[Elecraft] K3 and Expert 1K-FA

[Wes Stewart]

Yes.  In fact since with the except of a few newer radios 100W seems to be the "standard" it seems to me that amplifier suppliers should build amps to that standard.

If they have enough gain to deliver rated power with only 50 W in, then put a 3 dB pad inside.  There are additional benefits to this, including a more uniform match for the exciter (possibly lowering IMD) and a better defined source match for the amplifier (possibly lowering IMD).

In fact, it can be argued that the ALC should be internal to the amplifier, rather than depending on some unknown loop characteristics in the exciter.  Imagine a receiver designer trying to design an AGC loop when he doesn't know the characteristics of the gain-controlled stage(s).

Seems to me that some combination of fixed attenuation, some PIN diodes and active control of the device bias would solve a lot of operational issues.

Wes  N7WS

--- On Wed, 4/21/10, Alan Bloom <n1al at cds1.net> wrote:


> On Wed, 2010-04-21 at 12:23 -0400,
> Tom W8JI wrote:
> 
> > The correct approach would be an 
> > attenuator pad so the radio could run at near full
> power and 
> > not have a chance of overdriving the amp, ...
> 
> I don't understand why more people don't do that.  For
> example, a 3 dB
> attenuator between the transceiver and amplifier ensures
> that a 100W
> exciter won't overdrive an amplifier that requires 50W of
> drive.  The 3
> dB loss on receive is hardly ever an issue but if you're
> worried about
> it, just put the attenuator inside the amplifier, after the
> T/R relay.
> 
> Seems like a simple, foolproof solution.
> 
> Al N1AL