K3/10 Power Meter Anomaly in data mode

[Julian, G4ILO]

I haven't done any data modes operating recently so I have only just noticed an apparent anomaly in the K3 power output display that presumably has occurred since the last firmware update. The meter reading on the K3/10 shows nearly full scale when 5W is selected on the power control. An external power meter shows the correct power is being radiated, so it is definitely an issue with the meter display, which does show the correct reading on key down in CW mode, or when tuning.

Has anyone else noticed this? Only my magnetic loop control unit has a power meter that is permanently in circuit when operating so for other antennas I do rely on the K3 power meter to confirm that I am running the correct amount of power output.

[Ken Wagner K3IU]

G4ILO wrote:

> I haven't done any data modes operating recently so I have only just noticed
> an apparent anomaly in the K3 power output display that presumably has
> occurred since the last firmware update. The meter reading on the K3/10
> shows nearly full scale when 5W is selected on the power control. An
> external power meter shows the correct power is being radiated, so it is
> definitely an issue with the meter display, which does show the correct
> reading on key down in CW mode, or when tuning.
>
> Has anyone else noticed this? Only my magnetic loop control unit has a power
> meter that is permanently in circuit when operating so for other antennas I
> do rely on the K3 power meter to confirm that I am running the correct
> amount of power output.
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392
> G4ILO's Shack: www.g4ilo.com
> Zerobeat Ham Forums: www.zerobeat.net/smf
>  

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[Ken Wagner K3IU]

G'morning Julian:

I tried using MixW and PSK31 (DATA A mode on K3) just now and at first
saw somewhat you describe, however, when I reduced the Line In gain (MIC
control on front panel) I easily controlled the power out.With 5 watts
commanded on the K3 power control, Tune mode in MixW and a line gain of
about 18, 5 watts displays on the K3 and the external power meter. Now
when I click on the CQ button in MixW (F2), the K3 display still shows
about 5 watts and the external power meter shows a fluctuating power out
of 2.5 - 5 watts as the PSK signal is sent. I don't see a problem with
the power out display at all on my K3.

73,
Ken K3IU
K3 #202
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

G4ILO wrote:

> I haven't done any data modes operating recently so I have only just noticed
> an apparent anomaly in the K3 power output display that presumably has
> occurred since the last firmware update. The meter reading on the K3/10
> shows nearly full scale when 5W is selected on the power control. An
> external power meter shows the correct power is being radiated, so it is
> definitely an issue with the meter display, which does show the correct
> reading on key down in CW mode, or when tuning.
>
> Has anyone else noticed this? Only my magnetic loop control unit has a power
> meter that is permanently in circuit when operating so for other antennas I
> do rely on the K3 power meter to confirm that I am running the correct
> amount of power output.
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392
> G4ILO's Shack: www.g4ilo.com
> Zerobeat Ham Forums: www.zerobeat.net/smf
>  

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Post to: [hidden email]
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Subscriber Info (Addr. Change, sub, unsub etc.):
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[Julian, G4ILO]

Ken K3IU wrote

I tried using MixW and PSK31 (DATA A mode on K3) just now and at first
saw somewhat you describe, however, when I reduced the Line In gain (MIC
control on front panel) I easily controlled the power out.With 5 watts
commanded on the K3 power control, Tune mode in MixW and a line gain of
about 18, 5 watts displays on the K3 and the external power meter. Now
when I click on the CQ button in MixW (F2), the K3 display still shows
about 5 watts and the external power meter shows a fluctuating power out
of 2.5 - 5 watts as the PSK signal is sent. I don't see a problem with
the power out display at all on my K3.

You are correct that the K3 power meter reads OK on a pure tone, and the output is limited to the value set by the power control. What is surprising is that it can read much higher when transmitting actual modulated signal, and you can vary this level by varying the audio input level. Perhaps is displaying PEP rather than average power. But I would have expected that if I set the power control to 5W the K3 meter would continue to show 5W whatever the input signal, when in fact it can show a lot more.

If I first set the input level using a pure tone and increase the drive until I get just 5W then when I send a modulated signal the external power meter hovers around 2.5-3W, which is as you would expect, but the K3 meter is still showing about 5W. And the K3 meter reading can be increased still further by increasing the drive level, which is not as I would expect. It is as if the ALC is not working to limit the power. I know it won't help the linearity but that is beside the point in this context. If you set the power control to 5W you don't expect to see the meter showing 10W.