At 07:28 AM 10/15/2012, Edward R Cole wrote: >Looking into refining my use of the LP-Pan on the 1st IF of the >K3. One artifact is that the spectrum of the IF has a gain dip at >the center frequency which apparently is due to interaction of the >2.8 KHz roofing filter that is also loading the IF. > >I am wondering if I might be able to program the K3 to use an open >xtal filter position when I am using the LP-Pan? I do not use any >of the K3 beyond the IF so loss of use is not an issue; all signal >processing is via the LP-Pan and a Delta44 soundcard to the sw >running in my computer. I might have to add a resistor to provide >proper impedance loading for proper gain levels to appear at the IF output. > >The dip in gain of the spectrum makes that frequency unusable in my >application so looking for solutions (that are not invasive to the >radio). One option is inserting a pin diode switch to isolate the >roofing filter bank but that requires some RF designing and precise >surgery on the RF board. > >73, Ed - KL7UW
Found the solution. Page 46 of the K3 manual: Enabling Receive Filters. I added FL3 for the DATA-A mode. So now I can switch between FL2 - 2.8 KHz or FL3 - no filter, as desired. Testing with FL3 selected, I no longer see a gain dip in the center of the spectrum display of the LP-Pan output. My guess it does not affect Tx filter which should be FL2. I kept FL3 open for adding future filters: FL1 - 13 KHz, FL2 - 2.8 KHz, and FL4 - 400Hz. FL5 is also vacant. In the sub-RX only FL2 - 2.8 KHz is filled. 73, Ed - KL7UW ______________________________________________________________ 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
