14-05-2015, 08:21 AM
(This post was last modified: 14-05-2015, 08:25 AM by Old Sparky.)
Germanium 'point contact' diodes such as the AA119, which can be used to replace failed detector and AGC diodes in many, if not most, transistor radios, are available from most suppliers such as CPC, RS, Maplin, etc., though I haven't checked availability lately. As to AF117s, personally I replace them, until recently with AF127s, though these are now somewhat expensive. There is a Russian Transistor, type GN322, available from several eBay sellers, which can also replace AF11x transistors. Both the AF127 & GN322 are in TO-72 packages with shorter leads than the AF11x types. The pin-outs differ between the AF12x series & the GN322, the latter having the same pin-outs as the AF139, so care must be exercised when fitting them. With regard to the AA119, and other diodes, they must be fitted with the correct polarity. This can easily be checked with the 'Diode test' function on a DMM, or on a low ohms range of an analogue multimeter.
