[Elecraft] time for KPA1500 - but why "no tubes?"

[Ron D'Eau Claire]

Well, Don, it's been a number of years since I homebrewed an amp, but from
what I recall a pi-net wouldn't meet the later FCC regs and a Pi-L network
only sufficed over a fairly narrow matching range. 

By the 1970's I was counting on my outboard "antenna tuner" that matched my
open wire feeders to provide the added spur suppression to meet FCC regs
even though I was still using a tunable Pi-L network on the output of my
homebrew rig. 

73, Ron AC7AC

-----Original Message-----

WOW,  I do not understand the distinction - there must be some harmonic 
suppression circuits that reduce the 2nd harmonic emissions from an 
amplifier (40 dBc if I recall), so whether that is done using a fixed 
tune output circuit, or whether that is achieved by the use of an 
external antenna tuner is a moot point.  The bottom line is that 
somewhere in the path between the PA tubes (transistors, MOSFETs), there 
must be a path from the grid(, base, plate) to ground that will afford a 
transition to 50 ohms (and X - j0) solution that will yield greater than 
5 watts on all bands (or in the case of the K3, 6 meters).

So use whatever tuner matching section between the amplifier and the 
antenna is a good and prudent challenge.  The inductance at the highest 
frequency will be greater than 3 times the 'oscilloscope oscilloscope 
and probe -

73,
Don W3FPR