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Oscilloscope?

K

KK4JW

Active Member
May 18, 2022
43
39
28
Kentucky
I've never owned a 'scope until now, and I'd like to use it to help with alignments and audio adjustments on my personal equipment. I am a big stickler for clean audio, so I felt it was time to invest in a piece of equipment that I could use to help me achieve that.

As I've never owned a 'scope until now, I've also never used one, so I don't know what I am doing. I do understand that it's a no-no to feed RF straight into the input of the 'scope, so I'll need to fashion an RF sampler of sorts. I'm considering wrapping a few turns of wire around my dummy load and clipping the test lead to the ends. I'd imagine there should be enough coupling there to get a usable RF sample.

Other than that, I'm flying blind. This thing has several buttons and knobs - I have no idea what they do. The included manual is poor ching-lish.

This is the model I purchased. Don't laugh. It's not a Tek, but it was inexpensive and better than the one I had before, which is not one. Amazon product ASIN B0833YFNKP
Are there any special settings I need to configure before I start using it to measure audio and carrier waveforms? What else can I use this thing for other than that? Thanks!
 
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These might help with the very "basics" of scope utilization. They might help give you an idea what they are for to give you an understanding.

This guy has a channel "Uncle Doug". He actually does tube guitar amplifier repair videos... but he put up these two to introduce his viewers to the use of scopes.
I hope it helps!

1 of 2

2 of 2

One basic word of caution.........
Most more modern scopes use a three prong plug and DO have a safety ground pin. The little ground clip that hangs off of the probe... is USUALLY connected to that ground in the scope! You have to be very careful just WHERE you clip that ground probe in your "radio under test". If your radio happens to have a safety ground reference (either through it's own 3 prong plug or through the shielding of a coax cable connected to another piece of test equipment)... and you clip thatground probe .... willy nilly in the circuit you are testing..... you can let out what we call "the magic smoke". You could be clipping it to a point that is actually a DC voltage supply or reference point and "grounding" it.... which can cause severeproblems. Ask me how I know! I'll tell you about my JC Penney Pinto!

Itis NOT that you have to be afraid..... just have to be careful.

Good luck in familiarizing yourself with that scope...
 
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guitar_199 said:
These might help with the very "basics" of scope utilization. They might help give you an idea what they are for to give you an understanding.

This guy has a channel "Uncle Doug". He actually does tube guitar amplifier repair videos... but he put up these two to introduce his viewers to the use of scopes.
I hope it helps!

1 of 2

2 of 2

One basic word of caution.........
Most more modern scopes use a three prong plug and DO have a safety ground pin. The little ground clip that hangs off of the probe... is USUALLY connected to that ground in the scope! You have to be very careful just WHERE you clip that ground probe in your "radio under test". If your radio happens to have a safety ground reference (either through it's own 3 prong plug or through the shielding of a coax cable connected to another piece of test equipment)... and you clip thatground probe .... willy nilly in the circuit you are testing..... you can let out what we call "the magic smoke". You could be clipping it to a point that is actually a DC voltage supply or reference point and "grounding" it.... which can cause severeproblems. Ask me how I know! I'll tell you about my JC Penney Pinto!

Itis NOT that you have to be afraid..... just have to be careful.

Good luck in familiarizing yourself with that scope...
Click to expand...


Thank you! Also thanks for the video links. I'll be sure to check those out! Is there a widely accepted "safe place" to clip that ground clip on the test lead? I was thinking perhaps the radio chassis?
 
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KK4JW said:
Thank you! Also thanks for the video links. I'll be sure to check those out!
Click to expand...
Just after finishing this posting.... I came out and saw thatyou posted a link to the type of scope you have. Note... yours may not be the exact same scope that Doug is using..... but the controls of a scope are similar in nature from one scope to another. So hopefully you can follow Doug's videos.... then looking at your own scope... find it's controls for the same functions!
 
Just watched the first video, and it is excellent IMO. Really de-mystified the settings and helped me to understand volts per division. I'm wondering though, is there a proper "volts per division" setting to use when looking at a RF waveform? Or do I just basically want to fiddle with it until I can get a picture of everything?

I imagine the volts per division setting wouldn't be a finite number, as there would be varying carrier levels, etc, affecting the amount of voltage that the probe sees.
 
KK4JW said:
Just watched the first video, and it is excellent IMO. Really de-mystified the settings and helped me to understand volts per division. I'm wondering though, is there a proper "volts per division" setting to use when looking at a RF waveform? Or do I just basically want to fiddle with it until I can get a picture of everything?

I imagine the volts per division setting wouldn't be a finite number, as there would be varying carrier levels, etc, affecting the amount of voltage that the probe sees.
Click to expand...

"Or do I just basically want to fiddle with it until I can get a picture of everything?"

at least "initially" ... that is what I do. Rattle that selector around till I can see it.
 
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remember that a scope is a voltmeter and you are not 'feeding RF into it' when you connect it's probe to a circuit.

you can put that probe right into a wall socket and measure the sinewave of your home AC power.

i regularly use my scope to calibrate wattmeters for people and for myself.
this involves clipping the probe right to the center pin of the coax.

you do need to have an idea of how many AC volts your RF wattage equates to just to make sure you don't try to measure more voltage than the scope is rated for, just like with any other voltmeter.
LC
 
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loosecannon said:
remember that a scope is a voltmeter and you are not 'feeding RF into it' when you connect it's probe to a circuit.

you can put that probe right into a wall socket and measure the sinewave of your home AC power.

i regularly use my scope to calibrate wattmeters for people and for myself.
this involves clipping the probe right to the center pin of the coax.

you do need to have an idea of how many AC volts your RF wattage equates to just to make sure you don't try to measure more voltage than the scope is rated for, just like with any other voltmeter.
LC
Click to expand...
LC, this is going to make you think I am an idiot......

You said something about calibrating power meters using your scope.......

Does that old E squared over R work? I mean... if you take the peak to peak and convert it to RMS and divide by 50.... ... does that hold up for this purpose????

Thanks!
 
KK4JW said:
I've never owned a 'scope until now, and I'd like to use it to help with alignments and audio adjustments on my personal equipment. I am a big stickler for clean audio, so I felt it was time to invest in a piece of equipment that I could use to help me achieve that.

As I've never owned a 'scope until now, I've also never used one, so I don't know what I am doing. I do understand that it's a no-no to feed RF straight into the input of the 'scope, so I'll need to fashion an RF sampler of sorts. I'm considering wrapping a few turns of wire around my dummy load and clipping the test lead to the ends. I'd imagine there should be enough coupling there to get a usable RF sample.

Other than that, I'm flying blind. This thing has several buttons and knobs - I have no idea what they do. The included manual is poor ching-lish.

This is the model I purchased. Don't laugh. It's not a Tek, but it was inexpensive and better than the one I had before, which is not one. Amazon product ASIN B0833YFNKP
Are there any special settings I need to configure before I start using it to measure audio and carrier waveforms? What else can I use this thing for other than that? Thanks!
Click to expand...
I've been eyballing this scope for part of the afternoon.
I really think you are going to like it.
I am recommending it to a friend.
 

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