[Elecraft] K3/10 Power Meter Anomaly in data mode

[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.

-----
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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