Re: Topband: Feedpoint of short RX vertical
Jim, I made a braid breaker by using a binocular core 73-202 with 2 turns primairy and 2 turns on secondary . The term braid breaker comes from John s latest edition of low band DX ing I found that it is difficult to get signal levels identical on both elements when using it, so maybe better to use a good common mode choke at the feedpoint . Luc ON4IA On Sunday, June 8, 2014 5:24 AM, Jim Brown j...@audiosystemsgroup.com wrote: On 6/7/2014 12:13 PM, luc kerkhofs via Topband wrote: does it make sense to decouple the feedline at the feedpoint with a braid breaker ? It DOES make sense to decouple the feedline. I've never heard of a braid breaker. Under NO conditions should you open the shield == that prevents the shield from being a shield. The good ways to decouple the feedline are 1) a good transformer, a good common mode choke, and radials. See Chapter 8 of http://k9yc.com/RFI-Ham.pdf for winding guidelines for the choke. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Feedpoint of short RX vertical
On Sunday, June 8, 2014 5:24 AM, Jim Brown j...@audiosystemsgroup.com wrote: It DOES make sense to decouple the feedline. I've never heard of a braid breaker. Under NO conditions should you open the shield == that prevents the shield from being a shield. The good ways to decouple the feedline are 1) a good transformer, a good common mode choke, and radials. See Chapter 8 of http://k9yc.com/RFI-Ham.pdf for winding guidelines for the choke. 73, Jim K9YC Hello Jim The term braid Breaker has been in use over on this side of the pond for more years than I care to remember. It is just another term for a common mode choke and it doesn't actually break the braid. There is a Wiki entry for braid breaker and that contains a reference to The Radio amateur's guide to EMC by Robin Page-Jones (G3JWI), published by the Radio Society of Great Britain in 1992, so that gives you some idea of the age of the term. 73s Tracey G5VU _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Feedpoint of short RX vertical
Hello, trying to improve my RX setup, I have a question . When feeding short RX verticals with a coil and resistor in series, does it make sense to decouple the feedline at the feedpoint with a braid breaker ? 73 Luc ON4IA _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Feedpoint of short RX vertical
hi luc so you use a hi z rx arrya and you have matched the 7m long radials with a coil in resonaze? VY 73 frank -Ursprüngliche Mitteilung- Von: luc kerkhofs via Topband lt;topband@contesting.comgt; An: topband lt;topband@contesting.comgt; Verschickt: Sa, 7 Jun 2014 9:13 pm Betreff: Topband: Feedpoint of short RX vertical Hello, trying to improve my RX setup, I have a question . When feeding short RX verticals with a coil and resistor in series, does it make sense to decouple the feedline at the feedpoint with a braid breaker ? 73 Luc ON4IA _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Feedpoint of short RX vertical
When feeding short RX verticals with a coil and resistor in series, does it make sense to decouple the feedline at the feedpoint with a braid breaker ? There is no universal answer. The particular installation determines whether or not decoupling is necessary. Sometimes a ground rod alone is enough, and sometimes even several radials are not enough. Decoupling can help if: 1.) The ground system is marginal or poor. We do not want the coax feedline contributing signals or acting like part of the antenna. 2.) There is noise following the cable shields to the antenna I do not decouple some of mine because the feedlines are all buried a foot deep for 160-170 feet to the center, I have several reasonably long radials on each element, and the antenna is far from any noise. Some of mine I decouple, because they are near the house and the cables are not deep buried. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Feedpoint of short RX vertical
Tom, one of 2 elements is very close to the house ( 20 ft ) and coax is lying ON the ground, so I guess it is best to use a braid breaker ? In fact it is a test setup . I also have a receiver 500 meters inline with the antenna direction so I can check the F/B of my test setup Luc On , luc kerkhofs luckerkh...@yahoo.com wrote: Hello Frank, no it is 11 m high vertical without toploading feedpoint is matched with resistor and coil Luc On Saturday, June 7, 2014 10:09 PM, donov...@starpower.net donov...@starpower.net wrote: Hi Frank, My 8-circle array uses low impedance verticals, not high impedance verticals like the Hi-Z. My verticals use an inductor and resistor at the base of each vertical. In a Hi-Z array each vertical connects directly to the input of a high input impedance amplifier. The purpose of the radials in an array of short low impedance verticals is to provide a reasonably stable feed point impedance. Eight 23 meter radials provide adequately stable feed point impedance at my QTH. Radials are not needed at all in a Hi-Z array. 73 Frank W3LPL - Original Message - From: dl8yhrfrank--- via Topband topband@contesting.com To: topband@contesting.com Sent: Saturday, June 7, 2014 8:23:12 PM Subject: Re: Topband: Feedpoint of short RX vertical hi luc so you use a hi z rx arrya and you have matched the 7m long radials with a coil in resonaze? VY 73 frank -Ursprüngliche Mitteilung- Von: luc kerkhofs via Topband lt;topband@contesting.comgt; An: topband lt;topband@contesting.comgt; Verschickt: Sa, 7 Jun 2014 9:13 pm Betreff: Topband: Feedpoint of short RX vertical Hello, trying to improve my RX setup, I have a question . When feeding short RX verticals with a coil and resistor in series, does it make sense to decouple the feedline at the feedpoint with a braid breaker ? 73 Luc ON4IA _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Feedpoint of short RX vertical
On 6/7/2014 12:13 PM, luc kerkhofs via Topband wrote: does it make sense to decouple the feedline at the feedpoint with a braid breaker ? It DOES make sense to decouple the feedline. I've never heard of a braid breaker. Under NO conditions should you open the shield == that prevents the shield from being a shield. The good ways to decouple the feedline are 1) a good transformer, a good common mode choke, and radials. See Chapter 8 of http://k9yc.com/RFI-Ham.pdf for winding guidelines for the choke. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
