Dave, The K3 provides two alternatives to turning off AGC in this situation. We closely examined the effect of these on multiple close-spaced signals, and both reduce IMD considerably:
1. CONFIG:AGC DCY sets the AGC decay characteristic, and applies to both AGC-S and AGC-F (slow and fast AGC). The default setting NOR, provides a traditional linear decay. The SOFT setting applies a "soft" exponential decay. It typically reduces in-band IMD by 10-15 dB. 1. CONFIG:AGC HLD adds a "hold" timer to slow AGC-S (slow AGC) only. It behaves as if you were manually (and very quickly) riding the RF GAIN control, reducing gain when a very strong signal comes in, then turning it back up N seconds later. The normal setting is 0.00 (no hold time); a typical setting for pileup conditions might be 0.40. This can reduce in-band IMD as much as turning AGC off. Please give these AGC alternatives a try. 73, Wayne N6KR On May 31, 2011, at 1:42 PM, Dave Hachadorian wrote: > The KE7X Guide has an interesting discussion about the > shortcomings of the K3's AGC in a CW pileup situation. I have > complained about this AGC issue several times, but there has not > yet been any effective solution. > > The K3's AGC, even at SLP=0 and THR=8, compresses CW signals at > too low a threshold and too flat a slope. Signals in a pileup > are all mushed together by the AGC. It's not an IMD problem, > it's a compression problem. The usual solution, turning AGC OFF, > is thwarted by the AF Limiter's extreme distortion on even > moderately loud signals, even at its max setting AF LIM = 030. > > If you have extremely sensitive headphones, and a very quiet > shack, you can turn AGC OFF and turn the overall receiver gain > down to where the AF Limiter rarely triggers, but one shouldn't > have to jump through these fiery hoops. With a TS-850, you could > turn AGC OFF, and a loud signal would not blow your ears off, and > would not be severely distorted. If they could do that in 1989, > it should be doable today. > > > Dave Hachadorian, K6LL > Yuma, AZ > > > > -----Original Message----- > From: T Gahagan > Sent: Tuesday, May 31, 2011 12:06 PM > To: Elecraft List > Subject: [Elecraft] New K3 guide by KE7X > > For those that don’t know about the new K3 guide by KE7X check > out the link in this message. Fred has done an outstanding job > of explaining many of the intricacies of the K3 that have puzzled > me. Block diagrams and step by step instructions on just about > every facet of operation are really helpful. Fred’s guide doesn’t > replace the K3 manual by any means but it sure has helped me > determine if I have my K3 set up properly for what I am trying to > accomplish. I have no financial interest in this product but > thought reflector members might like to know about this new > offering. > > Todd, WA7U > > > > http://www.ke7x.com/home/guide-to-the-k3 > ______________________________________________________________ > 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 > > ______________________________________________________________ > 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 ______________________________________________________________ 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
