Jim, Per a previous recommendation from Elecraft, if you want to connect an antenna directly to the input of your P3, you should put a pair of paralleled diodes (in opposite polarity with respect to each other) across the P3 input jack to protect the P3 from a static discharge.
I have used a small single-turn magnetic loop tuned to 40 meters to help me isolate a noise source on 40m, and it worked very well. IMHO you really need a proper magnetic loop which inherently has sharp and deep nulls to be able to identify the direction from which the noise is coming. My 40 meter loop was 48" in diameter, and it worked fine without any additional preamplification. However, for the same efficiency, an 80m loop would need to be 8' in diameter which is a bit impractical to carry around. Although I haven't tried it, I'm pretty sure that a 3' or 4' diameter loop tuned to 80m would still provide enough signal for the P3 and should exhibit very sharp nulls to help you locate the noise source. One other suggestion of an antenna that would be much smaller in size, yet would still exhibit nulls is a small ferrite bar antenna similar to that which is used in broadcast band (AM) radios. However, I have no experience with that kind of receiving antenna. Good luck w/ your noise sleuthing! 73, Dale WA8SRA > I just realized I have an unused DXE RPA-1 which I could put in front of > the P3. Any thoughts on that? > > jim ab3cv > > > On Sat, May 17, 2014 at 7:47 PM, Jim Miller <j...@jtmiller.com> wrote: > >> I've pulled my P3 out of my setup to try and go searching for sources of >> 160/80m RFI. >> >> I did a whole house shutdown today and made sure that anything which had >> a >> battery was also shut down. That included the fire/burglar alarm system. >> For the purposes of these two bands my house is "clean." >> >> So now I need to do a walk around the area to see if I can locate the >> sources. >> >> I tried a little DC to daylight receiver with little success even with a >> 1ft diameter 2 turn loop for an antenna. The signals in question are too >> narrow band and the receiver is too insensitive so the signals are >> buried >> in noise. >> >> I'm now trying to use the P3 in hopes that its signal processing and >> averaging and ability to see a broader spectrum might be easier to use >> than >> listening to a single frequency. >> >> I tried the loop antenna directly into the P3 while powered on a battery >> and it seems like I could use a bit of gain to get over the input noise >> of >> the P3. >> >> Have others tried this and if so what sort of preamp, antenna or other >> setup was used? >> >> Right now focused on 160 and 80m. >> >> 73 >> >> jim ab3cv >> >> >> > ______________________________________________________________ > 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 d...@lightstream.net > ______________________________________________________________ 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
