Great work Gary! This is probably a way that is much less expensive than the commercial version of doing this.
https://www.lbagroup.com/products/detunipole-detuning-skirt-kit Herb, KV4FZ On Tue, Mar 6, 2018 at 2:28 PM, kd9sv <[email protected]> wrote: > Herb, FYI...gary, kd9sv > > -----Original Message----- > From: kd9sv [mailto:[email protected]] > Sent: Tuesday, March 06, 2018 12:59 PM > To: 'David Olean' > Subject: RE: Topband: Excessive noise on beverages > > Dave, I have recently developed a simple "tower de-tuning system" that is > in > the "Beta Testing" phase. It will soon be available thru DXE as a system > to > de-tune a tower but I have no plans to use it on towers being used for > transmitting, however; I did design a system for doing that which only > requires adding one RJ1A or Kilovac HC1 type vacuum relay. I built one of > those for K3UL which he has not yet installed. I will send you the drawing > if I can find it on my computer. How are you feeding your tower? Gamma or > what? > > 73, de gary, kd9sv > > -----Original Message----- > From: Topband [mailto:[email protected]] On Behalf Of David > Olean > Sent: Tuesday, March 06, 2018 12:30 PM > To: Topband Reflector > Subject: Topband: Excessive noise on beverages > > I have been putzing around trying to improve my 160 meter setup, and > have run into a real problem. Most of the USA is covered by two > directions from here in Maine. SW and W. My problem is that I have an > excessively high noise level on both of the beverages that run in these > directions. In the last six months it has gotten worse, and so bad that > I cannot use either beverage. The wires terminate at the side of my > barn where I have ground rods and the RG-6 goes through PVC conduit up > to the shack on the second floor of the barn. During the day I see > noise levels at -133 or -132 on the two wires, but at night the noise > had climbed to levels around -100 or to -110 on a good night. I > suspected that I was getting noise coupled in from my vertical which is > rather close and on the other side of my barn all of 55 ft away. > > Yesterday, I modified the west beverage and shortened it so that it > terminated about 150 feet away from the barn and I ran new coax back > across the field. I kept the SW beverage as is to compare noise levels > at night. Lo and behold, but the noise went to -110 on the SW beverage, > but only about -120 dBm on the modified beverage. This is a 10 dB > improvement. Other directions at night run at about -130, so I am now > seeing a 10 dB extra hit in noise to the west. > > The vertical is a shunt fed Rohn 25 with a total height just over 90 ft > with top loading from a 5 element long boom 10 Meter yagi. I am not sure > if it is possible to simply un resonate this tower. Does anyone have > experience with simple ways to decouple a shunt fed tower from the rx > antennas? > > The extra 10 dB of noise that I get to the west and SW is mostly due to > the location of a town about 7 or 8 miles away in NH. It is ripe with > all sorts of power line noise. I still can't rule out re radiation from > the vertical though! I spent many years fighting with the electric > utility to quell the noise. I involved Riley Hollingsworth and later on, > Laura Smith, his replacement. The effort was futile and I lost heart as > the problem was just too big for one person to fight. I was hoping that > the noise would not affect 160 meters as it had messed up my VHF > exploits, and so far I only have this ten dB swath of noise that bothers > me in two directions. > > Any help with un resonating a shunt fed tower would be appreciated. > > Dave K1WHS > > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > > --- > This email has been checked for viruses by AVG. > http://www.avg.com > _________________ Topband Reflector Archives - http://www.contesting.com/_topband
