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THE AM BULLETIN BOARD => Technical Forum => Topic started by: ki4nr on December 18, 2021, 02:51:26 PM



Title: Carrier Shift & Modulation
Post by: ki4nr on December 18, 2021, 02:51:26 PM
Hi

I'm experimenting with a low level modulator circuit for one of my rice box's. Question on the carrier in general, If you are modulating at 100 percent with perfect symmetry does the carrier shift or is it stable in power?? If you are modulating asymmetrically over 100 percent on positives does it shift in power in that setup. I know wattmeters can respond
differently, so let say a spectrum analyzer is used.

Thanks John


Title: Re: Carrier Shift & Modulation
Post by: W7TFO on December 19, 2021, 11:29:49 AM
Carrier shift can occur due to a design defect, like a soft power supply.

It can also appear via a badly matched load, but shift is not 'part of the game' inherently.

73DG


Title: Re: Carrier Shift & Modulation
Post by: N1BCG on December 19, 2021, 05:13:24 PM
Symmetric modulation will always result in minimal carrier shift. Positive peaks over +100% will cause a positive carrier shift. Low PA grid drive or insufficient power supply current will show as negative carrier shift.
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