[ARC5] Lopsided modulation

[Tom Lee]

The maximum slope occurs around the peak, so the worst case would be for 
the resonant peak to align with one sideband.

Tom

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Prof. Thomas H. Lee
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On 2/27/2018 11:35 AM, Richard Knoppow wrote:
>    I would add, as I did in a previous post, that a _loaded_ final 
> tank has rather low effective Q. It is desirable in most cases to 
> maximize the Q of an _unloaded_ tank but when connected to a load the 
> load impedance is imposed on the tank. That is why the dip in plate 
> current at resonance becomes less as the loading is increased. At some 
> point the plate resonance can be see more easily as an increase in 
> power. If the amplifier is properly neutralized this peak should be 
> coincident with the dip in current and can be easier to see when the 
> load is near optimum.
>    I suppose a tank with low loading and mis tuned for the dip could 
> be far enough off resonance and maybe sharp enough to reduce one 
> sideband but I think it would have other problems at that point.
>
> On 2/27/2018 11:27 AM, Tom Lee wrote:
>> Yes, the muddle is very odd. Bob said it succinctly and correctly: 
>> The shape of the modulation spectrum has no impact on symmetry of the 
>> sidebands. For pure AM or pure FM, you get symmetrical sidebands, 
>> period. As a professor, I leave it as an exercise to the student to 
>> compute how high a tank Q would be necessary to produce a pronounced 
>> asymmetry (hint: you will find it hard to contrive sensible numbers 
>> in most cases). By far the most common source is the simultaneous 
>> occurrence of AM and FM. It is difficult to build a 
>> modulator/transmitter chain that is completely free of incidental 
>> modulation by the unwanted mode.
>>
>> Cheers
>> Tom
>>
>