Sunday, November 11, 2012

499.5 kHz QTX

again a page full continuous decodes of WE6XGR  Sunday morning.
only 1 time decoded   partly  WE2XGR/2  in FN31LS
weak signals  -17dB  as best only

 Overall propagation weak.  In the WAERTTY  low activity


0148 -25  1.8   0.499500  0 WE6XGR FN12 50
0154 -27  2.4   0.499450  0 <...> FN31LS 47
0204 -25  1.8   0.499500  0 WE6XGR FN12 50

testing my QTX  500kHz  I have used that one before at 502.4 kHz in 2010
The first power on the 6.3A fuse was blown.
Already lost 2 IRF540 while testing the output on a dummy load
trying to tune down to 475 kHz  gave high currents and lost the IRF540
at 500 it seems  to work okay.
If  I can believe my power meter the output is well over 100W
at 6A 24V input  never had that much output from this simple but genius design.
But the IRF540 can not handle this level and breaks down after 10seconds   good that I have got some spares but it puzzles me how could I have used this in 2010 for WSPR  without failure so long
WSPR  having 2min. TX  periods.
It is clear that this is still QRP in the MW bands.  Only with exceptional propagation decodes are possible in USA. And propagation for the low bands have not been as good as a few years back.
  My QTX  is still in experimental form..
  The  digital driver part 2 legs up IC's and ceramic 500kHz resonator  are no longer used.
The K3 was  and now the FLEX1500 is direct connected to the  totem pole driver input of the QTX.

WE6GXR  and others using 1kW 100% duty cycle. in a good TX antenna.
with a fb professional designed TX.

http://www.w1vd.com/137-500KWTX.html




Driving it with the Flex1500  at XVTX/C output  in XVTR mode






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