A noise level of -140 dBm is reasonable with no antenna connected or a quiet band. It also depends on the span and how you have the K3 set up. On mine, the noise level is around -160 dBm with no antenna connected to the K3, the K3 preamp turned on, and the span set to 2 kHz. If I turn off the preamp, turn on the attenuator, and set the span to 200 kHz, the noise level is a little below -120 dBm. With an antenna connected it is higher than that.
You can get an idea if everything is working right by comparing the K3 S-meter reading of a signal within the receive passband. S9 should show as roughly -73 dBm on the P3 display and change by 6 dB per S-unit below that. There's a table of dBm levels versus S-units in the latest P3 manual. Alan N1AL On Fri, 2010-10-29 at 11:38 -0700, David Yarnes wrote: > I may need some assistance on how my P3 should act. My P3 > arrived while I was away on an extended trip to the > Northwest. I now have it up and running, but I have some > questions. I've perused the manual, including the newer > version on the website. It seems that my levels may be > wrong, but not sure. > > Here's what I have done--I updated my K3 firmware to the > latest version on the website. I also updated the P3 > firmware. I also had to make the mod to my K3 (#96) for the > I.F. output gain. Prior to making that modification, the > noise level seemed to be around -110 dbm, but that was also > before I updated my K3 firmware also. > > Now, I seem to have a reference level way down to > around -140 dbm. I do see signal spikes, but it seems to > take an S8 or S9 signal to really show on my screen (to > differentiate them from just noise), which I assume is > indicative of my noise floor. None of the illustrations in > the manual show something starting that low. It makes me > wonder if I did the K3 mod properly. I did replace the SMT > part with the supplied SMT device (or think I did!). > Hopefully I didn't screw that up. > > All of this scaling varies from band to band somewhat, but > it's always -120 dbm or lower. I see nice spikes from > stronger signals, but some that are quite copiable on the K3 > don't seem to make much of a spike at all. The waterfall > does seem to show the signal better in those cases. I'm > assuming it's just because those signals are right at the > noise level, but I was primarily concerned about the fact > that my setting has to be so much lower (higher numberical > value of "minus" dbm) than anything shown in the manual. > > Dave W7AQK > > > > ______________________________________________________________ > 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
