PCARA
POLK COUNTY AMATEUR RADIO ASSOCIATION
PCARA
Radio Enclosure - Repeater Link Project
mill_enclosure_vent
Photo: Greg N9CHA
July 14, 2011 - The plastic enclosure gets vent holes milled into the cover. Bruce N9BLU cut two sets of vents, one on the cover and the other on the bottom to incorporate a 5" fan and debris cover. The enclosure houses the radio link equipment which will need to survive an external mounting location in Taylors Falls.
 
UHF Yagi - Repeater Link Project
It's fun to build your own antennas! While there are several excellent commercial manufacturers making UHF beams on the market today, it's always fun to try and build one yourself. Greg N9CHA and Bruce N9BLU built a 6 element Yagi for use as a repeater link transmit antenna. The design is from Zack W1VT, published in the July/August 2001 QEX by the ARRL. Click HERE to download the plans and detailed material list.
N9BLU_CNC_Mill
Bruce N9BLU at the CNC Mill
Delrin_bushings
Delrin bushings
Bruce N9BLU used a computer controlled milling machine in his shop to precisely cut the Delrin bushings needed to mount the elements to the boom. By programming the spacer component into his CAD software, Bruce was able to transfer the data to the mill for cutting. The bushings were made slightly undersize for the elements, and slightly oversize for the boom in order to get a "press fit" to try and eliminate the star washers the design calls for. Once the bushings were cut on the mill, they were removed from the solid block using a band saw.
Trim_bushings
Trim bushings using lathe
Cutting_elements
Cutting the elements, measuring
The bushings needed to be trimmed using a lathe in order to get them to their final dimensions. The next process was to cut each of the 6 elements. The solid aluminum rod was cut to a rough dimension using the band saw, then trimmed on a mill to the exact lengths.
Boom
Boom, element holes drilled
Element
Element and Delrin bushings
The boom was then cut to length and each of the 6 element holes were drilled. Since this antenna is going to be mounted for vertical polarization, the boom to mast clamp holes have not net been drilled. Each of the 6 elements and their Delrin bushings were assembled to the boom.
 
 
 
Another VHF/UHF J-Pole Construction Project
This J-Pole project is very easy to build and a lot of fun.The antenna works very well and will handle a 35 watt mobile rig just fine. It is quite broad banded. I tested it on the VHF band from 145 to 148 MHz, as well as the UHF band from 440 to 450 MHz with an SWR less than 1.6:1. The construction plans are found in the March 2007 issue of QST. A copy of the plans can be downloaded by clicking on this link. Edison WB6IQN has done a lot of research into this construction project and published an excellent set of articles which have appeared in QST and others over the years. If you need supplies be sure to ask other club members. Note that the feed line can be RG-58 or RG-8 style coax. A short length of RG-174A is nice to reduce the potential tugging on the feed point, then transition to a more robust coax like LMR-400 or 9913.
J-Pole
March 2007 QST © ARRL
The version shown is made from 300 ohm twin lead often called ribbon wire. It was used for connecting television antennas in the days of VHF and UHF analog broadcasting. It's easy to find at hamfests if you don't happen to have any. There is a decoupling stub made from RG-174A coax. The antenna can be taped to a wooden dowel or a small diameter PVC pipe shown above. The completed antenna can be installed in a larger diameter PVC pipe to make it weather proof. The total cost of this antenna was $ZERO as I had everything laying around the shack.
The antenna was tested using a 40 watt mobile rig (VHF/UHF) and a Bird 43 watt meter. I suspended the antenna on a photographic light stand at about 7 feet. I measure forward power at 40 watts and the reflected power was at 2 watts. This calculates to 1.5 to 1. Very respectable. I was easily talking into our Balsam Lake repeater from Osceola. Simplex tests were conducted with Paul KB9PDX in St. Croix Falls and Chris KC9NVV in East Farmington.
VHF/UHF J-Pole Construction Project
Several PCARA members have built this project and have achieved excellent results. It uses common hardware store materials and is very cost effective.

Building antennas is fun, and when you get them to work, your signals are just that much better because of your hard work.

Using the plans by Andrew Griffith W4ULD, this antenna is cheap and easy to build. Materials include: copper water pipe and fittings, a bit of plastic pipe and some coax. In less than an afternoon, you too can build this excellent performing antenna.

Watch the construction video! You can view it here if you have broadband internet service. Or you can download a Windows Media version. Greg N9CHA shot and produced this video with the help of Joe AB9OU.

Have fun! This project uses tools you probably have in the workshop, plus a torch for soldering the copper pipe fittings.

KC9PJJ_J-Pole
Mark's KC9PJJ
VHF/UHF J-Pole

Use the play button above to watch the video, or right-click HERE to download a Windows Media version. Be sure to right-click, and select "save target as" so you can save it to your computer.

You can download the construction plans by clicking HERE. They appeared in the October 2000 edition of QST magazine.

N9XH - Polk County Amateur Radio Association - 1732 Forest Circle - Balsam Lake - WI - 54810 - Info@N9XH.org