Thanks for the useful info. I’ll save this one…. and the Brown article too…
David, K5HEC > On Mar 28, 2020, at 2:01 PM, Mark Janzer via BVARC <[email protected]> wrote: > > Local shop, JPM Supply (google it) has 240-43 toroids for $8.50 each. Orders > arrive in my mailbox in a day or two. > > 73 > Mark > K5MGJ > >> On Mar 27, 2020, at 5:12 PM, Rick Hiller via BVARC <[email protected]> wrote: >> >> >> Tell you what I would do, Marty......Get you some T-200-43 torroids and >> wind your coax thru these a few times at about 35 feet below the feed point. >> Then I would also do the same, or make a 10" dia coil of 8 or so turns of >> coax on a form right where the coax enters into the shack. Further details >> on this have a read of Jim Browns article -- ' >> http://www.w4ava.org/articles/k9yc-rfi.pdf >> <http://www.w4ava.org/articles/k9yc-rfi.pdf> >> >> This antenna will certainly generate common mode currents on the feed line. >> And whether they use that to accentuate the performance or not, these >> currents will cause you problems in the shack. >> >> Certainly try to get the antenna up to 35 feet or so. By doing so also >> gets you above the buildings and noise, etc. And most important, it will >> see the horizon in a single story house neighborhood. I had a 40 meter >> ground plane vertical up at about 40 feet years back and it worked >> gangbusters. >> >> There is alot of information on the web about this antenna..... or really >> about the Comet, Diamond or Eagle versions of this design. MFJ licenses the >> design and manufacturing from Comet. Google "N6PET Comet Antenna CHA-250". >> He describes what is inside the matching xfmr and his take on performance. >> Even Monitoring Times got into the picture with a comparison review with the >> GAP Titan. Gooogle that too. >> >> On the higher bands it might do OK, especially if you get it higher in the >> air. But not on the lower bands 40 and below.... just because it is quite a >> compromise -- on 80 it is about 35 electrical degrees long. About 1/3 a >> full size 1/4 wl vertical . On receive it probably does OK. Heck 3 foot >> long active antenna out performs long wires on receive. Transmit is a >> different story. Maybe a 40 and 80 dipole will get you better results and >> again depends on how high above ground it is.. >> >> I wouldn't stop using it. Just improve the performance by getting it higher >> in the air and choking the coax appropriately, to eliminate RF in the shack. >> And run 250 watts into it if you can. It'll take it and that will improve >> your radiation strength. >> >> GL and 73...Rick -- W5R >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> >> Virus-free. www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> >> <x-msg://2/#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> On Fri, Mar 27, 2020 at 3:42 PM Neal Naumann via BVARC <[email protected] >> <mailto:[email protected]>> wrote: >> Hmmm... MFJ doesn't shed much light on what is in the "matching section". >> Hopefully, it's not a 50 ohm resistor! Maybe it is a 9:1 balun and this is >> like an end-fed wire. But then there is this from the manual "Raise the >> antenna and mast assembly up and mount in the final position. For best >> operation it is recommended that the antenna be put up about 35 >> feet in the air although reasonable results are obtained with a lower >> height". So they are hoping to use the mast as part of the radiator...The >> other problem is that you would like to operate on 80 meters and only have >> 28 feet of antenna. So, I'm not sure where I'm going here with your >> problem. Maybe something in breaking down and arcing in that "matching >> section". If it's a 9:1 balun...that might be why it's only rated at 150 >> Watts CW? >> >> Neal N5EN >> >> On Fri, Mar 27, 2020 at 11:21 AM Martin Blaise <[email protected] >> <mailto:[email protected]>> wrote: >> I have a mfj 2386 vertical at my house . It receives okay but transmit is >> questionable at best. I contacted mfj and asked how to add radials and they >> said that antenna is designed for without verticals and did I have the >> bottom of the antenna at 37 feet up? I only have it about less than half of >> that. I need a taller support. Anyway it’s broadbanded and my 450d internal >> antenna tuner shows good swr match but last night on 80 meters I tuned up >> and the antenna matched fine but when I transmitted on cw with flidigi it >> showed swr mismatch. Rf in the shack? Trouble shooting ideas? Thanks >> ______________________________________________________________ >> NARS mailing list >> Home: http://mailman.qth.net/mailman/listinfo/nars >> <http://mailman.qth.net/mailman/listinfo/nars> >> Help: http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm> >> Post: mailto:[email protected] <mailto:[email protected]> >> >> This list hosted by: http://www.qsl.net <http://www.qsl.net/> >> Please help support this email list: http://www.qsl.net/donate.html >> <http://www.qsl.net/donate.html>________________________________________________ >> Brazos Valley Amateur Radio Club >> >> BVARC mailing list >> [email protected] <mailto:[email protected]> >> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org >> <http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org> >> >> >> -- >> Rick Hiller >> e-mail: [email protected] <mailto:[email protected]> >> Cell: 832-474-3713 >> Physical: 9031 Troulon Drive >> Houston, TX 77036 >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> >> Virus-free. www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> >> >> <x-msg://2/#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>________________________________________________ >> Brazos Valley Amateur Radio Club >> >> BVARC mailing list >> [email protected] >> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
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