Re: [KX1] Variation in driver transistors (e.g. 2SC2166)

Posted by Leigh L. Klotz Jr WA5ZNU on Feb 10, 2011; 12:21am
URL: http://elecraft.85.s1.nabble.com/KX1-Variation-in-driver-transistors-e-g-2SC2166-tp6010045p6010111.html

Here's some info to read:
  http://elecraft.365791.n2.nabble.com/KX1-Q6-question-td662532.html
and here, in this erratum superseded by the revision E manual which shows the changeover:
  http://www.elecraft.com/manual/KX1_Owners_Manual_Errata_Rev_D-1.pdf

It seems that Elecraft went from a 2SC2166 to a 2SC5739 for RoHS compliance.

A side benefit is that the new part eliminates a thermal pad, shoulder washer, and thus a potential for a short from the KX1 build.

Some have reported improved output on 20M with this part, albeit with the usual warnings about too much power causing you trouble later if you don't have a great match to your antenna, a strong possibility under the KX1 normal operating conditions.

Leigh/WA5ZNU