AA1K

Towers
Home
W3PP towers down
Location
AA1K items For Sale
DX News
Mobile
Elecraft K3
160 TX array
160 BS/EF array
Towers
Beverages
The shack
Switching
QSL info
Packet
Sailing
2000 Jetta TDI
Contact
W3PP SK

Tower 2, 97 feet Rohn 45. Click for large image.
rohn45view.jpg
3-stack of 204BA, 3-el. HyGain 40m yagi, 5-el 10m yagi (40 and 10 now moved to other towers).

    Towers and antennas

There are currently six Rohn towers.

Tower 6 and Tower 1
3el40myagi0001.JPG
Left: 3-el Hy-Gain 40m yagi; Right: 5-el. 6m over 5-el 10m

Tower 3, 97 feet Rohn 25. Click for large image.
tower3lookingup.jpg
15-meter stack at 98/65 feet

Tower 1, 97 feet Rohn 25. Click for large image.
tower1lookingup.jpg
The 160-meter series-fed tower. 4-el 6-meter yagi on top.

Tower 1

Tower 1 is 97 feet of Rohn 25. This tower has a homebrew insulated base using three large ceramic insulators. They are about 8-inches diameter and a bit of overkill -- one would have done the job. To test their load I drove over an extra one that was cracked with my Jeep several times with no damage done.
 
This tower is series-fed as a vertical on 160 meters. For top loading, there is a 4-element 6-meter yagi, a recently added modified HyGain 105BA for 10 meters, a long 220-mHz yagi for the PacketCluster node backbone link, and a couple of phased 2-meter verticals for the PacketCluster user frequency. A small LC network at the base brings the tower into resonance around 1830 kHz.
 
A 1/4 wave wire for 40 meters is hung off the tower and works quite well as a backup to the 40m beam on another tower.
 
Large coils of coax or small hardline are wound on 6-inch PVC forms to serve as RF chokes on the feedlines and rotor cable going up the tower. These are placed right at the base. I could have eliminated these by shunt-feeding the tower but I wanted to be able to easily "float" the tower to enable tuning of the parasitic elements. Thanks to Tom, W8JI, for the RF choke idea.
 
Sloping T-shaped parasitic elements for 160 meters are hung off the top of the tower, supported by rope catenaries. These are spaced out 66 feet to the NE, SE, SW and NW, giving us a switchable 3-element parastic array in four directions. This project is still under construction -- so far I have the NE/SW elements and the SE element in place. For more info on this K3LR array see ON4UN's Low Band Antennas book.
 
An extra director (90 feet of Rohn 25, base loaded) toward Europe  gives us four elements in that direction.
 
There are 120 radials coming off the center driven element, and 120 radials coming off each of the parastic elements. These are 1/4 wave radials or as long as it takes to meet buss wires midway between elements.Radials are mostly No. 12 insulated THHN stranded wire obtained from a local scrap yard. Some are No. 19 enameled wire.
 
The tower is located in the middle of a small grove of about 20 loblolly pine trees that are about 70 feet tall. Guys are a mix of Phillystran and EHS steel with insulators.
 
Tower 2
 
Tower 2 is 97 feet of Rohn 45. This holds a stack of Hy-Gain 204BA 4-element 20-meter yagis at 33, 65 and 98 feet. Only the top one rotates (on a Tailtwister rotor); the lower two are fixed on Europe. A relay box at the base of the tower allows remote selection of any combination of the antennas.
 
Tower 3
 
Tower 3 is 97 feet of Rohn 25. This holds two Wilson 15-meter yagis, model 415-M. These are four elements on a 17-foot boom. They are placed at 98 feet and 65 feet,.
 
An inverted Vee for 160 meters hangs from 95 feet.
 
Tower 4
 
Tower 4 is Rohn 55, installed in the winter of 2004-2005, and has a HyGain Discoverer 7-3 three element yagi on top, with plans for a second one lower down to be a stack..
 
Tower 5
 
Tower 5 is Rohn 25, offering an additional director toward Europe.
.
Tower 6
 
Tower 6 is 64 feet of Rohn 25 sitting on insulators, serving as a driven element for an 80 meter parasitic array. Still under construction.
 
Other antennas
 
A rope catenary at 80 feet between Tower 1 and Tower 2 supports a 2-element delta loop parasitic array for 80 meters, switchable NE/SW.
 
Numerous Beverage antennas for receiving are described on another page.

Base of Tower 1. Click for larger image.
tower1base.jpg
RF chokes isolate feedlines going up the tower.

Click for larger image
Tower1Base_Closest.jpg
The ceramic base insulators on 160m tower.

Click for larger image
biginsulator2.jpg
Each insulator measures 7" diameter by 7.5 inches long; threaded metal flange is on each end.

Click for larger image
basecloseup3.jpg
The posts sticking up from lower plate end about 1" below top plate.

New tower serves as 2nd director of 160m vertical
160ArrayNE2.jpg
This is 2nd director toward Europe. 90 feet tall with small loading coil at base.

Click for larger image
sparkgap2.jpg
This is a spark gap for lightning protection. No sign it has ever been used.

Click for larger image
80mloops_.jpg
A pair of 80-meter delta loops are hung from a catenary between Towers 1 and 2. Apex about 70 feet.

Base of NW parasitic element, 160m array
160NWSwitch.jpg
The coil makes this element resonant about 1780 khz to serve as a reflector for SE.

Click on photo to enlarge
GuyPost.jpg
Elevated guy posts. For Rohn 25 Tower 1 in foreground, for Rohn 45 Tower 2 at rear.