Hi, Bjorn Well, I can't argue with JC. With my first ever inverted L for 160, I had similar experiences as did his friend, AA7JV with; submerged radials. In my case, the inverted L was on the dam of a lake behind my house. Not salt water, of course, but the lake had been treated with some amount of copper sulfate to control vegetation growth. I cut perhaps 8 1/4 wave radials of bare 14 gauge stranded wire and weighted the ends with bricks. I then used my canoe to fan the radials over nearly 180 degrees of semi -circle and submerged them in the lake. Like AA7JV, I could see the driving point impedance drop and the VSWR bandwidth of the antenna system decrease as I added radials, reducing the ground losses. One of my earlier QSOs wasn with Jacky, 3B8CF, on Mauritius around my sunset, but I also worked VK3, VK6, JA etc. - all with about 400W. So, if you could move that antenna nearer the water's edge, and submerge that radial in salt water, I expect you might see some improvement. In any case, GL and have fun!!
73, Charlie, K4OTV -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of JC N4IS Sent: Wednesday, January 29, 2014 8:39 AM To: 'Björn SM0MDG'; [email protected] Subject: Re: Topband: Compromise vertical loading questions Hi Bjorn >>>>> How much I can improve by moving the coil up. What improvement should I expect if center loading at about 7 meter? How about moving the coil all the way up to the top loading spokes? Is it worth the effort? (the pole wont support much up there). .>>>>> Not much, changing the loading would increase the signal 5-10% , it is around 1 db, however if you can get close to salt water and get the radials wet your signal can increase 10db or more. AA7JV can comment better on that, but close to the water is not good, in the water is unbelievable better. George used get several wires tied with a stone and through it into the water, as you increase the number of the wires, you can see the impedance changing. You will may lose some of the radials and they need to be replaced. The radials could be very short and thin but they will work if in the water. I can hear you almost every day with the antenna you are using now. Regards JC N4IS _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
