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

[David Cutter]

T0-220 style power film resistors are fairly cheap and can easily be mounted 
on heat-sinking surfaces.

David
G3UNA


> Hm, I wonder if the KPA500 has or can have provision for this.  That
> amp can be driven to full output by 30 watts or so, IIRC.  With the K3
> (or K2), power control could be done automatically by having the amp
> tell the radio that it's active over the serial interface, but it's
> clear the KPA500 has much provision for being used with radios other
> than the K3.
>
> 73, doug
>
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.
>
>