700Watts (or more) direct from Eu mains voltage
http://www.g4jnt.com/137tx.pdf
With a bit less safety margin, 1kW is quite feasible
Andy
www.g4jnt.com
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2009/12/15 Stefan Schäfer <[email protected]>:
> Mni tnx Rik for your answer!
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> No, you didn’t spoil the fun at all ;-)
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> I have some remarks/ideas.
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> 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 ;-)
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> 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 ;-) ).
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> 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 ;-)
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> Really nice, that conversation! Tnx!
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> 73, Stefan / DK7FC
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