Choosing oscilloscope probes

[I_Forgot]

Originally posted by DragonMaster
In fact I want to look for oscillation in audio circuits, align some FM tuners, and probably in a near future, start playing with Microchip PICmicros (Fortunately, both cards each have an 8-channel logic analyzer module, which means I don't "necessarily" need probes for this task, unless I start to find some trouble).

Logic analyzers, unless they are very fancy/expensive, are good when everything is clocking right. Sometimes you need a scope so you can find clock problems that you can't find with a logic analyzer. When your logic analyzer gives you garbage but the simulator tells you it should all be working, its time to break out the o-scope and start looking for glitches that shouldn't be there.

Always get as much BW as you can afford, and get probes to match. If the probe BW isn't at least as high as the scope, you're wasting capability of the scope.

I_F

[DragonMaster]

The trimmer cap is to match the probe to a particular socket.

So a 200MHz and a 100MHz per card.

Even probes without trimmers should work as the software utility allows to adjust the 'scope to the probe.

[EC8010]

All x10 probes have a trimmer. Perhaps other people have been luckier, but I've had dicky switches on switchable probes. Worse, you can accidentally switch it to GND, not notice, then waste time looking for your signal...

[DragonMaster]

Worse, you can accidentally switch it to GND, not notice, then waste time looking for your signal...

But if you get used to them it might be different.

[unclejed613]

actually you don't need a wideband probe or scope to align fm receivers. you use a frequency modulated rf generator and an rf "sniffer" probe which consists of a pair of low capacitance diodes, a resistor and a couple of 100pf caps in a voltage multiplier arrangement. the output of the probe goes to the scope vertical, and the modulating voltage (sine wave or triangle wave) goes to the rf generator and the scope horizontal input with the scope in "XY" mode. the rf generator should be set up to provide about 200khz deviation. with the probe at the mixer input, you align the rf stages, and with the probe at the detector input you align the if stages. the scope gives you a response curve with the center frequency in the middle, and +/-100 khz at the edges.

[jarthel]

any chance of providing a link to the auction you won?

thank you.

[DragonMaster]

eBay 330105968878 & 330110203129

one of them fails a self-test so maybe I'll use 1 scope of the two, requiring only 2 probes.