To my experience there is no need for an amplifier, even at the moste remote areas of the world Im getting a lots of spots runnig the 5351 barebone, Im using 20m band and cut the antenna to regular formula with the 95% shortening of the legs, longest spots heard is 19000km, and I have got a couple of +17000km spots whitch says some of the benefits of wspr :)??
A friend of mine that flow on the south hemisphere (mostly water) used a simple bs170 as a an amp to get a few more db:s out, se attached pic of one of his earliest trackers.
/Mikael
