Quote:
Originally Posted by ukcol
Quote:
Originally Posted by Skywave
In a phrase, cumulative frequency-sensitive attenuation.
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Does this mean the -3dB point becomes -6dB overall. |
Basically, yes (that's assuming that the two are connected in cascade, there's no parasitic feedback around the whole thing, etc etc).
So the 3db points would be somewhat narrower. How much narrower depends on the shape of the response curves of the original IFT's. If these were ideal, square-topped, brick-wall responses, there wouldn't be any narrowing at all!
Quote:
Originally Posted by G8HQP Dave
The infinite impedance detector is nearer to being an ideal envelope detector than a diode detector, but it still suffers from the limitations of an ideal envelope detector. It still can't do negative peaks at 100% modulation.
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True, but it could get there more nearly. And it doesn't have the limitations of AC/DC load ratio of less than 1, causing a limit to amplitude modulation depth without distortion.
It's also worth considering, a HF push-pull input, maybe a double-triode with cathodes strapped together. That would allow a halving of the cathode capacitor value for the same degree of HF ripple, so the audio frequency at which non-linear distortion started to kick in would be doubled.