Wow, Dave! That sounds great!! Could you support a vertical 1/2 wave for 160 with a balloon? You could end -feed it at the base through a 1/4 wave of 450 ohm ladder line and it would be a FEARSOME 160 antenna! And the whole radial issue goes away!! I've operated a vertical 1/2 wave for 40m this way with GREAT success! Even added a reflector and director to make a full-size vertical 3-element yagi for 3Y0 and SE Asia on the evening 150 degree LP - Great DX antenna! Worked Bouvet first call in a HUGE east coast evening pile-up! :-)
Charlie, K4OTV -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of DAVID CUTHBERT Sent: Saturday, December 15, 2012 10:59 AM To: Michael Tope Cc: [email protected] Subject: Re: Topband: Fw: GAP VERTICAL QUESTION Mike that QTH looks alot like the Great Salt Lake of Utah where I have operated a few 160 meter 'tests running a balloon vertical. Dave WX7G On Fri, Dec 14, 2012 at 9:52 AM, Michael Tope <[email protected]> wrote: > > > On 12/13/2012 3:14 PM, Tom W8JI wrote: > >> Somehow they thought moving the feedpoint eliminated the need for >> radials with an electrically short antenna, when the real mechanism >> was a 1/2 wave vertical was converted to a 1/4 wave groundplane 1/4 >> wave above ground and it only got a tiny bit weaker. The groundplane >> still had 8 radials, but they were hundreds of feet in the air. >> >> There was some more stuff about offsetting the feedpoint in that >> handout, but nothing that remotely applied to a fractional wavelength >> vertical just sitting on the dirt with a few radials laying directly on the lawn. >> >> They got rid of lossy traps and loading coils by using even lossier >> coax and some folded wires for a loading system. >> >> This is all why, as frequency increases and the current and voltage >> moves up the antenna, the GAP on most bands isn't terribly bad. This >> also why it is a real dog of an antenna on 160 and 80, where it is >> very short electrically, has no ground system, has an exceptionally >> poor loading method, and where it folds the radiator back and forth >> which suppresses radiation resistance. >> >> This is why a ten foot mobile antenna can tie it or beat it on 160, >> and why it is reasonably on par with anything else on most bands >> above 80 meters. >> >> 73 Tom >> > > I got hold of a brand new voyager about 7 years ago. The first thing I > did was throw away all that yellow coax stuffed inside the bottom > half. The fiberglass "GAP" for the elevated feed point makes a nice > insulator for a center loading coil. Then I added some top hat wires > with dimensions per WX7G's recommendation and fed the antenna from the > bottom as a standard ground mounted vertical with a bunch of radials. > For 80 meters, I put a short "yard arm" at the top with a pulley and > hung a wire in parallel with the aluminum radiator. For only being > 45ft tall this antenna has worked surprisingly well. I've since > lengthened it to 56ft and added an additional parallel wire for 40 > meters. I use an Ameritron RCS-4 remote switch at the base to select > between 160 or 80/40 (the 80 and 40 meter vertical wires are tied > together). I use a 50 to 12.5 ohms Unun on the 160 side to raise the > feedpoint Z up to 50 ohms. With all these modifications done in haste > before various contests it aint pretty to look at, but it does seem to > hold its own against folks with shunt-fed towers and inverted-Ls (at least the ones who don't use overly active antenna tuners :-) ). > > Here are some pictures of it when I took a trip to one of the dry lake > beds north of here: > > http://www.dellroy.com/W4EF's-**Ham-Radio-Page/CQ160/2006.htm<http://w > ww.dellroy.com/W4EF's-Ham-Radio-Page/CQ160/2006.htm> > > 73, Mike W4EF............... > > > > > ______________________________**_________________ > Topband reflector - [email protected] > _______________________________________________ Topband reflector - [email protected] _______________________________________________ Topband reflector - [email protected]
