K2 Keying mod Questions

[Ken Miller K6CTW]

All,

Now that I want to add some power to the K2 so that it could become a full backup station (instead of just my QRP contesting rig) I find that I may need to do some additional things to the rig. My K2 (serial # 455) does have most of the mods in it but one that I didn't do was the keying mod.  However, when I went to order it the other day I found that mod is no longer available from Elecraft.

Is there a replacement modification that does the same thing that uses different parts?

The reason I ask about the keying mod is that it was noted that it was needed when using the K2's 100 watt amp and I was wondering if that still holds for the latest version of the K2 amp and also for the KXPA100?

Also, I don't think I need to do the mod to the keying before I upgrade the firmware.  Am I correct in that?

Thanks in advance for any ideas/suggestions/etc.

73 - Ken Miller, K6CTW


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[Don Wilhelm-4]

Ken,

The Elecraft kit for the K2 Keying Waveshape mod is no longer available
because the small PIN diode to be used at RF Board D36 is no longer
available as a leaded component - however an SMD solution is available,
read on if interested.

I do recommend that the mod be installed when the KPA100 is added to
eliminate the key-clicks that are not apparent with the QRP K2, but do
become a problem with the 100 watt amplifier.
I also recommend that the mod be added when the QRP K2 is used with any
amplifier.

Even though the mod kit is not available, there is an alternative -
order the SMT-1B board (PN E120014) from Elecraft and download the
latest K2 Owner's Manual from the Elecraft website and install it as
instructed in the manual on page 60.

That is *not* all there is to the mod.  The other required components
are a 270k resistor to be installed at R21 on the Control Board, an 82k
resistor to be installed at the D3 CB location, a change in the value of
C31 to 0.01 uF, the addition of a 10 uF capacitor from U8 pin 2 to
ground, a 0.01 uf capacitor between the upper end of R21 and the base of
Q8.  There is also a PC trace to be made between U10 pin 3 and RP2 pin 2
on the Control Board.

So if you wish to add the Keying Waveshape Mod to your K2, it is
possible, but not as a kit from Elecraft - you will have to order the
parts individually, or find the 270k and 82k 1/4 watt resistors as well
as 2 - 0.01 uF capacitors and a 10 uF electrolytic capacitor from your
junkbox.

The firmware must be updated when this mod is installed unless you
already have 2.04 installed.

You likely need the mod instructions to know where to make the PC trace
cut, and I can email them to you.  Send me a request off-list and I will
send them to you.  Just remember that the instructions for replacing RF
Board D36 must be replaced by the instructions in the new K2 manual page 60.

73,
Don W3FPR

On 10/12/2014 5:44 PM, Ken Miller K6CTW wrote:

> All,
>
> Now that I want to add some power to the K2 so that it could become a full backup station (instead of just my QRP contesting rig) I find that I may need to do some additional things to the rig. My K2 (serial # 455) does have most of the mods in it but one that I didn't do was the keying mod.  However, when I went to order it the other day I found that mod is no longer available from Elecraft.
>
> Is there a replacement modification that does the same thing that uses different parts?
>
> The reason I ask about the keying mod is that it was noted that it was needed when using the K2's 100 watt amp and I was wondering if that still holds for the latest version of the K2 amp and also for the KXPA100?
>
> Also, I don't think I need to do the mod to the keying before I upgrade the firmware.  Am I correct in that?
>
>

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