> More generally, the APF proponents seem to have the problem that they treat it almost as magic. If they could characterise what it does in terms of filtering, AF gain adjustment, distortion etc. it should be possible to simulate it in DSP, subject only to having enough processing power. In particular, peaking just seems to me to mean turning up the AF gain in parallel with reducing the bandwidth. If that is all that it is doing, and if the K3 has soft AF gain controls, a plugin box could issue both commands in parallel.
The circuit in question is on page 54 of the FT1000 schematic below: <http://www.radioamateur.eu/schemi/FT1000_user.pdf>http://www.radioamateur.eu/schemi/FT1000_user.pdf The APF is around Q3016-2 (including Rs 3062, 3065, 3067 per the "un-modification" sheet on N1EU's website below). The circuit schematic above has *not* been modified to the (incorrect) values shown in the Yaesu service bulletin. http://n1eu.com/Mods/apf.pdf The FT-1000's APF is generally regarded by many as the best APF ever done. It should be possible to plug this into a circuit simulator and generate a frequency response plot that Lyle can emulate in the DSP. I have a feeling that this is a very narrow and high-Q response that is on the verge of ringing, but it should be possible to duplicate the circuit in the DSP. 73, Bill W4ZV ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html