[Elecraft] K3 QSK artefact

[David Cutter]

This is a re-post to see if it attracts comment.

This concerns an audible artefact using QSK cw mode.  When either rf gain or af gain are at maximum, there is an additional noise which accompanies the Morse characters.  This can be demonstrated as follows:

Mode: QSK cw, paddle sending string of dots or dashes ANY speed
power o/p: any, ie nil to max, dummy load or antenna, agc on or off,
filter: any, but more pronounced >1kHz
listening to monitor (side tone) on phones or speaker at ANY monitor setting

audio control: max
rf control: start low and raise until the artefact appears

or

rf: max
audio: low and raise until the artefact appears

at low speed the artefact sounds like a scraping noise riding on the string. 
High speed it's like an extra edge.

The effect is also present with monitor at zero.  In this condition, the artefact itself can be heard without tone from the Morse characters:
a rushing sound is heard.  At a guess I would say it is digitally induced 
noise.

This effect makes my K3 unusable on QSK, but does not occur on semi bk-in.  Anyone else heard this?  I think there must be a fault on my K3.  Please note, this is not receiver or band noise which is a long way down on this artefact.


David
G3UNA
K3 #547