HF parts (was: Re: [sdiy] Anyone need any transistors? I got lots and lots...)

[Roy J. Tellason]

On Friday 13 January 2006 05:42 pm, Johannes Öberg wrote:
> Since I'm already on a bringing-up-old-threads spree...
>
> What was the conclusion here? If I find some HF transistors cheaply, can I
> use these as general purpose transistors (assuming voltage and current
> rating fits of course)? Or is the higher bandwith a problem, perhaps with
> selfoscillations or poor low end or something?
>
> /J

It seems to be the normal progression of things for more recent part numbers 
to have somewhat higher bandwidth (transition frequency or whatever that 
particular datasheet is calling it) than earlier parts,  and if that's the 
sort of part you're talking about I wouldn't expect any problems.  If,  OTOH,  
you're talking about stuff that's made for extremely wide bandwidth,  VHF,  
UHF,  and beyond,  I wouldn't expect them to work nearly as well.  The wide 
bandwidth typically also means that other parameters are going to be 
different,  the one I've noticed the most being significantly lower breakdown 
voltages.  Also wider spreads of beta.

> On 12/25/05, Aaron Lanterman <lanterma at ece.gatech.edu> wrote:
> > Quick question: If something's tagged as "RF" "UHF" "VHF" etc... is there
> > any reason I couldn't use it for audio (although it might be overkill?)

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