----- Original Message ----- From: "Brian Mattson" <[email protected]> To: "Guy Olinger K2AV" <[email protected]> Sent: Monday, January 30, 2012 9:22 PM Subject: Re: Topband: T vert feed
> Let me see if I have this right. With an unfortunate length of coax (half > wave or multiple thereof), the house ground rod appears as a 1.7 ohm > impedance at the base of the antenna feed. Why not avoid the tuned coax > complication and put a ground rod right at the vertical feed point. With a > 1/4 wave vertical at 36 ohms and a 1.7 ohm ground rod, efficiency is > better than 95%! I'm impressed....and who said a ground rod isn't much > good for verticals? Just think, you can pull up all those radials & sell > them for scrap copper... > > Brian K8BHZ > > ----- Original Message ----- > From: "Guy Olinger K2AV" <[email protected]> > To: "Roy" <[email protected]> > Cc: <[email protected]> > Sent: Monday, January 30, 2012 5:32 PM > Subject: Re: Topband: T vert feed > > >> Oh, yeah. It will. If you are unlucky and it is presenting a current >> node >> at the antenna connection. All the MORE likely if you have a really good >> ground at the house entry point. Get used to it. Each little wire >> running >> off from the center is a **DRIVEN** element in the system, and if the >> coax >> shield is not blocked, the coax shield is an element DRIVEN with power >> from >> the base of the antenna. >> >> It can be that low, it's insulated, it has a very large surface, and >> because there are miscellaneous distributed and specific terminations at >> the other end, you CAN very definitely have current nodes if it's driven >> with power at the antenna end. That is where you can get VERY low >> effective series resistances. Maybe you particularly will, maybe you >> won't, with your SPECIFIC piece of coax and routing, grounding, yada, >> yada. >> But the warning of the 50/50 possibility has to remain. I'm really quite >> sure some of you out there ARE lucky in this very miscellaneous regard. >> Carry on. Enjoy life. Kiss a pretty woman. Work rare DX. As for the >> REST of you..... >> >> The trick is to remember that without a block you are driving that shield >> with counterpoise power, the same as each one of the radials >> individually. >> >> 73, Guy. >> >> On Mon, Jan 30, 2012 at 1:53 PM, Roy <[email protected]> wrote: >> >>> This is the part I'm objecting to: >>> >>> "the coax will carry HALF >>> the counterpoise current and waste most of that power, besides being a >>> link...(etc.)" >>> >>> No, no, nertz. Where did that notion originate? >>> >>> Roy K6XK >>> >>> >>> >>> _______________________________________________ >>> UR RST IS ... ... ..9 QSB QSB - hw? BK >>> >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
