After rereading I caught a little boo boo. A single wire Beverage can still use a 9:1 transformer, its the termination resistor that must be reduced to compensate for ground resistance so you wind up with the 450-500 Ohms mentioned in the books..
Sorry for the confusion. Carl KM1H ----- Original Message ----- From: "ZR" <[email protected]> To: "Thomas" <[email protected]>; <[email protected]> Sent: Sunday, January 23, 2011 11:18 AM Subject: Re: Topband: Beverage ground rod substitute > The object is to establish a stable RF ground and not necessarily a very > low > ohmic one. Drive three 4-8' rods (use a rented rotary hammer drill) will > do > for starters with say 3 20-30' radials at each one. Radials can be under > the > Beverage 20' or so from the termination, double back on themselves or any > convenient path. I use cheap hamfest #20-22 insulated hookup wire just > laying on leaves and pine needles. > > My granite hilltop with only 4-24" of soil cover measures 200 Ohms with 3 > 4' rods driven at an angle and 3 20-30' radials each, at both ends. The > far > end of one also terminates at a point that I cant use any in-front radials > so one is at the termination, another to one side (a stone wall is at the > other side) and the last is back under the antenna about 10'. > > The transformer designs for a 2 wire reversible or single wire will have > to > be designed to subtract the RF ground loss. This is easiest with a > MFJ-259/269 and a single wire at first with a carbon pot termination. The > transmission line mode impedance doesnt change. So for my 4 700-900' > reversibles Im using 270 Ohms for the ground dependent windings and either > 175 or 93 Ohms for the transmission line calculations. Using the very high > 8500 Al BN73-202 binocular cores it is not possible usually to get a > precise match when only 4-6 turns are involved and contrary to the ON4UN > description you can wind at odd turns also; ie.a 5T winding can be center > tapped on turn # 2 1/2 which will be at the other end of the core....its > still balanced. Ive found F/B to exceed 20dB most of the time and be > better > or worse sometimes. I use an external switchable attenuator to calibrate > the > TS-950SD S meter so the results are accurate enough for this project. > > Carl > KM1H > > > > ----- Original Message ----- > From: "Thomas" <[email protected]> > To: <[email protected]> > Sent: Sunday, January 23, 2011 8:46 AM > Subject: Topband: Beverage ground rod substitute > > >> All of this talk about a short Beverage antenna has me thinking I just >> might be able to install one 250-280' E-W wire. One issue would be the >> ground rod. The earth here is Caliche which is quite similar in >> properties to concrete, so I can't drive a ground rod into it. I've >> thought about using short buried radials like I do with my K9AY, but the >> Beverage termination points will be in the extreme corners of my lot. >> >> Any ideas what could be substituted and might work as well as the simple >> ground rod earth? It is funny I find myself attempting to make the >> proverbial silk purse from the sow's ear! >> >> Tnx, Thomas - AC7A (Tucson) >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK > > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
