. Also, considering the vast bulk of what I do is audio frequency, it wouldn't matter even if the scope were rated beyond 100mhz.

+1

For general audio repair, any damn thing that can trace a signal works fine.

I don't do much tuner repair, and no alignment so even cheap scopes work for most of the things I have time to do.

My spendy high end scope gets pretty dusty between uses.

O-scopes seem intimidating and people think they need to be brilliant and use them to the full potential.
The basic use is simple and for general vintage gear work, their use is easy.
The best thing to know and set up is an octopus system with a dual trace scope.
You can find and fix stuff pretty quick with a rig like that.


Now, that's not to say good high end scope use and skill is not respectable.

 

[gadget73]

I use mine as a signal tracer as much as anything else. Signal in on channel 1, signal out on channel 2, see if they look basically the same or if its getting mangled in the middle. Move the probes towards each other until they end up on opposite sides of the bad part.

It can also be useful just as a visual indicator of whats going on. Sine wave in, something that isn't a sine wave out means its not working right. The particular units don't always matter all that much, and most of the time I don't pay any mind to what mine is actually set to. I turn the knobs until the picture shows me what I need to see.

 

[BinaryMike]

High quality probes generally yield superior fidelity on fast signal edges, which can be a very big deal in digital circuits. And the performance you're paying for occurs only with minimum-length probe ground connections. The audio world outside our little enclave has gone digital, so this matters to a lot of folks. Also consider that shorter probe cables yield reduced probe tip capacitance, almost independently of compensation range. Probe tip C can be a big issue when probing high-impedance nodes in tube or SS amplifiers, especially if your calling is circuit design, but it doesn't hurt to minimize this influence even for troubleshooting purposes.

 

[efzauner]

For audio testing I usually just use bnc to aligator clip cables. The probes are really only needed for MHz range and compensating the inductance. Sure 10-1 is good for higher voltages...

 

[gadget73]

the 10x attenuation is about 90% of why I use them. The rest is price and the hook end that works to grab on component leads. Could be done with an in-line 10db pad and a set of minigrabbers though.