ORIGINAL MESSAGE:
On Sun, 28 Mar 2010 06:04:53 -0700, "Jim Thomson" <Jim.thom@telus.net>
wrote:
>
>## and yes, the output of a GG amp is 180 deg out of phase with the input.
>The 2 x are in series.
REPLY:
When the cathode is driven negative, the plate goes negative too.
Sounds like in-phase to me. If you want out-of-phase, grid drive it.
Of course, you can take the in-phase signal at the plate and run it
through any kind of network you want to reverse the phase (pi-net, !:1
balun, transformer, whatever) but the tube itself is in-phase.
Likewise, if maintaining phase was important, you could use a simple
parallel LC tank in the plate circuit and tap the coil, or use link
coupling, observing polarity.
The point is, one can not make the broad statement that a GG amp is a
phase-inverter when the phase inversion, if any, is done in the output
matching network and not in the actual tube itself.
73, Bill W6WRT
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