HI Curt.. It almost sounds like there is a different lead arrangement on the 3393. Any well designed circuit of that era would have had to tolerate the typical high variability of Hfe to avoid tedious hand picking of parts, although that may have been done in this case.
Tom Holmes, N8ZM Tipp City, OH EM79 > -----Original Message----- > From: drakelist-boun...@zerobeat.net [mailto:drakelist-boun...@zerobeat.net] > On Behalf Of Curt Nixon > Sent: Tuesday, February 26, 2013 10:40 AM > To: Drake Forum > Subject: [Drakelist] R4A-B Detector Amp Q5 > > GM All: > > Has anyone else had trouble getting a general purpose sub working in the Q5 AM > detector amp position? > > I tried several close NTE GP subs and also a 3393 which is same parameters ex > Hfe which is slightly different. > > The transistor comes on but with the grounded emitter, pulls the collector voltage > to near zero. As soon as I put in a "real" orignal > 3394 from a R4A, it works as it should--good fidelity and collector voltage at about > 5V from the supply rail of 10V. > > Is this design so sensitive to Hfe as to be marginal or need to be hand selected? > Certainly the 3393 is well within the spec range of the 3394. > > Thanks > > Curt > KU8L > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
