[Elecraft] K3 Enhancements and Application Notes Page (CW rise time)

[Bill W4ZV]

GW0ETF wrote:
> 
> According to the Application Notes Page my K3 #145 should have an ~8ms
> rise time. However, viewed on my analogue 'scope the rise time (0 - 100%)
> is definitely shorter and nearer to 5ms with a similar fall time though
> with a sharper falling transition edge.
> 
> The notes suggest the mod is necessary to enable a future menu selectable
> envelope adjustment but I don't want to reduce my rise time to a nominal
> 5ms if it already is around that figure anyway - presumably I will end up
> with an even steeper leading edge.
> 
> Anyone else looked at keying waveforms in pre s/n 211 K3s...?
> 

The production start date for this mod could be in error on the webpage.  I
know this issue has been known about well before S/N 211.  My S/N is early
100's and it definitely needed the mod.  

Open your K3 (bottom panel closest to the front panel) and measure C222.  If
it's 0.1 uF, the mod has already been installed.  Unfortunately the only way
to tell, since SMD caps are unmarked, may be to use a capacitance meter
(unless Elecraft can suggest a better method).  I believe a meter will read
the value correctly even with the cap in-circuit.

73,  Bill

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