This "Duhing" is entirely unfair. Didn't you read what he said? The author stated that he had the pre-amp off, RF gain at minimum, NB off, NR off and ATTN turned on. What more could he do to eliminate the overload? Without looking, I believe the MDS of the K3 and the FT-817 are probably similar on 60 meters. I believe he did everything possible with his settings. I still believe the problem could be the switching diodes producing IMD from that super strong signal and there may not be an easy cure. Steve Ellington [email protected] ----- Original Message ----- From: "Jim Brown" <[email protected]> To: <[email protected]> Sent: Monday, May 04, 2009 1:01 PM Subject: Re: [Elecraft] K3 on-channel strong signal overload?
> On Sun, 3 May 2009 21:39:55 -0700 (PDT), orbarrett wrote: > >>I was joined while ragchewing with some friends on 5371.5 >>by two other friends locally, one operating HF mobile from the same >>driveway >>and another operating from a base rig in the shack (using a backyard >>dipole >>antenna). When either of these two friends transmitted on the same >>channel >>(at 100W), I observed severe signal breakup in the K3 receive audio. > Why are you surprised by this? This is entirely normal > >>To investigate further, I switched the portable antenna from the K3 to my >>friend's FT-817 on the same operating table, and no audio breakup was >>observed under the same conditions. Returning the antenna to the K3, I >>then >>got rid of most of the signal breakup by turning on the input attenuator >>and >>turning down the RF gain to near minimum. > > DUH! Why are you surprised by this? You had the K3 set for maximum > sensitivity and then hit it with a 100 watt transmitter. OF COURSE it's > going > to overload! You probably had the preamp on too, which is entirely un- > necessary on 60M. The 817 is probably a much less sensitive radio, and > may > have a more brute force AGC. The K3 will outperform it by 40-50 dB in > rejecting signals outside its passband. > > The K3 is doing exactly what you SET its controls to do -- pull very weak > signals out of the mud. NO radio has infinite dynamic range. If you set it > to > perform well on weak signals (preamp on, attenuator off, RF gain all the > way > up), it's going to be badly overloaded by 100 watts ON FREQUENCY from an > antenna 30 feet away. > > These are fundamental concepts of radio. It's too bad that they are seldom > taught today. Most of us old farts learned them as Novices when we put our > first rigs on the air. In those days, there were no transceivers. You had > a > transmitter and you had a receiver, and when you transmitted your receiver > overloaded. > > 73, > > Jim Brown K9YC > > > ______________________________________________________________ > 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
