>> ** The grid does not and can not draw current when a competent
>>operator........
>
>Oh yes it can....! If you can show me a transceiver with an ALC loop which
>doesn't transiently produce output spikes significantly in excess of the
>steady-state level, then I'd be prepared to believe that control theory is a
>form of magic.
** All transceivers overshoot. A competent operator knows to Not
tune up a Class AB1 amplifier for SSB use with AØ/NØN/"hammer-down"
because the peak output V will not be developed from the driver with
AØ... . Instead, he/she uses a tuning pulser so that the true peak
output potential is fed to the grid. Thus, when the DC grid bias
potential is subsequently set for zero grid-I, there will be none during
actual operation.
>
>A competent operator can certainly set-up the output of a transceiver to
>keep out of indicated grid current in the steady state, but in the real
>world with typical ssb transmitters, that's a highly simplistic view.
>
** Competent operators do not have a simplistic view. They know that
the DC grid bias potential needs to be set so that there is no
grid-current under maximal peak (not AØ) drive conditions. Once the grid
is set for 0-current, if needed, the ZSAC can be tweaked with the
screen-V adjustment. However, this process is simpler if a transceiver
with front-panel power-adjust is being used.
>For excellent linearity, a tetrode linear amplifier of any size really does
>need stable, low impedance supplies for G1 and G2.
** For G2 in Class AB1, undoubtedly. For G2 and G1 in Class AB2, yea
verily, but not for G1 in AB1.
>It doesn't need a higher
>degree in thermionic electronics to understand why. In a class-AB1 tube
>amplifier, the dc currents flowing in both the G1 and G2 circuits are
>powerful diagnostic tools, providing the supply voltages are stable.
>
** There is no more than Zero DC G1 current in a thermionic Class AB1
amplifier.
>Just because Collins used a number of short-cuts in their transmitter
>designs of the the '50s and '60s, it doesn't necessarily mean that we should
>follow their practices slavishly half a century on. It's now possible to
>make good G1 and G2 power supplies for a few tens of euros/dollars, and
>these have effctively obsoleted earlier practice.
>...
>Chris
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