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Showing posts from July 23, 2017

RF_AMP 45W EBAY

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Very well designed, high quality PCB all parts neatly packed. With the correct diagram relative easy to build. The newest PCB is June 2016 documentation pictures shown at Ebay are outdated  incredible  value for money 14$ Although could not yet test with RF  due too high bias Q2 0.6A - 0.7A even with shorted B-E  0.6A flowing Considering the very low prize  the supplied 2SC1971 might be a fake Mitsubishi does not longer produce this or replacements TO220 medium power RF transistors?  If someone could give a hint which eBay  2SC1971 good quality original Misubishi  is a real working one That would be much appreciated 
left is the supplied "2SC1971" not working 0.6A and not adjustable bias right is a better working possible original Misubishi it is 1mm smaller  DutchRFshop With that one i could adjust the bias to 100mA   ( diagram below  R5=330 OHm)  
 the bias of the IRF530 need to be about 25 50mA  no more no less for max gain it is a bit tricky adjusting the 2 potmeters the…