Chris,

I see that Julian has given you some information already - the sideband reversal thing is correct.. I must ask just how much you need to move the mark frequency. If it is only a few tens of Hz, then it is simply a matter of adjusting the BFO for LSB. If it is in the range of kHz, then it is due to operating with the wrong sideband. You must adjust the mark frequency in the application to match the filter center frequency in the K2 to use narrow filters.

I highly recommend that you activate the RTTY filter set because it allows the compression to be set independently of the setting used for SSB. I usually set the RTTY FL1 filter the same as that used for SSB FL1, but also set FL2 thru FL4 to 1.0, 0.7, and 0.4 kHz with the filter center at 1000 Hz. Greater audio frequencies may exceed the K2 BFO range capability, and 1000 Hz is a compromise that is easy to remember. Tune the desired signal to 1000 Hz (with the VFO) on the waterfall display and you are ready to switch in a narrow filter when that rock-crusher comes on close to your desired signal. The same applies to all other digital modes, not just to RTTY.

73,
Don W3FPR

Chris Kantarjiev wrote:
I'm playing in the RTTY Roundup this weekend, using a simple AFSK setup
with my K2. For some reason, when operating on 15m I need to shift
the Mark frequency to get the signals to fall inside the filter.

This doesn't match up with how I understand the K2's filters to work;
I expect the center frequency of the filter to be the same regardless
of the band.

What am I misunderstanding?

73 de chris K6DBG
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