[KX3] Digital modes: proper ALC for full output power?

[Julia Tuttle]

Hi,

I'm trying to get my KX3 set up for FT8 and JS8call and all those fun
modes, and I'm running into a bit of trouble with setting the audio
interface volume and mic gain.

The KX3 manual suggests aiming for no more than 3-4 bars of ALC indication
to prevent distortion, but if I do this, I don't always get full output
power.

Initially I chalked this up to the firmware reducing output power from
heat, but it's proportional: if I ask for 10 W, I get 7; if I ask for 5, I
get 3, and so on.

It also doesn't always happen!

Any ideas?

73s,

Julie
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[Bill Frantz]

Hi Julia -

Running the Transmit Gain procedure (page 33 in my manual) is
the usual first thing to do when the power output seems "wanky".

The general recommendation for drive level from the computer is
4 bars with the 5th flashing. If the drive level is too low, the
output power will start off low and then build to the power
output setting on the radio. If the drive level is 4 bars with
the 5th flashing, the radio will start close to the power output setting.

If the drive level is too high, you will drive the radio into
using automatic level control which will produce a distorted
signal on the air.

If the output power is stablising at levels lower than the
setting, try the Transmit Gain calibration procedure.

73 Bill AE6JV

On 3/4/21 at 2:35 PM, [hidden email] (Julia Tuttle) wrote:

>I'm trying to get my KX3 set up for FT8 and JS8call and all those fun
>modes, and I'm running into a bit of trouble with setting the audio
>interface volume and mic gain.
>
>The KX3 manual suggests aiming for no more than 3-4 bars of ALC indication
>to prevent distortion, but if I do this, I don't always get full output
>power.
>
>Initially I chalked this up to the firmware reducing output power from
>heat, but it's proportional: if I ask for 10 W, I get 7; if I ask for 5, I
>get 3, and so on.
>
>It also doesn't always happen!
>
>Any ideas?
>
>73s,
>
>Julie

-------------------------------------------------------------------------
Bill Frantz        | Airline peanut bag: "Produced  | Periwinkle
[phone]      | in a facility that processes   | 150
Rivermead Rd #235
www.pwpconsult.com | peanuts and other nuts." - Duh |
Peterborough, NH 03458

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[Julia Tuttle]

Ah, okay, the manual didn't tell the whole story. I assumed if I got 0-1
bars, I was loud enough to hit full output power. I tried aiming for 4-5
bars and I'm getting full output power. Thanks to the folks who suggested
that!

So while I'm here, is it okay to run 15 W out for 15 seconds straight at a
50% duty cycle? The manual recommends 5 W, but FT8's duty cycle seems to
keep my PA temperature under 45 C. Are there other issues besides
temperature I need to worry about?

On Thu, Mar 4, 2021 at 9:36 PM Bill Frantz <[hidden email]> wrote:

> Hi Julia -
>
> Running the Transmit Gain procedure (page 33 in my manual) is
> the usual first thing to do when the power output seems "wanky".
>
> The general recommendation for drive level from the computer is
> 4 bars with the 5th flashing. If the drive level is too low, the
> output power will start off low and then build to the power
> output setting on the radio. If the drive level is 4 bars with
> the 5th flashing, the radio will start close to the power output setting.
>
> If the drive level is too high, you will drive the radio into
> using automatic level control which will produce a distorted
> signal on the air.
>
> If the output power is stablising at levels lower than the
> setting, try the Transmit Gain calibration procedure.
>
> 73 Bill AE6JV
>
> On 3/4/21 at 2:35 PM, [hidden email] (Julia Tuttle) wrote:
>
> >I'm trying to get my KX3 set up for FT8 and JS8call and all those fun
> >modes, and I'm running into a bit of trouble with setting the audio
> >interface volume and mic gain.
> >
> >The KX3 manual suggests aiming for no more than 3-4 bars of ALC indication
> >to prevent distortion, but if I do this, I don't always get full output
> >power.
> >
> >Initially I chalked this up to the firmware reducing output power from
> >heat, but it's proportional: if I ask for 10 W, I get 7; if I ask for 5, I
> >get 3, and so on.
> >
> >It also doesn't always happen!
> >
> >Any ideas?
> >
> >73s,
> >
> >Julie
> -------------------------------------------------------------------------
> Bill Frantz        | Airline peanut bag: "Produced  | Periwinkle
> [phone]      | in a facility that processes   | 150
> Rivermead Rd #235
> www.pwpconsult.com | peanuts and other nuts." - Duh |
> Peterborough, NH 03458
>
>

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