Well I have tried 13.8V & two BS170s fort he PA section and I got to almost the south coast of UK from my QTH (JO02op)
Made a 'scop-match as I knew that the antenna was poorly matched - and found it was - very.
Fixed that & changed the impeadance matching transformer - now working at about 58R and almost no reactance (Wx dependant)
So reading Hans' modifications page decided to put together HB9ASB - surprised I had most of it in the 'junk' box.
With out the LPF the waveform was ghastly!