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Showing posts from December 8, 2012

How low can you go

Have been busy to improve  receiving 137kHz  2200m. I got DCF39  now 70dB s/n sometimes 75 dB  that's as strong as our MW Broadcast stations 1008 and 747kHz Replaced the preamp IC by an LH005 op-amp tested some others we have some real expensive low bias FET op-Amps at QRL  like the LH005 AD549 I could test replacing the CA3041  some difference found in gain and IMD. the OPA124p gave to much IMD possible to much gain The best performer was the LH005  having not to much gain in the used ciquit. Found the K9AY is not good enough  for this bandThe inverted-L gives best s/n trying to decode  WE2XGR at 137.700  last night had the best receiving results until now. Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az  2012-12-07 06:16   GV7FTX   0.137688   -26   0   QG75   0.1   PA0O   JO33hg   15870   329   2012-12-07 00:40   G8HUH   0.137617   -24   0   IO81mg   0.05   PA0O   JO33hg   688   67   2012-12-07 01:28   DF6NM   0.137580   -8   0   JN59nj   0.5   PA0O 


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