Siglent P510 Probes - Junk or bad luck ?

[BillyO]

The wavelength of 20 MHz is about 50 meters, so about 35 meters in coax.  As long as you use your 20 MHz BW limiter, there won't be any transmission line effects.  You still can pick up noise below that with loops in the test leads, etc, but that isn't related to any impedance or transmission line effects.

I'm in agreement here.

I wouldn't use any 1X probe with a 50R input setting, or am I misunderstanding you?

Perhaps.  I was referring to straight coax cables with (or without) alligator clips, not 1X/10X probes set to the 1X position.

[bdunham7]

Perhaps.  I was referring to straight coax cables with (or without) alligator clips, not 1X/10X probes set to the 1X position.

OK, so if it is a coax with BNCs on each end and your source is 50R, that's one thing.  But I'm referring to using some sort of relatively plain wiring (whether or not coax is involved anywhere) to connect your scope to some low-frequency (<5MHz) circuit.  That's a 1X probe of sorts and you would just use the scope with a 1M input, assuming you even have a choice.

[BillyO]

OK, so if it is a coax with BNCs on each end and your source is 50R, that's one thing.  But I'm referring to using some sort of relatively plain wiring (whether or not coax is involved anywhere) to connect your scope to some low-frequency (<5MHz) circuit.  That's a 1X probe of sorts and you would just use the scope with a 1M input, assuming you even have a choice.

Sure, if frequencies are low enough you could use cab tire or microphone cable or whatever.  Not an issue.  I think we're on the same "wave length" here (really bad pun intended) that's why I said "Of course with audio frequencies it matters little".  It would equally apply to AM radio and stuff in that range, but at least proper shielding should be used for small signal situations.

Didn't really mean to start an argument.