[Elecraft] K2 audio issue on CW T/R transition

[Don Wilhelm]

Eric,

I really cannot associate any change in sidetone pitch ("chirp") with 
the change of RF and AF gain pots, but I would strongly recommend that 
you add the sidetone pitch (10k series resistor and 82 mHy shielded 
inductor) changes to your Rev A K2 to give a better sidetone pitch.  In 
fact, I would recommend all the K2 A to B mods including a crystal 
change if your K2 SN is less than 2560.

The Alternate AF Gain Wiring Mod will not alter the "chirp" behavior, 
but it will preserve your AF Gain control for the future.  The mod 
removes the DC current flow through the AF Gain control and will prolong 
its life.

Actually, I would recommend that you install all the A to B mods 
(including the optional ones) on your K2.  While not mandatory, you will 
notice a difference in your K2 performance - it is well worth the effort 
- include the Thermistor upgrade and the K2 Keying Waveshape Mod to make 
things complete.

73,
Don W3FPR

On 2/23/2012 9:35 PM, William Eric McFadden wrote:
> My K2 has recently begun making a slight bit of a "chirp"-noise in my
> headphones on the T/R transition when I do CW. Not a chirp in the classic
> CW sense of the word, when the other guy hears it, but a little bit of a
> tone in my own headphones.
>
> My K2 is a 10-watt "rev A" unit, firmware revision 2.04P 1.09 with KSB2,
> K160RX, KAT2, and KNB2 options. The only thing I've done to the rig
> recently is to replace the AF and RF gain pots and I didn't notice this
> "chirp" phenomenon until sometime after I replaced the pots. This K2 does
> not have the alternate AF mod installed.
>
> I've noticed this phenomemon in 80m CW, and I key with a manual key. I've
> heard it with crystal filter settings of 700 and 400Hz. It doesn't seem to
> matter if I have AGC set to fast or slow. I do tend to have the RIT
> engaged--my QSO-buddy's old OMNI D has a bit of drift.
>
> Any suggestions? Did I break something when I replaced the pots?
>
> Tnx es 73,
> http://home.frognet.net/~mcfadden/wd8rif/radio.htm
>
> Eric, WD8RIF
>
>