Further, I found this reply from Wayne (back in 2014) On Oct 14, 2014, at 6:35 AM, jsdroyster at nc.rr.com wrote: > Our panadapter regularly (but not always) shows wide green bands of "noise" before the antenna is connected. When present, the bands are visible in the same panadapter screen location regardless of wbich band the radio is turned to, but the locations vary day to day (sometimes at the low end of the screen, other times in the middle). The white line on the screen rises to peaks above these green areas. Are you using a PX3 or P3? Assuming it's a PX3, try this: - make sure RX I/Q is set to ON (KX3 menu) - make sure the PX3->KX3 cables are fully seated - connect an antenna to the KX3 - switch to 20 meters - turn the preamp ON and set the PREAMP menu entry on the KX3 to 20 dB - set the PX3's SPAN to 50 kHz or lower - adjust the REF level so the "grass" (noise floor) is close to the bottom of the spectral plot With the above setup, there will typically be no visible fixed spectral lines on the PX3. As described in the PX 3 FAQ on our web site, very wide SPAN settings and low front-end gain (e.g., turning off the preamp) will reduce the signal-to-noise ratio of an RX I/Q-based pandapter, including making wideband spurs more apparent. The same limitations apply when using the KX3 (or other quadrature downconversion radio) with a PC sound card. Typically this doesn't impact usability, e.g. locating signals of interest. In fact most sound cards are limited to displaying about 48 kHz of spectrum, while the PX3 can go wider thanks to its high-performance/high-speed A-to-D converter. The P3 uses a completely different method of acquiring the signal for spectral display: It digitally down converts the K3's 8.2-MHz I.F. This provides a S/N and spur advantage over an RX I/Q approach, but requires much more complex circuitry -- hence the difference in cost between the two units. Wayne N6KR
73 from David GM4JJJ > On 9 Sep 2016, at 18:09, David Anderson via Elecraft > <elecraft@mailman.qth.net> wrote: > > You will get spikes with no antenna where they are not covered up by band > noise. Also if you have a really big spike near where you are tuning, try > turning down the NB level in THE PX3 or turn the PX3 NB OFF. > > Elecraft have explained about these spikes which are as a result of the > switched mode regulators in the PX3, but they are not a problem when you have > an antenna connected with band noise. > > Let us know how that goes. > > 73 from David GM4JJJ > >> On 9 Sep 2016, at 16:31, Larry Naumann <n...@att.net> wrote: >> >> Don >> Thanks for the suggestion but that does not fix/improve the situation. >> Looking at it further I also have spikes at roughly 23, 30 and 52Khz above >> and below my cursor. The 52 Khz signal is at S4 the other two are about S2. >> I can turn on the PX3 and look at the display with no antenna connected and >> see these spikes on every band. If I disconnect the cables to the KX3 the >> signals are still there but go down to S1 in strength. I have even tried >> running both on separate battery supplies but the problem is the same. The >> spikes are there even if I disconnect the I/Q cable but the spikes are very >> small, as soon as the I/Q cable is plugged in the spikes increase. >> Larry >> n0sa >>> On 9/9/2016 9:22 AM, Don Wilhelm wrote: >>> Larry, >>> >>> I suspect hum, buzz, and noise pickup on the RX I/Q cable shield between >>> the KX3 and the PX3. >>> Try "Bonding" - run a heavy wire or strap between the KX3 and the PX3 in >>> parallel with the RX I/Q cable. The shield from old RG-8 coax works well. >>> >>> 73, >>> Don W3FPR >>> >>>> On 9/9/2016 10:12 AM, Larry Naumann wrote: >>>> I have just recently noticed that there is a continual spike that follows >>>> my cursor. It is internally generated. In CW mode it is away from my tuned >>>> signal by the amount of my CW side tone setting and can be switched to >>>> above or below the cursor depending on if I am in CW or CW-R. >>>> These spikes occur with no antenna connected and are S4 to S5 in strength >>>> depending on band. >>>> I did the Opposite Sideband Rejection adjustment but show no improvement. >>>> I think something is either set wrong or I have an issue. >>>> Any help or ideas are appreciated. >> >> ______________________________________________________________ >> 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 >> Message delivered to gm4...@yahoo.co.uk > > ______________________________________________________________ > 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 > Message delivered to gm4...@yahoo.co.uk ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
