[GreenKeys] Terminal unit (HAL ST-5000) adjustment

[Ethan Blanton]

Jeffrey Angus wrote:
> On 1/7/18 7:26 PM, Ethan Blanton wrote:
> > Furthermore, a 'scope on the ST-5000 showed greatly unbalanced
> > mark and space amplitudes, rather wide ellipses on the cross, and
> > an angle between the ellipse long axes of probably 15 degrees off
> > perpendicular.  The needle bounced significantly on a known good
> > (i.e., generated locally on a computer with a high quality sound
> > card) signal.
> The wide ellipses are normal

Excellent to know.

> The unbalance is likely from not having the 2B pass band properly
> centered for the two tones.

The unbalanced deflection persisted when supplied from a local,
symmetric audio source, and I adjusted it out with the "space balance"
trimmer.

> And lastly, the 15 degree offset is from people running 200 Hz
> shift instead of 170 Hz.

Ah hah!  My local audio source was indeed much closer to perpendicular
than some of the signals I was copying off-air (though still not quite
perpendicular before adjustment), that would explain their significant
skew.

Thanks for your input!

Ethan