[Amps] (no subject)

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Sun, 28 Mar 2010 06:04:53 -0700, "Jim Thomson" <Jim.thom at 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