Monday, April 11, 2011


Promised a week ago, here at last, a fine example of breadboard construction:The tube in the center is the T21, a 6L6 offspring. A plain 6L6G should work fine.


  1. Very pretty, all those right angles and bus-bar looking wires. But what happens if the unit is thumped? Gonna be interesting when things vibrate.

  2. I think you'd be surprised -- it's crystal-controlled (round widget, back row, center) and the crystal-to-grid lead is pretty short.

    The usual fix for a microphonic transmitter -- and some of the "power VFO" ones were bad that way -- was to put it on another table, on typewriter pad if need be. Or even hang it on the wall!

  3. I recognize that one! It's from the 1940-ish edition of the Radio Amateur Newcomers Handbook (from the publishers of "Radio" - Frank Jones & friends). I'd now the exact date but my copy has the covers and first few pages missing. It was my grandfather's.