Am 13.09.2018 um 22:18 schrieb Kees T:
I think enough work has been done to say the 3 sets of 2N3904 transistors should be replaced with 3 sets of 2N2222A transistors. The 2N2222A is a great transistor but has been around a while and most retailers have classified them as "obsolete" and dumped the plastic versions to surplus dealers to sell. They still sell the TO-18 metal can versions at quite high prices because the military still needs them to repair "stuff". Many surplus dealers now have the plastic 2N2222A parts available for pennies on places like ebay.
Have found some 2N222A (metal) in my junkbox. They are labeled as "COIL 2N222A" Hfe around 145 but also some with Hfe around 250. If I replace the 6 2N3904 in the PA driver stage by 2N222A how the PA will be improved by this change? Must the 2N222A be paired?
Sorry, tried to find out the begin of the discussion but got stuck in the "where to buy" discussion.
73 Matthias, DD7NT
