[ARC5] AM linear amplification

[AKLDGUY .]

On Tue, Dec 20, 2016 at 5:37 PM, Richard Knoppow <1oldlens1 at ix.netcom.com>
wrote:

>    After a little though. The triode connection is somewhat unusual since
> normally one would see the screen connected to the plate rather than to the
> control grid. BTW, the RCA HB-3 tube handbook shows curves for a triode
> connected 807 but does not specify the connection (or perhaps I missed it).
> A casual inspection suggests its pretty linear but the curves may be
> different for the screen and control grid being tied together. This is a
> very intriguing idea.
>
   I will add just a little more. A controlled carrier transmitter varies
> the carrier so that the signal is essentially always modulated 100% but the
> entire envelope varies with the modulation level. Usually there is a
> residual carrier at some fairly low level. The idea is that a linear
> amplifier will work about the same as it does for an SSB signal and does
> not need to dissipate the carrier power continuously.  The requirement for
> _peak_ power is not changed but the _average_ is substantially reduced.
> There are commercial transmitters that put out controlled carrier AM such
> as the Drake T-4B and C. This is meant to allow them to be used with a
> standard SSB linear without having to cut the power way down. In receiving
> one needs either the same sort of fast attack, slow release AVC used for
> SSB or manual RF gain if the audio is not to "pump". I think there is
> probably a lot of material in the literature for controlled carrier systems.



A residual carrier at low level? I thought the drive was set much higher
than that, so that a substantial carrier was transmitted even with no
audio. This points up the lack of good articles in the literature on the
adjustment of high level AM linears that I mentioned in my first post.

73 de Neil ZL1ANM
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