Another Oscope question.

[Koolaide]

First, I want to say thanks all here for the help with the scope and IT questions. Best damn amp forum on the planet. Thank you all.

Now on with more rookie questions.
I got my replacement scope this week Protek 6502. I sure ain't no Tektronic's, but hey for less than a C note, all in...
I went to calibrate and it with the onboard square wave generator, (1Mkz@ .5v) and there are no visible vertical parts of the wave. Is this normal?

I went to connect my old audio signal generator, and it doesn't appear to be working. This brings up my next question.
What do you guys use or recommend for a signal generator for tube amp work? Think cheap but good I'm about busted after the scope and a isolation transformer on the way.

All replies are appreciated.

[pompeiisneaks]

I don't know that scope, but there's a chance your scope's resolution on time base is a bit 'meh'. You can zoom the time base in/out and make the tops of the square wave much longer and see if it appears at that point?

As for signal gen, I have an HP I got from a forum member that was broken and with sluckey's help I repaired it. Before that, though, I was just using my phone with a signal generator app into the amp input. No problems there, I've had people on FB tell me that I'm risking destroying my phone instead of buying some cheap device for 20$ from china, but I never had issues. I don't see how anything on an input would be dangerous, unless you miswired the amp, and usually with a signal generator, I'm using it on a known good amp, not a new build...

at any rate... there are plenty of options. Just like the one you guy there are quite a few inexpensive signal generators on ebay or amazon for pretty cheap.

~Phil

[sluckey]

Several reasons to only see a flat line on that scope. Probably just operator error. Post a pic that clearly shows the display and all knob/switch settings and maybe we can figure it out. BTW, that cal output is really only used to adjust probe compensation, although you can view it with just a gator clip test lead. Should see a .5V pp square wave when scope knobs/switches are set to the correct position.

I use a Hewlett Packard 204D oscillator. You can find them for about $50 if you are patient and don't mind cleaning switches and pots.

[Koolaide]

Here are photos-

seller screen photo.jpg

20200329_150034.jpg

20200329_145923.jpg

20200329_145900.jpg

[Phil_S]

If you have an old computer lying around, you can download a sig gen program and run the tone out from the audio. You may need to build a cable for it -- couple of snips and a bit of solder should do the job so you have the right connectors at each end. This is about as almost free as it gets.

[sluckey]

Are those your photos? I see a .4Vpp square wave in the second pic. I have no idea what the scope input is connected to.

[Koolaide]

Photos in prior post are of calibration from scope .5v is all it says. I assume .5pp- I removed the probe to show settings clearly
I do not know source or settings for photos below, but this one is from listing showing trace.

s-l500.jpg

[xtian]

For sig gen, I use an inexpensive model: FG-100 DDS FUNCTION GENERATOR from eBay. Works good. I only ever use sine waves.

[sluckey]

The center pic you posted above looks like the cal output of the scope. The other two pics look like what you would see with the probe connected to nothing.

The owner's manual is online.

[Koolaide]

The center pic is the only one showing trace. The other two were only taken to show settings. So am I correct in understanding the reason there are no vertical lines on the trace is because I am using calibration for signal? I have downloaded the manual, but thanks for letting me know in case I had not.

Thanks

[martin manning]

So am I correct in understanding the reason there are no vertical lines on the trace is because I am using calibration for signal?

No, it's there, and that will happen with any square wave. The beam spends such a short time on that part of the waveform that the phosphor doesn't glow very brightly.