The "anomaly" is not really an anomaly, it is just the other side of the down conversion oscillator. For a filter to pass an SSB audio signal the passband needs to go down to 300Hz or so. For this to happen the attenuation for 0Hz and image frequencies can't be that far down. That is all it is though it is probably better with the 8 pole filter. It can also be eliminated by raising the centre frequency, at the expense of bass response. Unfortunately I don't think you can do this on transmit, though perhaps you could adjust your filter offset. That would not work with the USB/LSB inversion below/above 8MHz.
Currently the filter is centred on 1.5kHz by default. The best place for it but if you narrow it down with DSP it is probably better to raise this to 1.8kHz. I am not sure how the filter shift relates to the DSP filter and the crystal filter, i.e. which is adjusted, probably both. However, I find I always need to reduce the filter centre frequency to maintain intelligibility as I narrow the DSP bandwidth. So to make sense of a signal within 1.8kHz I need a 1kHz centre frequency. That is not what I would expect which makes me wonder what the shift control actually does. Mike -- View this message in context: http://n2.nabble.com/K3-Filter-response-tp2191015p2191674.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
