[AMRadio] Receive Preamp question


Peter Markavage manualman at juno.com
Sun Nov 4 14:01:12 EST 2007


Another great device choice for a front-end MOSFET is the Sony 3SK-48.
It's a drop-in replacement. Great gain and low noise make them an
excellent choice for use above 20 MHz. Unfortunately, they are not easy
to come by today in single lot quantities.

Pete, wa2cwa

On Sun, 04 Nov 2007 13:08:26 -0500 rbethman <rbethman at comcast.net>
writes:
> John,
> 
> The receiver board has MOSFETs on it.
> 
> Get out the manual and track down the "receive" MOSFET.
> 
> This same thing was fiddled with in Kenwood Transceivers.
> 
> They were initially built with 3SK45s.
> 
> We specifically replaced the 3SK45's with the 3N201s.
> 
> These four beasties, 40673s, NTE222s, 3SK45s, and 3N201s are all 
> very 
> close relatives.
> 
> We managed to get the 3N201s from someone working in the Bell Labs 
> in 
> Florida around 1980.
> 
> The 3N201 AND the 3N211 performed the best!  Dropped the noise floor 
> a 
> GOOD bit.  That makes the old FT-101 series, (And many others of 
> that 
> genre.), a good bit better than originally designed.
> 
> They are all also direct plugins for each other.  Sometimes the ONLY 
> way 
> to determine which one to use is simply try one of each in YOUR 
> application.  The minor circuit differences between the radios can 
> make 
> all the difference.
> 
> 
> Bob - N0DGN


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