I have been using a YXM modified design
PA for years and todate no FETs zapped. I use 4 fets and run up to 800W out and
have been higher but my PSU is the limiting factor. I use around 18 volts key
down, solid PSU transformer. The current is heavy but not a problem, no ringing,
I also have 2 Decca Jeeps (5501) they also run cool
but I prefer to use my home built system. I have used old TV line
cores to see what difference it makes and they work just as well as the
I prefer normal CW but have used QRS 60 by request
for transatlantic, the FET'S and the LPF components run cool, barely
warm. I do use a fan on the PA and another
on the LPF.
Cannot understand why so many are having problems.
I do make a point of having the antenna properly
resonant and matched on the required frequency. My antenna base
loading inductor is around 0.3 mH for the Vertical.
There is a trick about how to wind the PA
transformer, it seems I am the only one that knows about it, although having
tried the conventional way it worked fine.
73 de G3KEV