Hi Gary Would you send the info you have re. tower detuning that you designed for K3UR. (Am using 1/4 wl tower with elevated radials) Thank you Joel k4wm
Sent from my iPhone > On Mar 6, 2018, at 13:42, Herbert Schoenbohm <[email protected]> > wrote: > > 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 _________________ Topband Reflector Archives - http://www.contesting.com/_topband
