[Elecraft] K2 keying mod details and circuit theory

[Vic Rosenthal]

W B Reese wrote:

> I would like to ask what is the rated top speed for CW with the new mod?

Looking at the pictures in the manual on the website, it appears that 
the new rise time is about 5 ms.  I measured the rise time on my K2 
without the mod as 2-3 ms.

If a dit is one element, the word PARIS has exactly 50 elements.  As you 
know, this is used as a standard word for calculating wpm.  70 wpm * 50 
elements = 3500 elements/min or 58.3 elements/sec.  1/58.3 = 17 
ms/element.  So a 70 wpm dit is 17 ms.

If it is correct as you say that a rise time more than 1/4 the dit 
length damages readability, then the 'top' speed for perect readability 
with the mod comes out to about 60 wpm (20 ms dit).

Having said that, if you don't do the mod, then you widen the bandwidth 
by a factor of about 10.  So I suggest that you obtain Wayne's app note 
when it becomes available and tune your K2 for a rise time of 4 ms 
instead of 5, giving you a safety factor of 0.25 ms.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco