Mni tnx Rik for your
answer!
No, you didn’t
spoil the fun at all ;-)
I have some remarks/ideas.
The coil losses
increase linear with the power but not more than linear. So, 10x the power
wouldn’t decrease the antenna efficiency (if no arcing occurs, of
course). If we assume an antenna, e.g. in 8m height with many toploads, then
the efficiency will be poor but the capacitance will be high and thus the
needed L will be small. Therefore we get a low voltage even with very high
power and due to the low efficiency we will keep the legal limit. So, if one
has no possibility to increase the antenna height QRO is one choice, especially
when the operator is already in pension and cannot do a qso in
qrss10000000000000000000000000 any more ;-)
It should be
possible to run a TX directly of the mains (giving about 330V DC). But for
10kW the PSU current would be 33A, requiring something like a 60000uF/450V
elco, these large HV elco's cost a fortune (at QRL we recenty had to replace a
4700uF/450V capacitor, it costed over 200 Euro).
And for a Class-D / Class-E amp running of 330V a 900V power FET might be a bit
on the edge for a foolprove TX (but since you are spending a fortune on elco's
you can spend some more money on 1.5kV devices ;-) ).
Yes, you are right. But i
mean i USA, where the voltage is 110V, you get about 155V
and thus the 900V FET would have 6 times more. For a class e mode PA, 4x the
voltage can be reached when SWR is correct(!) so there would be a goog savety
factor. About the Capacitors: You could reduce the needed C when using a 3
phase system (of the kitchen oven ;-) ). Then you would get about 268VDC and
therefore a factor 3,35 to the 900V which will be critical for the FETs when
SWR is not absolutely constant 1:1, so better using a
IXFH24N100 ;-)
Really nice, that
conversation! Tnx!
73, Stefan / DK7FC
