OK, if you're talking about CW, the K3's normal CW is on lower sideband.
In CW the filter behaviour gets tangled up with the sidetone pitch setting, which is also the default FC (centre frequency) for the filters in CW mode. Suppose the sidetone pitch/FC is 500 Hz and the BW (bandwidth) is 2000 Hz. Given those numbers, the calculated hi-cut and lo-cut frequencies would be 1500 Hz (FC + BW/2) and -500 Hz (FC - BW/2). That's a minus sign on the lo-cut frequency, meaning it's on the other sideband. The firmware should not allow that; it needs to place the lo-cut frequency on the proper sideband far enough above zero to give adequate carrier and opposite sideband suppression. IIRC, the low-pass cutoff is adjustable in the latest firmware - I believe it can be set to 100 Hz, 200 Hz or 300 Hz.
So, with the low-pass cutoff set at 200 Hz, FC at 500 Hz and BW at 2000 Hz, the actual filter bandpass will be from 200 Hz to 1500 Hz. Adjusting the Width control would only affect the upper limit, as the lower limit is fixed by the low-pass cutoff. If the Width setting is sufficiently narrow for the calculated lo-cut frequency to be at or above the low-pass cutoff (100, 200 or 300 Hz), the effect of the Width control becomes symmetric about the centre frequency, as you might have originally expected.
Because CW is on the lower sideband, adjusting the Width control only affects the lower RF (=higher audio) edge of the bandpass - the upper edge is fixed by the low-pass cutoff.
Does this help make sense of your observations? 73, Rich VE3KI AA0AA wrote:
Sorry Bill and all--I was describing the behavior when on CW.=A0 I more oft= en use these adjustments on CW, but if it is important for understanding th= e question (and for me to understand what's going on!) I will check with SS= B when I get home this evening.
______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
