Pete, The first thing I would do is get a calibrated signal generator (the XG-2 is fine if you don't have something more complex) and perform the RF gain calibration in the K3 Utility. Follow that with an S- Meter calibration. After calibration with S9 = 50 uV (-73 dBm), I see no S-meter activity with a dummy load or antenna on a "dead band." The P3 shows the noise floor between -140 and -145 dBm (2 to 3 S units BELOW S0) with a dummy load and around -130 dBm (still less than S0) with my low Windom and no preamp on 20 meters.
Second, your AF Gain may be a bit high ... mine is normally around 9 - 10 o'clock with the Sony bookshelf speakers or the CM-500 and around 10 - 11 o'clock with the Heil Proset. That represents a comfortable listening level for most signals and provides almost no noise with the antenna on 20 (160/80/40 are a different story) and quiet with the dummy load/no antenna. As a reference point, the "no antenna" noise is noticeable at full RF/AF gain and the 20 meter antenna noise is at the threshold of becoming uncomfortable at full AF/RF gain. Note, I generally do not need the preamp even with a poor antenna except on 6/10/12 meters and always use ATT on 160/80. I am not using the default settings for ACG threshold and slope ... I prefer setting both to "8" which provides for a higher threshold before the onset of AGC and less flatness after AGC begins. For an excellent look at the K3 AGC behavior see Jack Smith's (W8OZA) work: http://www.cliftonlaboratories.com/elecraft_k3_agc_and_s-meter.htm . 73, ... Joe, W4TV On 8/28/2010 6:18 AM, Pete Smith wrote: > Ever since I got my K3, I have been a little surprised at what seems to > be a relatively high noise level with no antenna connected (or on a > dummy load). Very unscientifically described, on 20m it registers 1-2 > bars on the S meter, and the background is quite loud on the speaker > with the audio gain set at 12 o'clock (RF gain full, AGC - fast, > bandwidth 200Hz with a 500 Hz roofing filter in, no noise blanker or > noise reduction). > > The radio seems to perform fine, and I have not had the feeling that I > was missing many signals because they were being masked by receiver > noise. Nonetheless, I wonder how this compares with others' experience, > or with the factory expectation? > > 73, Pete N4ZR > > The World Contest Station Database, updated daily at www.conteststations.com > The Reverse Beacon Network at http://reversebeacon.net, blog at > reversebeacon.blogspot.com, > spots at telnet.reversebeacon.net, port 7000 > > ______________________________________________________________ > 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
