This is what happens when I read the manual. It usually results in more questions! I'll start out with trying to understand how the filters work on my KX3.
My KX3 already had the Elecraft® KX3 KXFL3 Roofing Dual-Bandwidth Filter option installed when I bought it used 4 years ago.
The KXFL3 is a high-performance, narrow-band analog filter module that helps reject strong signals that could cause receiver blocking (desense) or intermodulation distortion. It adds two additional bandwidths to the KX3 that are automatically selected as the receive bandwidth is adjusted.
View Quote
The way I've always used filters is just cranking down the receive Pass Band Tuning from max wide to narrow enough to mask out any interfering signal.
My questions are:
Why are these called "Roofing Filters"?
Are they used for specific modes, or anywhere (SSB, Digital, CW) there are interfering signals?
Why are there XFIL (Extended Filtering) FL1-FL5 on the display, when I've only ever noticed FL1-FL3 being selected?
Is there a better way to use the filters? PBT I = wide to narrow, PBT II shifts from side to side?