Update: it now looks like increasing the current DOES degrade the NF. The Motorola LT1001A datasheet (now linked to from my preamp page) indicates that. I couldn't find a similar datasheet for the 2N5109.
73, Mike www.w0btu.com Does anyone want to make an educated guess as to how W7IUV's emitter > resistor modification may have affected the NF? > > My guess is that the NF was changed little if any. I'm sure it helped the > signal-handling capability. > > The only transistor I've ever used in that circuit is a TRW LT1001A. It > had slightly better specs than the 2N5109. > > The original schematic is at > www.w0btu.com/W0BTU-broadband-preamps.html and the transformer I used in > the photos was W8JI's idea (in the early 1980s). > > <http://www.w0btu.com> > _________________ Topband Reflector Archives - http://www.contesting.com/_topband