Which scope should i buy ?

[tepsamps]

Hello,
so far i did not feel the need of having a scope to repair or tune an amp. Now i would like one because i can't find out an issue on a build i've made some time ago.

Digital one or analogic one ? The old analogic are cheap on bargain market, just the probes are missing, but the probe seem to be expensive. The cheapest digital scopes are maybe crappy...

Have you got an advise for me ?

[Mick Bailey]

Digital scopes are fine but you must be certain that the maximum input voltage is never exceeded. One slip or mistake can cause damage. I like the CRT analog Tektronix scopes for this reason - they have a good deal of resilience even when overloaded. It's really easy to be poking around and not notice your probe is set to x1 instead of x10. This is where perhaps an external scaling box is useful and one that has protection against high voltage and DC - especially if you're using a digital scope. Do a search here and find the one designed by Juan Manuel Fahey.

[alexradium]

CRT all the way.
Good digital scopes start over 300.

[loudthud]

You want a real professional level scope, not a toy or hobby scope. A real scope will have:

BNC connector for the input.
Input will be marked 1 Megohm and an input capacitance usually between 15uF and 50uF.
There will be some kind of signal on the front marked "Probe Calibration". Usually a 1KHz square wave.

Many used scopes are broken in some way. There is much more to a scope than making a bright line across the screen. If the seller doesn't know how to operate the scope or says "No time to test", don't buy. Only buy from someone who will guarantee the scope works or will take it back if it doesn't.

Cheap probes are OK, but high Voltage will kill them. An X1 or X1-X10 probe is probably crap. Stick with X10 or X100.

The better the scope you buy, the better you will become at making or fixing amps. A poor scope will hold you back.

[nosaj]

Hello,
so far i did not feel the need of having a scope to repair or tune an amp. Now i would like one because i can't find out an issue on a build i've made some time ago.

Digital one or analogic one ? The old analogic are cheap on bargain market, just the probes are missing, but the probe seem to be expensive. The cheapest digital scopes are maybe crappy...

Have you got an advise for me ?

What is your location. There is a guy local to me that sells digital scopes I got an hp54602b for a 140 from him. Calibration sticker. Now problems at all with it. If you interested I'll contact him an see if I can forward his info.

nosaj

[Chuck H]

I got my last one (BK 2522A dual trace) on *bay over a decade ago from a seller stating that it was tested and fully functional. It came with a clip probe, a 10x switch probe and manual. I remember paying something like $237.00 shipped. Never had a problem with it. I think it's important to buy from a seller that can state that the unit has been tested or refurbished because, as mentioned, there can be problems with a used 'anything' if it's sold as "not tested", "as is", "we don't know how to fully test", "light comes on", etc. Example from one auction I looked at:

...has been tested for basic functionality. Unfortunately, we may or may not have the equipment and knowledge to fully test/calibrate certain units in-depth...

I'd be concerned that this seller might even be aware that the thing is busted and doesn't want to say it.

It takes more time and reduces selection to find an auction that gives you confidence but it usually won't cost much more and I'd never do it any other way.

Here's a Tenma listed as "lightly used" and "every function works fine" with two 10x probes from a seller with 456 transactions and 100% positive feedback. Tenma has a decent rep for a less expensive brand. I'd probably consider this scope an option at only $127.80 shipped.

https://www.ebay.com/itm/Tenma-72-68...dTGOd&LH_BIN=1

And here's an HP for $227.00 shipped that says it's tested and calibrated (as far as self calibration goes I guess) and the seller sounds like they know what they're selling, has 2157 transactions and 99.8% positive feedback.

https://www.ebay.com/itm/HP-Agilent-...dVIBS&LH_BIN=1

And don't forget that if you don't already have a signal generator and a dummy load (and I don't know why you would without a scope) you'll need to make arrangements for those items also. Which is why, though considered a lesser brand by many, one might consider the Tenma scope for it's lower price tag. Especially since as guitar amp tweakers/builders the scope is only going to be lightly used. This would leave you with more budget for the other necessary tools.

[nosaj]

I got my last one (BK 2522A dual trace) on *bay over a decade ago from a seller stating that it was tested and fully functional. It came with a clip probe, a 10x switch probe and manual. I remember paying something like $237.00 shipped. Never had a problem with it. I think it's important to buy from a seller that can state that the unit has been tested or refurbished because, as mentioned, there can be problems with a used 'anything' if it's sold as "not tested", "as is", "we don't know how to fully test", "light comes on" or etc. It takes more time and reduces selection to find a unit like this, but it usually won't cost much more and I'd never do it any other way. At the going price for used scopes I never worry much about having to replace it either.

Here's a Tenma listed as "lightly used" and "every function works fine". from a seller with 456 transactions and 100% positive feedback. Tenma has a decent rep for a less expensive brand. I'd probably consider this scope an option at only $127.80 shipped.

https://www.ebay.com/itm/Tenma-72-68...dTGOd&LH_BIN=1

And here's an HP for $227.00 shipped that says it's tested and calibrated (as far as self calibration goes I guess) and the seller sounds like they know what they're selling, has 2157 transactions and 99.8% positive feedback.

https://www.ebay.com/itm/HP-Agilent-...dVIBS&LH_BIN=1

I pretty much have both those scopes, started with the tenma for $85 local I liked that it had a function generator with it when I started(not the best but it got the job done.
Playing with it I would run function into ch1 so I could play with the signal and get a feel for how the controls worked(much better than learning on an amp). Mine also has a ch1 output which I put a .01 630 volt cap on into an audio cord and into a test amplifier, instant signal tracer audio/visual. As of now that is all it gets used for now.
The hp has voltage and frequency displays for the channels Which removes another needed device(provided your careful and aware of what your measuring if your doing SMPS or tube equipment.

My experience with both those scopes has been great. My hp the only difference is that's its 4 ch.

nosaj

[nosaj]

I pretty much have both those scopes, started with the tenma for $85 local I liked that it had a function generator with it when I started(not the best but it got the job done.
Playing with it I would run function into ch1 so I could play with the signal and get a feel for how the controls worked(much better than learning on an amp). Mine also has a ch1 output which I put a .01 630 volt cap on into an audio cord and into a test amplifier, instant signal tracer audio/visual. As of now that is all it gets used for now.
The hp has voltage and frequency displays for the channels Which removes another needed device(provided your careful and aware of what your measuring if your doing SMPS or tube equipment.

My experience with both those scopes has been great. My hp the only difference is that's its 4 ch.

nosaj

Buying QUALITY probes cannot be stressed enough. I started with some ebay chinese ones that were iffy. Quality probes give you one less thing to throw you off.
nosaj

[Chuck H]

I couldn't find much info on the actual usefulness of the Tenma's function generator (not even in the manual) so I don't know the actual signal voltage range it's capable of. I don't think I'd be satisfied with options of 10k, 1k or 100Hz either so I just assumed a proper signal generator would be desirable.

[nosaj]

I couldn't find much info on the actual usefulness of the Tenma's function generator (not even in the manual) so I don't know the actual signal voltage range it's capable of. I don't think I'd be satisfied with options of 10k, 1k or 100Hz either so I just assumed a proper signal generator would be desirable.

Mine has a knob where you can vary the frequency and amplitude, the buttons just are a range. It was always enough to get it done. Now radio work different story.
nosaj

[tepsamps]

What is your location. There is a guy local to me that sells digital scopes I got an hp54602b for a 140 from him. Calibration sticker. Now problems at all with it. If you interested I'll contact him an see if I can forward his info.

nosaj

I'm from europe, france. Thanks though...

[Chuck H]

I'm from europe, france. Thanks though...

This and occasional language barriers are why it's best to include your location in your membership info. I don't know if there's a note about this to new members, but I'll look into it.

The same auction criteria I outlined above would also apply to Europe of course. No "as is", "good cosmetic condition" or "we don't know how to test". Just sellers that say the unit is in good working order. And preferably sellers that have good feedback and seem to know what an oscilloscope is

[tepsamps]

This and occasional language barriers are why it's best to include your location in your membership info. I don't know if there's a note about this to new members, but I'll look into it.

The same auction criteria I outlined above would also apply to Europe of course. No "as is", "good cosmetic condition" or "we don't know how to test". Just sellers that say the unit is in good working order. And preferably sellers that have good feedback and seem to know what an oscilloscope is

I found one for 45 € that works, 2 channels 20 Mhz. I will go for a glance...

[catalin gramada]

I am hobbyist newbie,so I cannot recommend any of them. But be aware what and where You buy if go to SH. I bought till now 3 old respectable eighties Philips, all ended soon with something blowed inside followed with lot of smoke. Could be a simple job to fix it ( pretty sure there are some old caps which need to replace) but I.m not a tech. so for me all investition was junk. I ended with a 300 bucks new digital Rigol ds1102, pretty happy with it for my basic needs. Probes are other story, need as good as can afford .

[tepsamps]

I am hobbyist newbie,so I cannot recommend any of them. But be aware what and where You buy if go to SH. I bought till now 3 old respectable eighties Philips, all ended soon with something blowed inside followed with lot of smoke. Could be a simple job to fix it ( pretty sure there are some old caps which need to replace) but I.m not a tech. so for me all investition was junk. I ended with a 300 bucks new digital Rigol ds1102, pretty happy with it for my basic needs. Probes are other story, need as good as can afford .

What is the max voltage on your rigol ? What you don't say about the probes, please?