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List:       elecraft
Subject:    Re: [Elecraft] Question about K2 mod for optimizing it for 5W CW
From:       Vic K2VCO <vic () rakefet ! com>
Date:       2010-05-31 15:31:34
Message-ID: 4C03D656.8070701 () rakefet ! com
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On 5/31/2010 6:59 AM, Alexey Kats wrote:

>>> 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.

Keep in mind that the 25% decrease in current draw applies only when the key is down. 
Assuming that you are operating in contest mode and running stations you may be 
transmitting half of the time. During the time you are transmitting the duty cycle will be 
about 50%.

So the key will be down a maximum of 25% of the time (and if you are doing 
search-and-pounce, as you must as a QRP contester, it will be significantly less). So you 
have a 25% improvement x 50% transmit time x 50% duty cycle, which translates to only a 
6.25% reduced current draw overall.

Of course if you are operating casually, listening and ragchewing, the improvement will 
even be smaller.

Is it worth permanently crippling your K2 so that it cannot produce the 10-15 watts it is 
capable of making, and which in some circumstances you might be happy to have, for this 
small improvement?

I've never understood the enthusiasm some have for this modification.
-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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