[Elecraft] K3--Too much ALC creates energy on opposite sideband?

[Fred Jensen]

Nate:

You should run your MIC gain such that you see 4 bars of ALC with the 
5th just flickering occasionally on voice peaks.  Make this adjustment 
with compression at zero.  Then, adjust the compression as desired.  I 
generally set it so that voice peaks show 10 dB compression.  The first 
4 bars on the ALC display are in fact just a VU meter.  ALC action 
begins at the 5th bar.  Elecraft transceivers set the power out with a 
closed feedback loop [PWR setting], not the MIC gain.

Driving the ALC too hard will create IMD which, among other things, will 
show up as energy on the opposite sideband.  It all happens in the RF 
chain after the DSP has generated the SSB.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 8/28/2019 9:40 AM, Nate Bargmann wrote:
> I received a note this morning advising that I should check my ALC as he
> is seeing some energy on USB when I check into a 75m voice net on LSB.
> I am using an MC-50 microphone and am running the mic gain at 35 and the
> compression at 11.  My thinking was that generating opposite sideband
> energy would be quite difficult with the K3's DSP.  Am I wrong?
>
> I'll try working with him some morning and back down the mic gain a bit
> and see what that does for him.
>
> 73, Nate, N0NB
>