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KX3 - Power out vs. ALC bars

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John Huggins, kx4o

KX3 - Power out vs. ALC bars

Hello all,

I had a successful binge of RTTY this weekend in the NAQP using the KX3,
audio interface and N1MM (MMTTY).

This was hastily assembled after the audio interface arrived Saturday.
Things came together splendidly whereupon I made QSOs with west coast
stations from Virginia. Only after the contest did I realize I was a
bit too conservative with the output power. I set the interface's audio
transmit pot to yield not 4, not 3, not 2, not 1, but ZERO ALC bars. I
did confirm transmit using a separate receiver and, of course, the
contacts I made were quick, simple and productive. I saw it worked so
just forgot about the ALC settings.

I read in the manual the suggestion to adjust audio-in to yield about 4
bars ALC. My radio power was set to 5 watts.

Question:
Is there a chart of graph I've somehow missed relating ALC bars to the
percentage of power output setting?

Thanks.
John, kx4o
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Barry K3NDM

Re: KX3 - Power out vs. ALC bars

John,
The manual states that you should keep the ALC bars in the not to exceed 5 range. This keeps distortion down. Power is controlled by other means. As the radio is not rated for 100% duty cycle for 10 Watts, I would recommend that you stay under 4 Watts for the digital modes if running barefoot.

73,
Barry
K3NDM

----- Original Message -----

From: "John" <[hidden email]>
To: "elecraft" <[hidden email]>
Sent: Monday, March 2, 2015 12:13:05 AM
Subject: [Elecraft] KX3 - Power out vs. ALC bars

Hello all,

I had a successful binge of RTTY this weekend in the NAQP using the KX3,
audio interface and N1MM (MMTTY).

This was hastily assembled after the audio interface arrived Saturday.
Things came together splendidly whereupon I made QSOs with west coast
stations from Virginia. Only after the contest did I realize I was a
bit too conservative with the output power. I set the interface's audio
transmit pot to yield not 4, not 3, not 2, not 1, but ZERO ALC bars. I
did confirm transmit using a separate receiver and, of course, the
contacts I made were quick, simple and productive. I saw it worked so
just forgot about the ALC settings.

I read in the manual the suggestion to adjust audio-in to yield about 4
bars ALC. My radio power was set to 5 watts.

Question:
Is there a chart of graph I've somehow missed relating ALC bars to the
percentage of power output setting?

Thanks.
John, kx4o
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John Huggins, kx4o

Re: KX3 - Power out vs. ALC bars

Is it safe to say my very low input audio level was compensated by the
KX3's power control loop to yield 5 watts out (the actual radio power
setting)?

It's hard to shake my Icom digital interface habits.

Thanks.
John, kx4o

On 3/2/2015 12:34 AM, [hidden email] wrote:

> John,
> The manual states that you should keep the ALC bars in the not to
> exceed 5 range. This keeps distortion down. Power is controlled by
> other means. As the radio is not rated for 100% duty cycle for 10
> Watts, I would recommend that you stay under 4 Watts for the digital
> modes if running barefoot.
>
> 73,
> Barry
> K3NDM
>
>

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Barry K3NDM

Re: KX3 - Power out vs. ALC bars

Actually, the Icom followed the same rules, but you got there differently. I suspect that your Icom is rated at 100 Watts peak. Meaning you need to adjust the input to keep the level down to 1/4-1/3 the rated output. And, you may have need to back down on the input auto further so as to not generate too much ALC action. This satisfied two problems, distortion and over heating of the finals. The rules are the same for the KX3, keep distortion low and don't over heat the final. Elecraft says not to kick up too many bars for ALC. That's for distortion. Use the power control to keep your power down to the 100% duty cycle level. Your audio input controls the ALC. I don't have my manual handy, but I can say it is covered there.

73,
Barry
K3NDM

----- Original Message -----

From: "John" <[hidden email]>
To: [hidden email]
Cc: "elecraft" <[hidden email]>
Sent: Monday, March 2, 2015 12:44:07 AM
Subject: Re: [Elecraft] KX3 - Power out vs. ALC bars

Is it safe to say my very low input audio level was compensated by the KX3's power control loop to yield 5 watts out (the actual radio power setting)?

It's hard to shake my Icom digital interface habits.

Thanks.
John, kx4o

On 3/2/2015 12:34 AM, [hidden email] wrote:

John,
The manual states that you should keep the ALC bars in the not to exceed 5 range. This keeps distortion down. Power is controlled by other means. As the radio is not rated for 100% duty cycle for 10 Watts, I would recommend that you stay under 4 Watts for the digital modes if running barefoot.

73,
Barry
K3NDM

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Don Wilhelm-4

Re: KX3 - Power out vs. ALC bars

In reply to this post by John Huggins, kx4o

John,

The KX3 (or the K3 or K2) will not control its power output properly
unless you drive the audio sufficiently.
The "ALC meter" on the K3 and KX3 is a combination of an audio level
meter and ALC meter. Below 5 bars indicated is really the 'no ALC'
range. So adjust the soundcard audio and/or the KX3 mic gain to produce
4 bars on the ALC meter.
After doing that, adjust to the desired power with the power knob.

Remember that the KX3 will attempt to maintain the power level
requested, so if your audio level is too low, the power control will
become erratic and creep up and down. What I am saying is that
attempting to control the power output with the audio level will not
result in proper operation.

73,
Don W3FPR

On 3/2/2015 12:44 AM, John wrote:

> Is it safe to say my very low input audio level was compensated by the
> KX3's power control loop to yield 5 watts out (the actual radio power
> setting)?
>
> It's hard to shake my Icom digital interface habits.
>
> Thanks.
> John, kx4o
>
> On 3/2/2015 12:34 AM, [hidden email] wrote:
>> John,
>> The manual states that you should keep the ALC bars in the not
>> to exceed 5 range. This keeps distortion down. Power is controlled by
>> other means. As the radio is not rated for 100% duty cycle for 10
>> Watts, I would recommend that you stay under 4 Watts for the digital
>> modes if running barefoot.
>>
>> 73,
>> Barry
>> K3NDM
>>
>>
>
> ______________________________________________________________
> 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]
>

John Huggins, kx4o

Re: KX3 - Power out vs. ALC bars

In reply to this post by John Huggins, kx4o

Thanks Walter. I think I understand now.

What is the loop bandwidth of the power control loop?

Thanks.
John, kx4o

On Mon, March 2, 2015 05:54, Walter Underwood wrote:

> No. Most likely the power varied as it was hunting for the right level.
> It probably started low then increased power slowly throughout each
> transmission.
>
> wunder Walter Underwood
> [hidden email] http://observer.wunderwood.org/ (my blog)
>
> On Mar 1, 2015, at 9:44 PM, John <[hidden email]> wrote:
>
>> Is it safe to say my very low input audio level was compensated by the
>> KX3's power control loop to yield 5 watts out (the actual radio power
>> setting)?