[Elecraft] Volumn from K3S USB interface

[Richard Lamont]

On 10/01/17 00:48, Bill Frantz wrote:
> I have installed the KIO3BUPKT in my K3 and am generally quite satisfied
> with it. During the weekend RTTY contest, I noticed that I was getting
> very low audio volumes coming into my MacIntosh when the AGC was engaged
> (both in fast and slow modes). I tried to find how to adjust the volume
> in the K3S manual, but only found the procedure by reading all the
> CONFIG items in the back of the manual. The LIN OUT setting does the job.
> 
> The manual warns that values higher than 10 may result in overdrive of
> the soundcard or saturation of the KIO3’s isolation transformers. I
> found a setting of 40 seemed to work well.
> 
> Am I the only one driving the USB this hard?

No. I did some measurements and posted to this list on Nov 6, 2016.

With AGC on, and LIN OUT set to default (10), the digital level via the
USB interface was -22 dBFS (true peak).

With LIN OUT set to 40, the gain is increased by 12 dB and thus peaks to
-10 dBFS on the USB interface. This is a much more sensible level.

I don't know if this is saturating the transformers, but as I don't use
the analogue line output it doesn't matter in my case.

I don't understand why the gain structure of the rig is designed so that
have to have the output either too low on USB or so high it risks
saturating the transformers on analogue.

When operating WSJT-X, I leave LIN OUT at 10, turn AGC off and adjust
the RF gain to get the level I want.


73,
Richard G4DYA