Way back when (when disco was new..) I worked in a 2-way shop, and I was
able to get up to 5W out of the new (at that time) 4W rigs. Done right,
it's a marginal if mostly un-noticable improvement. Done wrong, the harmonic
output goes way up, the output transistors get hotter than they should, and
it's just a mess.

Spend the same money on the antenna!

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KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR