Need some Scope probe advise.

[Brian Deese]

My new scope came in today,I was setting it up and the procedure was to set the controls to certain positions then hook the probe to the test terminal and adjust the pot inside the probe until the square wave was not distorted.The probes are poor quality in my opinion,they have a slider switch for x1-ref-x10 so I adjusted them,but I am not confident they will stay that way.You get a slightly different wave shape when you use the clip on accessory also.If you bump the switch with your finger you can see it in the trace,just doesnt inspire confidence.Would a non switchable 10x quality probe be a smart investment? Or should I buy a quality switchable x1-x10 probe? And the other question is my scope is a 20mhz so do I have to buy 20mhz probes? Or is that just the minimum and say a 60mhz probe will work fine? I dont quite understand the bandwidth spec yet.Thanks

[SVEN1]

I just picked up my first scope, 40mhz, without probes and made a posting on the TEK yahoo group site about probes. For our low mhz units we don't need fancy expensive probes.
They all recommended these probes which they had good luck with:
Look at #'s 8-9-10
http://s.dealextreme.com/search/probe

Here's some good tutorials:
http://www.youtube.com/watch?v=qIfo_-d82Co

http://www.doctronics.co.uk/scope.htm

Hope this is of some help to you

[6666]

I bought two 1x10x colour coded probes with spring clips and all connectors for $4.00 posted from china on fleabay,
they work great , try a search on fleabay.

[Brian Deese]

Probes

I bought a Tek probe on ebay yesterday I think I will like it better.Thanks for the tutorials that was very helpful,answered a couple questions I had.I do have another question.When I look at the square wave on the scope the vertical elements of the square wave are very thin,so thin you really cant see them.I have seen scope pics(on this forum I think) that look the same,so it is probably normal but I was curious.I have also seen scope pics where the vertical lines looked just like the horizontal ones.

[Carl-NC]

On a CRT scope the vertical lines on a fast edge will be thin, that's normal. On an LCD scope they will be the same as a horizontal line.

I wouldn't trust cheap Chinese probes for 100MHz work, but for metal detectors they're fine.

[Brian Deese]

Thanks Carl

On a CRT scope the vertical lines on a fast edge will be thin, that's normal. On an LCD scope they will be the same as a horizontal line.

I wouldn't trust cheap Chinese probes for 100MHz work, but for metal detectors they're fine.

Yeah one of the probes that came with the machine will not compensate completely, square wave has a ramp on the corner.I will pick up some good probes no problem.Well it is my first scope and it wasnt alot of money, and it is new old stock never used.Maybe I will upgrade after I master the controls.I probed that af-108 with the scope yesterday,looked at every test pin,saw what every pot adjusted.I adjusted it every which way there was no performance gain.The waveform on the output of the preamp looks different from what I have seen.Of course its bipolar and there are pos and negative pulses.I need a better understanding of the 4066.I think it samples the pos and neg going signal after the flyback decays and compares,integrates or what ever it does those two.Kinda makes sense to me because when you bring a target in the pos goes higher and the neg goes lower.Anyway its a boiled turd,I plan to start a hammerhead very soon.