Thanks Skip, I had a K1FO design 2M beam but took it apart , too big for me. I also have old large 2M and 440 cross polarized Yagis laying in the garage doing nothing , but again too much antenna for my back yard these days. Your SS5 skeleton-slot beam is a clever design. What is the actual function of the horizontal sections across each loop? Also, in my quick read, I did not find the over dimensions of each loop. Did I miss it?
Andy On Mon, May 25, 2009 at 7:28 PM, kh6ty <kh...@comcast.net> wrote: > > > Hi Andy, > > I operate 2 meters and 70 cm every day from here in Mount Pleasant. You > really need 14 dBi of antenna gain on 2 meters and 17 dBi on 70 cm to > reach 200 miles on phone if there is no propagation enhancement. A > log-periodic will probably not have enough gain on any one of the bands > it covers. Using DominoEx 4 (not critical for tuning) will get you > farther, but there are not many people to talk to yet. Almost all 2 > meter QSO's are on phone, with CW used when phone cannot make it. The > biggest VHF contest of the year is the June VHF QSO Party, June 13 to > June 15, because there is more chance for tropospheric ducting during > the summer. This is the best time to find someone on the air. At other > times, check the APRS propagation map at > http://www.mountainlake.k12.mn.us/ham/aprs/path.cgi?map=na for > propagation in your area. Even if you are not ready for the June > contest, get up whatever you can and you will probably find activity. > The calling frequency for 2 meter phone is 144.2 and for 70 CM phone it > is 432.1. > > Most 70cm QSO are coordinated on 2 meters first, so that the beam > heading is already set, so align your 70 cm beam and 2 meter beam > carefully in the same direction. You generally need 3 to 6 dB more gain > on 70cm than you have on 2 meters, but the antennas are 1/3 the size of > a 2 meter antenna, so if the boom lengths are equal, you should be OK. > > Check out my FM DXing presentation I made at the Southeastern VHF > Society conference at Charlotte, NC, in April for other ideas. That link > is also on my web page. > > If you want a medium gain antenna for 70 cm that you can easily > homebrew, consider my SS5 skeleton-slot beam: > > http://home.comcast.net/~kh6ty/site/ and click on the SS5 link. Two or > four of these stacked will give you enough gain to reach 200 miles or > more if there is no ducting. When there is an opening, one of these > antennas will get you 200 to 300 miles. > > For 2 meters, you can homebrew a cubical quad like the 12-element > cubical quad that apparently was published in CQ Magazine. The > dimentions are in the MMANA-GAL VHF ANT folder. You need MMANA-GAL > http://mmhamsoft.amateur-radio.ca/mmana/ to display the beam dimensions. > > To work 2 meters and 70 cm with a common feedline, many people use a > diplexer. You would probably want to have a separate feedline for 6 > meters, and your transceiver may use a common antenna connector for 2 > meters and 70 cm, but perhaps a different one (together with HF) for 6 > meters. > > The best commercial antennas for 2 meters and 70 cm are probably the > K1FO designs sold by Directive Systems: http://directivesystems.com/ > > Be sure to use low loss feedline for long runs, like hardline (the > lowest loss), or RG-8, especially on 70 CM, unless your runs are very > short, and at least RG-8 on 70 CM. > > WSJT is also a digital mode, and with 100 watts and a long yagi, you can > also try EME on the rising moon using WSJT. > > The challenges for VHF/UHF DX are quite different from those on HF, but > lots of fun in a different way. Signals, except during a 6 meter > opening, are generally truly "weak signals"! You need all the antenna > gain you can get, and will always wish for even more! > > I host a 2 meter DominoEX 8 net, using FM (and horizontally-polarized > antennas) twice a week and we have had checkins by stations with long > yagis from as far away as 200 miles. > > Everyone uses horizontally-polarized antennas. > > These opinions are based on my own rather recent excursions into VHF/UHF > over the past two years- others may vary. > > 73, Skip KH6TY > > Andrew O'Brien wrote: >> >> >> I am tempted to try get active on 6M-70cm for digital modes and CW >> this summer. I am looking to avoid multiple runs of coax and thought >> of a homebrewed log periodic for these bands, using one feedline . >> Does anyone here use one, or have favorite software for log periodic >> design? Is the range too great? Any commercial ones? >> >> Andy K3UK >> >> > > -- > *Skip KH6TY* > http://KH6TY.home.comcast.net >
