On Jun 13, 6:54*am, steveeh131047 wrote:
On Jun 13, 12:05*am, Jim Lux wrote:



Ham applications in any case are kind of an odd thing, efficiency-wise,
since the limit is on RF power at the transmitter output connector.

Jim,

That's not the case in the UK. The licence conditions specify "....
power supplied to the antenna by a transmitter ...."

Steve G3TXQ

How interesting, so in both VK and UK (mixing abbreviations).. the
"reference plane" for the measurement is potentially "after" the
transmission line. The 5kW Active Antenna Tuner lives!

Here in the US, I'm sure the rule is interpreted the way it is because
of the heritage of "1kW DC power to the final stage" rule, which in
turn came from pre-ham radio rules for marine transmitters using
sparkgaps, etc... It was simple change from measuring plate current/
voltage to hooking a power meter at the output connector. I wonder if
anyone ever measured RF power on a non-50 ohm transmitter in an
enforcement action?

My father and grandfather both had stories, apocryphal perhaps, about
clever hams having very large "exciters" that fed through a relatively
low power "final stage"... using the final tube as a coupling
capacitor, perhaps, with unity gain.