Harmonics.

I was on 40m when OH8STN sent Heartbeat message from few kilometers away. It was overwhelming my RX and I managed to catch a screenshot.

His message was sent on frequency 889Hz, but we can also see signal harmonic on 1778Hz (2 * 889Hz) and 2667Hz (3 * 889Hz).

Also notice how the width doubles on 2nd harmonic (1778Hz) and triples on 3rd harmonic (2667Hz).

Maybe this doesn't have any other point, but to show how harmonics look like on waterfall.

@oh8hub that's really interesting! I've never seen the spread so clearly shown too.

@M0YNG Indeed! It took me a while to understand what's happening. What I don't know if why is it happening.

From these little things we can learn and build our knowledge.

@oh8hub @M0YNG What once was a great weak signal mode is being destroyed by people running way too much power and improper drive levels. I cringe when I see Eb/N0 numbers like +25dB while stations copy my -25 dB QRPp. My best was Japan on 15 meters with 100mW

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@W8HF @M0YNG This case of OH8STN signal showing harmonics on my waterfall was my fault!

I had my rig's RF gain up. Lowering gain down removed the harmonics. So this phenomenon was purely on my RX side.

This is a screenshot of me lowering the RF gain in middle of heartbeat transmission. See how the harmonics just disappear while original signal still continues on it's frequency.

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@oh8hub @M0YNG Awesome. I meant to follow up and ask about your audio level into your interface. You can also get harmonics like that if you start to overload your audio interface.

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