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KX2 Starts Off with Low Output on 10M

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Nate Jedinak

KX2 Starts Off with Low Output on 10M

Hello! I recently purchased a KX2 (#757) from a friendly member of this list.

I have a local 10m meetup I attend frequently, and I noticed a strange behavior that I'm now able to replicate. When I first switch to 10m, I have extremely low output power (one bar on the RF meter), even when set to 10w. I have to keep transmitting for 30-60 seconds, and if I do, the output power starts to work its way up to the full 10w. As you talk, you'll see 2 bars, 3, then 5, etc eventually to the full 10w. If I switch back to another band and back immediately, it will display the same behavior (start on one bar and then climb slowly), but if I stay on 10m it will continue at full output for the QSO. I isolated this problem this morning and can now replicate at will. It's not just a display issue, my local meetup actually noticed it in audio (I start off in the noise, and come out to normal over time).

I mailed Elecraft, and they suggested it was a hardware failure in the final stage. Before I return the radio for service, has anyone experienced this issue previously and found it to be a configuration issue that didn’t need hardware repair?

Thank you in advance! Other than this issue, I absolutely love the KX2. It took me 3 small HF rigs to land on it, but it suits my needs perfectly.

—Nate KE8QID

Sent from my iPhone
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Elecraft mailing list

Re: KX2 Starts Off with Low Output on 10M

I have that problem to.

My solution is to wind the power back from 10w to anything less and then back to 10w.

Paul
W6PNG/M0SNA
www.nomadic.blog

> On Feb 28, 2021, at 5:52 AM, Nate Jedinak <[hidden email]> wrote:
>
> Hello! I recently purchased a KX2 (#757) from a friendly member of this list.
>
> I have a local 10m meetup I attend frequently, and I noticed a strange behavior that I'm now able to replicate. When I first switch to 10m, I have extremely low output power (one bar on the RF meter), even when set to 10w. I have to keep transmitting for 30-60 seconds, and if I do, the output power starts to work its way up to the full 10w. As you talk, you'll see 2 bars, 3, then 5, etc eventually to the full 10w. If I switch back to another band and back immediately, it will display the same behavior (start on one bar and then climb slowly), but if I stay on 10m it will continue at full output for the QSO. I isolated this problem this morning and can now replicate at will. It's not just a display issue, my local meetup actually noticed it in audio (I start off in the noise, and come out to normal over time).
>
> I mailed Elecraft, and they suggested it was a hardware failure in the final stage. Before I return the radio for service, has anyone experienced this issue previously and found it to be a configuration issue that didn’t need hardware repair?
>
> Thank you in advance! Other than this issue, I absolutely love the KX2. It took me 3 small HF rigs to land on it, but it suits my needs perfectly.
>
> —Nate KE8QID
>
> Sent from my iPhone
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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Brian Hunt

Re: KX2 Starts Off with Low Output on 10M

In reply to this post by Nate Jedinak

The KX2 uses a control loop to set power. Make sure you have sufficient audio drive to energize the loop. Using the ALC display set the MIC GAIN so you have 5-7 bars on voice peaks, per the manual.

What MIC are you using? Have you tried the internal MIC?

GL & 73,
Brian, K0DTJ
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Nate Jedinak

Re: KX2 Starts Off with Low Output on 10M

I have replicated this behavior both with the internal as well as the MH3 external mic. Of course set at different mic gain levels, always per the manual which as you said suggests 5 bars of ALC. I have tried lower and higher mic gain settings just for fun, with the same results.

I don’t think this is an mic gain issue, as it does happen on any other band I’ve used (80, 40, 20) and only on 10m. I made a video showing the behavior here, let me know what you think: https://youtu.be/7wWd6vRYSxo

I have had great QSOs on 40 and 20 so far, and feedback that my audio is extremely low on 10 until it “warms up” and then reports there are excellent, also. I usually talk on 10m for 45-60 minutes every weekend morning and it performs well once it’s up to power.

Nate KE8QID

Sent from my iPhone

> On Feb 28, 2021, at 11:01 AM, Brian Hunt <[hidden email]> wrote:
>
> The KX2 uses a control loop to set power. Make sure you have sufficient audio drive to energize the loop. Using the ALC display set the MIC GAIN so you have 5-7 bars on voice peaks, per the manual.
>
> What MIC are you using? Have you tried the internal MIC?
>
> GL & 73,
> Brian, K0DTJ
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

Brian Hunt

Re: KX2 Starts Off with Low Output on 10M

Nate,
A couple more questions:

Does the KX2 do the same thing on CW?

Did Elecraft say anything about doing a TX gain calibration? This can be done with the KX2 utility although I haven’t done it on mine, just on my K3. It sets the per-band gain coefficients Be sure to save the current CONFIG file so you can restore it if needed. You will need a good dummy load an a stable power source. The procedure is on p. 38 of the Rev A5 Manual.

Good luck,
73,
Brian, K0DTJ
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Tim Tucker

Re: KX2 Starts Off with Low Output on 10M

Mine does that too. What works for me is to tweak the mic gain up and then
back to the same level and it starts working normally. Seems to me like
there is a firmware bug with the radio that hasn't been figured out and
addressed yet.

Tim

On Sun, Feb 28, 2021 at 6:08 PM Brian Hunt <[hidden email]> wrote:

> Nate,
> A couple more questions:
>
> Does the KX2 do the same thing on CW?
>
> Did Elecraft say anything about doing a TX gain calibration? This can be
> done with the KX2 utility although I haven’t done it on mine, just on my
> K3. It sets the per-band gain coefficients Be sure to save the current
> CONFIG file so you can restore it if needed. You will need a good dummy
> load an a stable power source. The procedure is on p. 38 of the Rev A5
> Manual.
>
> Good luck,
> 73,
> Brian, K0DTJ
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

--
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AE6LX, Amateur Radio
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