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Saturday, August 13, 2016

KB8M's Mighty Mite -- Beware the Treacherous P2N2222!

Doug KB8M did a beautiful job with his Michigan Mighty Mite.  But, as often happens, it still didn't work. He turned to us for advice.  I gave him a long list of things to check, but Pete brought the power of superior tribal knowledge to the problem and spotted the defect immediately: The transistor was in backwards.  It is a P2N2222.  That means the pin out it C-B-E  not the usual E-B-C.  I had fallen into this trap with one of my BITX rigs and had to pull out and reverse many of those transistors.  Fortunately for Doug he had used a socket for the transistor.  TRGHS!!!!!!!!!!!!!  JOO!!!!!!!!!!!


4 comments:

  1. Look for one of the cheap Chinese eBay testers GM328A they are only a few dollars and they do LCR and give pinouts for diodes and transistors FETs the lot! Got a junk box full of old transistors, just test them quickly Bill. Cannot be without mine.
    73 David GM4JJJ

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  2. The Mighty Mite needs a mate!

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  3. I will also say it has "soul". My 8-yr old son Wyatt helped me wind the coil. He was excited to see/hear the MMM transmit on our receiver. I used a socket for the transistor and crystal. When I made the PCB I even etched "CBE" at the transistor socket so I wouldn't do that! Fun times

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