measures wrote:
>
> >Rich says:
> >
> >>The basic problem is that there was no way to keep the screen bypass
> >>capacitor adequately charged during voice modulation
> >
> >I don't understand. It appears to me that when there is a signal, there are
> >screen volts.
>
> Not until the screen bypass C becomes sufficiently charged. Another
> problem is keeping the screen bypass C from mostly discharging on soft
> syllables. The semi-obvious solution is to Not Allow the screen bypass C
> to discharge as long as the amplifier is in operation. This is where
> Thornley seemingly derailed
>
> > If it's a big signal, there's lots of screen volts, which you
> >need because you wants lots of plate current. If it's a small signal, the
> >peak plate current is less, so you don't need as many screen volts.
>
> In order to achieve linear amplification, current gain must be constant
> at All signal levels. Screen potential has a large effect on current
> gain. At 33% of normal screen volts, an 8171 exhibits 1/4 of normal
> current gain.
>
> > So it
> >appears that screen time constant should be short enough to follow the
> >envelope of the signal - which in the original, it was.
> >
> The result will undoubtedly be varying gain.
Seems to me that this beast will do just fine on 100% duty cycle modes:
AM, FM and SSB-SSTV, SSB-RTTY, SSB-PSK, but query it's CW and speech-SSB
performance?
What was it originally mean to do?
Ian, ZS6BTE
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