[RTTY] K3S with AFSK

[Jim N7US]

I'm replacing my K3 with a K3S and plan to use AFSK (using the internal
soundcard) after using only FSK for many years.

I prefer listening to low tones, 1225/1445.  I understand that high tones
are recommended for AFSK to prevent the possibility of transmitting the
second harmonic.

My questions are K3/K3S specific:

1) Are low tones OK?

2) Can/should the AFSK TX 400-Hz DSP transmit audio filter, which is
selected in the K3's configuration?  A friend just got his K3S and turning
on the filter apparently prevented the AFSK transmission, which leads me to
conclude the filter is designed for high tones.

I use DXLab with WinWarbler as my general logger, which can use only MMTTY
to transmit RTTY.  I understand that it's good to set MMTTY taps to 512 to
transmit a narrow signal, so I'll do that.  I'll also consider transmitting
AFSK with 2Tone when using N1MM+.

Any other suggestions?

Thanks very much. 

73, Jim N7US