[Elecraft] attenuator in amp was Re: K3 and Expert 1K-FA

[Paul Christensen]

>    I can not understand why one would want to run the K3 at 100 W rather
> than 20/30/50 Watts.   Why drive the K3 harder when driving it more 
> lightly
> should improve reliability and possibly improve linearity.   The waste of
> energy is also undesirable; the fifty watts out that is discarded probably
> costs 100 Watts of energy.

For the same concerns, I think an auto-switched pad engaged during an input 
fault is a good idea.  In the case of the SPE amp, I would not like to have 
30-watts dissipating as heat in the front end of the amp.  The 3dB pad does 
improve return loss into the amp input by the same amount.  But, the 
effective gain factor of the amp is then reduced by 3dB.

The pad may assist with improving linearity from the driving transceiver, 
but improving linearity can be accomplished with better efficiency if the 
transceiver has an internal ATU with an auto-tune function that can be 
programmed to limit the transceiver's power during the tune function.

Paul, W9AC