[Elecraft] K3 Hissy and Noisy Audio

[Paul Christensen]

> 1 and 2.  On the line output I see a little less bass than the other
> outputs
> and I would expect this since it has a transformer in line that the
> speaker
> and phone output doesn't.  In fact I don't see a change if I go crazy
> boosting RX RQ bands 1 and 2.

Jay,

Here are my SpectraPlus FFT plots for the IC-7800 (Magenta), IC-7700 (Blue), 
Ten Tec Omni VII (Red), and Elecraft K3 (Yellow).  Each plot was taken from 
the respective headphone output and the volume level adjusted in order to 
show an uncluttered overlay.

http://216.229.20.37/images/ResponsePlots.JPG

To achieve a reasonably flat low-end response on the K3 requires an FC shift 
to about 1.25 from 1.50.  But in doing so, note how the high end response is 
now limited to about 3.2 kHz (See yellow trace).

Not surprising, the IC-7700 and IC-7800 traces can be laid on top of each 
with a nearly identical response.  Both produce a response bump between 100 
Hz - 300 Hz.  The Ten Tec Omni VII produces the best overall Rx response of 
the four rigs tested.  I wish I still had the TS-870 for these tests as it 
measured ruler-flat out of the box from 30 Hz to 6 kHz.

Regarding the K3's Rx EQ, I see substantial Rx EQ changes on bands 2-8 when 
adjustments are made, but no change on band 1 when adjusted from one extreme 
to the other.  It simply has no effect.   I've tried various alternate 
settings to see if I could engage band 1 to move, but so far, no luck.  It 
doesn't bother me as I leave the EQ flat.

Paul, W9AC