On Thursday 29 September 2005 14:07, Karel Kulhavy wrote: >> >>thermal noise due to base resistance were your limiting factor. >> > >> >Because only RF transistor has transition frequency of 25GHz. >> >> Fight, but you said you were going to use this where a 2N3904 would >> have enough speed so why do you need a 25 GHz Ft? Also you said you >> were going to run at a current level low enough to drop the Ft down to >> 300 MHz. > >Because 2N3904 will have enough speed at 5mA collector current which >generates huge shot noise. 25GHz Ft will have 300MHz speed at I don't >know 1uA of current which will generate substantially less noise? > >CL<
An old C.E.T. speaking here, with 55 years experience. 2N3904's appear to be the leftovers from a lot of processes. I would not implicitly trust any one spec to be within +-100% of the spec sheet. I've not found them to be very long lived in lots of the stuff where the bean counters told engineering that 'its good enough'. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) 99.35% setiathome rank, not too shabby for a WV hillbilly Yahoo.com and AOL/TW attorneys please note, additions to the above message by Gene Heskett are: Copyright 2005 by Maurice Eugene Heskett, all rights reserved.
