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K2 audio issue on CW T/R transition

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wd8rif

K2 audio issue on CW T/R transition

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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Don Wilhelm-4

Re: K2 audio issue on CW T/R transition

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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Guy, K2AV

Re: K2 audio issue on CW T/R transition

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 <[hidden email]> 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
> >
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

wd8rif

Re: K2 audio issue on CW T/R transition

In reply to this post by wd8rif

Thank you very much for the replies.

The "chirp" I'm hearing on T/R transition isn't a shift in my sidetone; it sounds more like a geniune signal somewhere else on the band and my K2 is taking just a tiny moment to stabilize the receive frequency as the K2 switches from transmit to receive. It's a very quick little noise. I don't hear it between CW elements but do between word spaces and sometimes between characters. (I run about 20wpm with my bug.) I haven't yet checked to see if turning off my RIT changes anything.

I will probably install the Alternate AF Gain Wiring Mod at some point--I didn't want to change too many things at one time when I replaced the two pots. I will also probably perform the A to B mod at some point, too.

Eric, WD8RIF
http://home.frognet.net/~mcfadden/wd8rif/radio.htm

Mike Harris

Re: K2 audio issue on CW T/R transition

All bands? There was an advisory a few years ago about VCO voltage
limits and frequency settling time when changing state TX>RX or the reverse.

Just a thought.

Regards,

Mike VP8NO

On 24/02/2012 10:05, wd8rif wrote:

> Thank you very much for the replies.
>
> The "chirp" I'm hearing on T/R transition isn't a shift in my sidetone; it
> sounds more like a geniune signal somewhere else on the band and my K2 is
> taking just a tiny moment to stabilize the receive frequency as the K2
> switches from transmit to receive. It's a very quick little noise. I don't
> hear it between CW elements but do between word spaces and sometimes between
> characters. (I run about 20wpm with my bug.) I haven't yet checked to see if
> turning off my RIT changes anything.
>
> I will probably install the Alternate AF Gain Wiring Mod at some point--I
> didn't want to change too many things at one time when I replaced the two
> pots. I will also probably perform the A to B mod at some point, too.
>
> Eric, WD8RIF
> http://home.frognet.net/~mcfadden/wd8rif/radio.htm

wd8rif

Re: K2 audio issue on CW T/R transition

I've only noticed it on 80m.

Thanks for letting me know about the advisory--I'll look for it.

Eric, WD8RIF
http://home.frognet.net/~mcfadden/wd8rif/radio.htm

Mike Harris wrote

All bands? There was an advisory a few years ago about VCO voltage
limits and frequency settling time when changing state TX>RX or the reverse.