United We Stand  

Brainerd Area Amateur Radio Club  

Club Membership Meeting on Thursday, January 31, 2008
(l-r) Gary KØPOW and John WØJGY discuss mobile radios. 
(l-r) Jim WØJDS and Darrell ABØVP Hamming it up.
(l-r) Lyle KØLFV and Curt NØCRM at the BAARC Station enjoying coffee and cookies.
(l-r) Fritz WØKO and Jim WØYA talking about star gazing.  Jim mentioned that there will be an eclipse of the moon on February 20th starting at 7:43 PM and ending at 9:52 PM.  Watch the eastern sky if there are no clouds.  
(l-r) Bill Stroot, Lance Bragstad, and Luke Schramm of CTC (Consolidated Telephone Company) told the group about a new 700 MHz Wireless system on towers at Brainerd and Gull Lake.  Two 6 MHz-wide channels carry Internet and telephone to customers as far as 10 miles from the towers.  Details at http://www.ctctelcom.net

A Consolidated Telecommunications Company tower is shown on the left. Two of the 700 MHz antennas are seen near the top. This tower is 180 feet tall and is located in the Brainerd Industrial Park, just west of the Crow Wing County Fairgrounds. It is just 0.87 miles (1.4 KM) west of the KLIZ-AM 3-tower night-directional antenna system. KLIZ-AM operates on 1380 KHz, which makes the Consolidated tower almost exactly one-quarter wavelength in height. Needless to say, the new tower became a significant re-radiator of the KLIZ-AM signal.

The tower was successfully detuned by using a unipole system and the expertise of Radio Broadcast Technical Consultant Mark WØMH. Mark said, “We tried something different on this one. The three near-vertical 145-foot unipole wires are on the inside of the tower, rather than the outside. This was made possible because the tower is a self-supporting structure that is 22 feet across at the base. The wires are connected to the tower at the 140-foot level.

A unipole detuning box sits at the center of the inside of the tower. The vertical unipole wires turn horizontal at 8 feet above the ground and meet just above box. The box has a vacuum variable capacitor, which is adjusted to resonate the tower, via the unipole. The project when very smoothly and it worked as predicted to make the tower electrically invisible at 1380 KHz.

The management at Consolidated was easy to work with and approved the added expense even though they could have fought it in court. I give them high marks for being a top-quality local company.”

In similar projects, Mark detuned a water tower in Bemidji, MN, and a wind generator tower in Pipestone, MN. There are a few Hams who use unipole wires to feed towers. Mark uses a single-wire unipole for 80 meters on his 68-foot tower.


Steve Mott
KCØYTE
Vice-President
& Program
Chairman

 The BAARC February Membership Meeting will be Thursday, February 28th starting at & PM in Room 800 of the Brainerd High School South Campus building. The 8 PM speaker will be Carol Christenson, KCØMAK, from the Duluth office of the National Weather Service. Carol will tell the group how Ham Radio is used as a part of the Weather Spotter's Network. It is especially critical to note that weather service radars in Minneapolis, Duluth, and Fargo do not do a good job seeing weather in the Brainerd area. Those radars cannot see below 8000 feet in this area. The talk should be an interesting one. Everyone is invited and encouraged to attend.

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This page was last updated 02/03/2008  Ø