[Lowfer] Lowfer Final Transistors.

[LEE BAHR]

Johan,

OK on the matching issue.

How do you pick a transistor when looking at the specs?  hfe for speed?  How 
do you know if you are picking one that switches fast, hard with low 
saturation?  I'm looking at a Motorola spec sheet on a zillion small 
transistors and would love to use an educated guess and buy some for tests 
which might work great and are easily obtainable today and are not a 
discontinued transistor.  I don't have a clue other then to try and pick 
some close to the specs for the ones members are now using.  What confuses 
me is members are saying a MPS6602A with a min hfe of 50 works better then a 
PN2222A with a min hfe of 100.  I would think an hfe of 100 would switch 
faster then one with a hfe of 50.  I have no idea how you tell if one 
switches hard with low saturation.  Is this subject too deep and over my 
head to understand?

Thanks for your help, Johan.

Lee, w0vt
Confused and sleepless in Houston, Tx, USA


> Lee,
>
> transistor matching is not an issue in a class D switching PA. You just 
> want
> them to switch fast and hard with low saturation voltage. Just like 
> relays, only
> faster :-)
>
> 73
> Johan SM6LKM
>
>