[Elecraft] Question about K2 mod for optimizing it for 5W CW

[Alexey Kats]

No worries, I'll do that (I hate it myself when I have to work on
customized equipment when the owner either forgot about it, or didn't
even know about it since it's not the original owner). Fortunately,
the last time it happened with me was many years ago. And the most
embarrassing part was that when I figured out what was customized it
was ME who did it. (Even though it was many years ago and even in a
different country I still feel ashamed by that experience.)

On Mon, May 31, 2010 at 6:50 AM, Don Wilhelm <w3fpr at embarqmail.com> wrote:
> Alexey,
>
> The R2 that is referred to by DK3RED is on the Front Panel - it is the power
> control pot.
>
> There will be no change to any of the alignment procedures with the change
> in the T4 winding ratio.
>
> Please put a sticker inside your K2 stating that the T4 winding ratio is
> intentionally changed to optimize efficiency at 5 watts.  I have worked on
> several K2s where this change was made, then forgotten about (or the K2
> subsequently sold), and then the KSB2 and/or KPA100 was added, and the owner
> wondered why it did not operate correctly.
>
> 73,
> Don W3FPR
>
> Alexey Kats wrote:
>>
>> Sorry, I managed to press the wrong key and sent it before I finished it.
>>
>> Anyway... I know that older version of K2 manual refers to changing
>> winding of T4 transformer to 2:2 (instead of original 2:3) in order to
>> increase efficiency of CW performance on 5W or less. Is it still
>> applicable to the current version of K2? I am not interested in SSB
>> mode at all, so limiting max power to 5W is acceptable. I simply want
>> to know whether the rest of tuning instructions will be the same if I
>> change T4 winding according to those directions from rev C manual?
>> (25-30% decrease in current drain is quite important when operating
>> from batteries.) In any case, I am going to add 6.8k resistor to the
>> R2 (of course it depends on the total resistance of R2 in the current
>> kit) on control board according to DK3RED mod (which will limit max
>> power to about 5W anyway), and I want to limit current consumption as
>> well if I can.
>>
>



-- 
Alexey Kats (neko)