I think it may be due to my final comment, but first, some info. My pre-amp is off and the ATT is on 90% of the time. I seldom turn on the pre-amp. With the pre-amp off, and the ATT on, I consistently hear guys breaking in that the others in the group do not hear, and they run good equipment. They comment on it, and believe it is due to my antenna. The apex of my antenna is only 40 feet high. One of them has a 100 foot tower. I believe it is due to resonance. Read on.
I would suspect antenna not resonant, or working with a swr that is not optimum for the frequency. (You need both.) Emphasis is given to swr for transmit out of concern for the finals, but I discovered years ago how important a 1.0:1 swr is for receive. Anything less is a compromise in receive performance. You say "to 'hear' an S9 signal". That has me curious. S9 is RF, hearing is AF. Still pondering.... The K3 is calibrated for S9 at -50 uV with the pre-amp on. This may be the answer to your question. It could also be that you need to calibrate your S-meter. The XG-2 works well for that. Good luck, Rich, n0ce ----- Original Message ----- From: <k...@charter.net> To: <elecraft@mailman.qth.net> Sent: Tuesday, November 13, 2012 8:39 AM Subject: [Elecraft] K3 sensitivity below 40 meters > > Conventional wisdom historically has been that a receiver preamp is not > used at 40 meters and below primarily because it is not needed, indeed > it would typically degrade receiver performance. So why is it necessary > to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at > the appropriate level of other receivers? > ______________________________________________________________ > 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
