[Elecraft] KPA500 troubles

[mcduffie at ag0n.net]

On Tue, 20 Oct 2015 08:58:17 -0700 (MST), ok1rp wrote:

> if your KPA500 has LPF board rev. D or earlier then You will need to make
> LPF TR Switch Rework REV5 modification, Elecraft parts kit: E850607. But
> maybe there is another issue in your case.

Apparently, I missed the OP on this.  What is it about?  What vintage amp (SN?),
and what does this modification do?

Gary AG0N