I have never used a receiver with a button labeled APF, but I have used my K2 with an audio filter. It seems to me the only other characteristic of APF is that the center frequency can be changed. On the K3, we have the Dual Passband that may work in a similar manner. Set the width to the lowest value 50 Hz and turn on Dual PB and you have a wide filter with a peak at your sidetone pitch. You can change the Pitch if you wish to peak a different audio frequency, but for the life of me, I cannot imagine why anyone would want to peak any pitch other than his preferred sidetone pitch.
If you want a little more peaking, turn on NR and set it to an aggressive setting. The way NR works is that it builds a narrow filter around a signal that it thinks is a valid signal - so you have a filter at the audio pitch where you have set the VFO. Yes, the K3 is different than those receiver that have APF, but in my opinion, it accomplishes the same thing, but differently. 73, Don W3FPR On 10/24/2010 2:47 PM, Paul Christensen wrote: >> I found the APF in my Icom 7800 worthless. > Same here. Icom's implementation of APF in the '7700/'7800 is really an > "Audio Passband Filter" with low Q. It's really no different than narrowing > a DSP passband filter. > > What's unique about the FT-1000D's APF is that the Q is very high, although > its affected with APF tuning. The high Q of the circuit forms a very narrow > filter with fixed gain, and variable peaking frequency. > > Paul, W9AC > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
