A 1:1 current balun could be very useful at rejecting nearby common-mode interference. At my house, that dropped the noise floor by about 6dB.
This is a good quality balun at a fair price. It says “QRP”, but it will handle 300W at HF, 200W above 35MHz. http://www.balundesigns.com/qrp-model-1110-1-1-isolation-choke-balun-1-54-mhz/ <http://www.balundesigns.com/qrp-model-1110-1-1-isolation-choke-balun-1-54-mhz/> wunder K6WRU CM87wj http://observer.wunderwood.org/ (my blog) > On Sep 28, 2015, at 5:24 PM, Byron Servies <[email protected]> wrote: > > Sorry, I should have said "none" instead of "1:1". You don't appear to need > it. > > I also have a very compromised installation, but better now than a > dipole. And, yes, a tidy installation does us a shocking amount of > coax! > > Good luck, > > 73, Byron N6NUL > > On Mon, Sep 28, 2015 at 5:02 PM, Byron Servies <[email protected]> wrote: >> On Mon, Sep 28, 2015 at 4:37 PM, Douglas Hagerman >> <[email protected]> wrote: >> >>> >>> I have a space-limited dipole for 20 meters with drooping ends. The KAT-1 >>> tuner >>> will tune it. What I want to know is whether to use a 4:1 or 1:1 balun, or >>> no balun, >>> at the antenna. >>> >> >> Are you feeding the antenna with coax or ladder line? >> >> Even a low dipole will have a feed point impedance of roughly 75 ohm, >> so 1:1 would be fine with coax. You may want to consider a current >> choke at the feed point, but that's up to you. >> >> With 450 or 300 ohm ladder line, a 4:1 would be more appropriate to >> match the feedline to the expected impedance of the K1 input. >> >>> If the tuner reports 24 “x10” pF, is that 240 pF or 2.4 pF? A straight >>> reading >>> suggests that it’s 2.4 pF, but I don’t see how the tuner circuit can >>> provide so >>> little capacitance. But C4 (82 pF) plus C5 (150 pF) gives 232 pF which could >>> 240 pF if you include some parasitic capacitance, maybe? >> >> Xc = 1/(2 * pi * 14 x 10^6 * 240 x 10^-12) ~~ 47. >> >> So, the tuner thinks it is seeing roughly 50 + j47 and needs -47 of >> capacitance to balance it out, right? I'd go with the 1:1. > > -- > - Northern California Contest Club > - CU in the Cal QSO Party 3-4 Oct 2015 > - www.cqp.org > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
