Topband: FW: Excessive noise on beverages

[Joel]

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 <herbert.schoenbohm at gmail.com> 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 <kd9sv at comcast.net> wrote:
>> 
>> Herb, FYI...gary, kd9sv
>> 
>> -----Original Message-----
>> From: kd9sv [mailto:kd9sv at comcast.net]
>> 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:topband-bounces at contesting.com] 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
>> 
>> 
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