Brian A wrote: > You are totally WRONG if you truly believe that the other station KHz > away is at fault because he captures your AGC when you're using a 3 > KHz filter. As you point out PSK is only 31 HZ wide. Thus it only > seems reasonable to try and copy them with a narrow filter. A filter > of 2x to 3x tx bandwidth will capture all of the signal. Note this > filter must be within the AGC loop or you must turn the AGC off and > use the RF gain control to avoid distortion. External audio filters > and may 'DSP' filter rigs are outside of the AGC loop. Get a 200Hz IF > filter any you will be pleasantly surprised how many of the so > called problems disappear.
Exactly right. Sometimes I call CQ and at first do not see (or hear) anyone coming back to my call. Then I kick in my cascaded 250hz filters, and suddenly there is a readable signal that was not readable without the filter due to some strong adjacent signal or other that had been de-sensing my receiver's AGC. Narrow filters are a must for effective PSK operations. Asking everyone to operate QRP so that no one's signal is strong is simply absurd; it is not the answer. What about my locals, who run around 50 watts and are still S9+20? Am I supposed to expect them to operate at 1 watt? Of course not. Those who operate solely with a 3 Khz passband on PSK are going to experience very poor operating results and no help for it. de Roger W6VZV
