Holy cow 10T? Thats a big chunk of iron. Kinda surprised you had enough cable length for that... :)
On Sun, 2009-07-19 at 15:01 -0400, Paul Christensen wrote: > Problem solved. The RS232-to-USB adapter between the K3 and PC is > responsible for 100% of the noise. I now recall running into this issue > before with the Elecraft USB adapter used on my LP-100 wattmeter. 10T > through a #31 Fair-Rite toroid cleaned it up completely. > > Paul, W9AC > > ----- Original Message ----- > From: "Paul Christensen" <[email protected]> > To: <[email protected]> > Sent: Sunday, July 19, 2009 2:15 PM > Subject: [Elecraft] K3 Noise Floor 160m - 75m > > > >I was recently looking at the noise floor of my K3 with SDR-IQ with antenna > > disconnected. As I went from the upper bands down to 75m and 160m, I > > noticed that the noise floor was not particularly clean on some portions > > of > > the low bands. I have attached links to two print-screen shots of what I > > am > > referring to. In both cases, the antenna is disconnected and the pre-amp > > is > > engaged. I can hear the high noise floor as well as see it on the SDR-IQ > > screen, even with the SDR-IQ disconnected. A few more important points: > > > > 1) The radio is not being coupled to a nearby magnetic field. The shots > > taken are isolated from the radio shack and the rig is battery-powered as > > is > > the laptop PC. Same result when the rig is in the shack and connected to > > a > > desktop PC; > > > > 2) The result is the same if I toggle the ANT2 port with no antenna > > attached.; > > > > 3) Although I am sampling the IF with the SDR-IQ, the noise floor remains > > with the SDR-IQ completely disconnected from the K3. The only relevant > > mod > > is the change to the IF voltage divider as described by N8LP; and > > > > 4) With the pre-amp disengaged, the noise floor drops as expected, but the > > noise floor rise as shown in the screen capture is still evident. > > > > In the first link, I have captured the effect on the upper end of 75m. > > Notice that the broadband noise bump is generally just outside the band > > but > > even so, the noise floor is noticeably higher than when measured down > > toward > > 80m as shown in the second link: > > > > http://tinyurl.com/ltyc2o > > > > Down toward 80m... > > > > http://tinyurl.com/kpxhgb > > > > I can replicate this on 160m as well. All other bands are clean. Can > > someone confirm this effect by using their K3 (with N8LP buffer mod) and > > SDR-IQ unit and get back to me by private E-mail? Thanks! > > > > Paul, W9AC > > > > ______________________________________________________________ > > 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
