Hi Joe,
Class E is fascinating and can be high efficient, 98% or so. However the
output impedance has to be quite exactly 50 Ohm +-j0! A SWR of 1.5 can
reduce the efficiency significantly so that all the advantages of the
class E design are lost.
Thus, i'm using class-D designs. I have 2 PAs for 630m. A small one
running at 12 VDC,
https://dl.dropboxusercontent.com/u/19882028/MF/100W-475KHZ-PA.png and
https://dl.dropboxusercontent.com/u/19882028/MF/DK7FC%20472%20kHz%20PA%2015W%2B100W.JPG
and a large one giving 0...1.2 kW, running as a H bridge, switching
directly at 320V DC.
The efficiency can easily reach more than 90% too.
For you, i assume a normal class D using 2 (or 2x2) FETs against ground,
using a ferrite output transformer may be the best choice. This design
is used by many active MF stns, i know.
What power range do you inted to realise?
73, Stefan/DK7FC
Am 28.03.2014 00:24, schrieb [email protected]:
Hi Stefan,
I have some IRFP140BPF hexfets. Using Alan's G3NYK Class E
design spreadsheet for 200 watts at 13.8 Vdd gives 144 and 119 nf
for C1 and C2 and 1.14 uH for L. I have used silver mica for C1 and C2
but these are expensive. What do you use? I remember mentioned your
class e experiments.
73
Joe
On Wed, 26 Mar 2014, Stefan Schäfer wrote:
Am 26.03.2014 19:36, schrieb [email protected]:
Perhaps some day I will QRO!
Joe
Yes, please :-)
73, Stefan
|
