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

[Don Wilhelm]

  Leigh,

Elecraft is currently shipping KX1s with the 2SC2166 again.  I have 
built 4 in the last month and all 4 have that transistor.

The thermal pad provides better heat conduction and should not be 
eliminated if a plastic tab transistor is used - only the shoulder 
washer is eliminated.

73,
Don W3FPR

On 2/9/2011 7:21 PM, Leigh L. Klotz Jr WA5ZNU wrote:
> 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 and here, in this erratum superseded by the revision E manual which shows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
>