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

[Guy Olinger K2AV]

I have K2 #1239.  I did all the A to B mods, and the rest of them, and
added the DSP.  Made a huge difference by my reckoning.  I did them all at
once.  Gl & 73, Guy.

On Thu, Feb 23, 2012 at 10:14 PM, Don Wilhelm <w3fpr at embarqmail.com> wrote:

> 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
> >
> >
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