I also use the 7 band Buckmaster OCF antenna. My config is the long leg is East/West and 80' on one end and about 50 on the other (also sloping property). The short leg is at a right angle and is about 50' on one end and probably 30 on the other. It's fed with about 30' of coax.
It's a fantastic antenna and I can work coast to coast QRP. It also works DX nicely and I've worked Antarctica, NZ, etc. I think I'm up to 185 countries now QRP. Steve W1SFR Kx3helper.com Sent from my iPad > On Jan 11, 2014, at 1:50 PM, Barry LaZar <k3...@comcast.net> wrote: > > Doug, > Nice write up. > Other Readers, > I'd like to make a comment about the antenna as I know more than just a > little about the things. An off center fed, OCF, dipole is not a magic > antenna as some hams have come to believe. They are just a good wire antenna > that is fed in a way to make them appear to have a 50 Ohm impedance. They are > based on the 1/2 wave dipole which only has a workable impedance at 1/2 wave. > At even multiples of a 1/2 wave, the antenna exhibits a high impendance which > most radios do not like. So, way back in radio history a smart guy said if I > don't feed the dipole in the center I can find a spot that looks like 300 > Ohms and use a transformer to make it look like 50 Ohms over several bands. > When he invented that antenna, the only odd band was 15 meters. What that > meant was that if you created an 80 meter OCF dipole, you could use it on 40, > 20, and 10 meters, without a tuner. > > The basic 1/2 wave dipole antenna can be awesome if hung up at some > reasonable height. When fed in the center it is going to have a very high > SWR, which means you need to be careful of transmission line loss and have > some way to deal with the SWR. Open wire feeders handle the loss issue and a > very good tuner does the rest. Or you go to the OCF dipole and use a 6:1 > CURRENT balun or balun and line isolator. > > When a dipole is operated at multiples of a 1/2 wave you can actually > develops gain in the plane of the antenna. How much gain and lobe direction > is a function of how many 1/2 waves the antenna is. > > Those of you who want a good basic antenna and don't want to spent a lot > and can get it up about 30-35 feet or higher go for the OCF dipole. I think > you'll be happy. I have one up in my yard at about 40' on one end and about > 35 on the other( it has to do with the slope of the land) and, as Doug, I > work out everywhere. There are several sources for the basic OCF antenna and > a source for a variant that I run. However, building one is a snap. Just go > to Home Depot and buy 135' of #12 stranded insolated house wire ( color is > unimportant ) have it cut such that the cut is about a 1/3 of the way off an > end. Pick up some insulators at a hamfest and order either a 4:1 or 6:1 > CURRENT balun. feed the beast with some low loss or reasonable loss cable, > and then sit back and have fun. I would expect DXCC in 30 days, band > conditions being good. > > Some final comments. I use #12 insulated, stranded wire just for the extra > strength. I don't want to be puting up a new antenna every time we have high > winds or ice. You could use #14 which most use, but like I said I don't want > to have to re-install my antenna. You will need an antenna tuner, but that is > OK as you will now be able to use the antenna on all bands 80-10. Lastly, if > you don't have 135' feed of horizontal space you could bend the ends down to > fit if it represents a minor portion of the antenna Or you could build a 40 > meter version using 66' of wire and just not work 80 effectively; I can > actually get mine to tune on 80, but it isn't great. > > 73, > Barry > K3NDM > > > > > >> On 1/11/2014 12:34 PM, Doug Ellmore Sr. wrote: >> I saw some discussions on OCFS. I thought I would share my setup. >> >> I worked 160+ countries with a Buckmaster 8 band OCF QRP. K3NDM and N3HU >> have observed its operation with my former ICOM 703, K3 and KX3. >> >> I think Buckmaster uses a 6:1 balun. I have my feedpoint at the peak of my >> house about 34' fed with 60' LMR400. The feedline drops down the roof 45 >> deg then perpindicular to the ground. It is connected to a static arrestor >> before being fed back up to the 2nd floor shack. The long leg is supported >> by a 14' 4x4 support north of my house but far enough away with a rope the >> the end is 18-20' above the ground. The short leg is supported by a tree >> up ~20' up SSE of the house. >> >> I used the internal tuner to tweak swr, but have also used the kx3 & >> SB-200 to get 200 watts with no tuner with no problems. >> >> Check the specs on the Buckmaster, it might help those trying the OCF setup. >> >> A north to south orientation seems to help me work good dx from Maryland. >> >> 73, >> >> Doug, NA1DX >> ______________________________________________________________ >> 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 > > ______________________________________________________________ > 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 ______________________________________________________________ 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
