|The Pella 2-Meter repeater (WB0URW/R) is located on the Southeast corner of Pella, Iowa. The exact location of the antenna is Lat: 41 23.512 N / Lon: 92 52.540 W. The repeater sets at Lat: 41 23.509 N / Lon: 92 52.738 W. We set at about 850' above sea level.|
|Raacom Electronics has a business at the site but the towers are privately owned by Mike Vande Voort, who has permitted free homesteading for us. Our antenna is located on the left tower, just under the birdcage. These are 450' towers and the top of our antenna is located at 380'. Input frequency is 144.570 MHz and output is 145.170 MHz. This is an open repeater. Our intent is to create a wide coverage repeater with access to as many hams as possible. Output power is 75 watts.|
|This is just another view of the tower from the base of the tower. Our antenna is visible under the birdcage, to the right. Our antenna is an Andrew DB224-E (138-150 MHz) 5db/7db broadband antenna, mounted on a Andrew/Decibel DB5001 Side Mount Kit. Each of the elements is mounted 90 degrees from each other to make it omni- directional.|
|Our repeater is located inside this renovated chicken coop (remember, we live in Iowa). Open the front door and we have an insulated room with climate controll mounted on the back wall.|
|This shack has a lot of communications equipment inside of it and Raacom obviously likes Kenwood repeaters. They handle everything from commercial to private, paging, government, data, and internet.|
|We maintain all of our own equipment and have open access to the chicken coop. Here we have Jim Emmert, WB0URW, making adjustments to the repeater. Jim is the Trustee of the repeater.|
|We bought a Kenwood TKR-720K2 Wideband Repeater, 136-150 MHZ, Synthesized Single Channel with Built in 8 CTCSS/DCS Tones, 50 Watts @ 50% Duty Cycle, 15 Watts @ 100% Duty Cycle, Desktop Design (Rack Mount Kit Available), Large Heat Sink. 20/25/30 KHz Channel Spacing. Dimensions 4-3/4" x 13" x 15", 29 Pounds. The output is set to 15 watts which gives our repeater 100% duty cycle.
For our controller, we purchased the RC-1000 from Micro Computer Concepts. The RC-1000 is a controller for a receiver/transmitter operated in a repeater mode. The controller is all that is needed to control the repeater including a CW ID, control functions and the direct phone line connect autopatch. The RC-1000 contains the complete repeater and phone line interface requiring only the receiver audio and COS, the transmitter audio and PTT, and the phone line. If sub-audible tone access is desired for access a logic input for a externally supplied sub-audible tone decoder is provided.
We have had some problems in the past with losing the output from our final transistor and when that first happened, the tech told me that it got so hot that one of the solder tabs opened. I thought we solved the problem by reducing the power from 50 watts to 15 watts and then feed the 15 watts into our amplifier for about 75 watts out.
When the same problem occurred, a few years later (for some reason, it just wasn't adaquate having a quarter watt going through filters, tanks, amplifiers and 400' of coax), the tab was soldered with silver solder (higher melting point) and a muffin fan was attached to the heat sink in the back. The fan is on constantly and is fed from the +12 VDC that feeds the controller from the accessory plug in the back. The wires to the muffin fan have one wrap around a torroid core (just in case). The heat sink has an available hole in the back and we used this as an attachment point for the fan. The other side of the fan is glued on to the fins with industrial glue. This should be more than adequate to keep us in business at 100% duty cycle.
|If you can see through the web of cables, you will notice a DCI Digital Communications Inc. Two meter Bandpass filter, Model DCI-145-2H. Being in the same room with over a dozen other transmitters, and employing an open repeater, it was an appropriate decision to install this piece of equipment to protect us from RFI. We had a little trouble with something tripping our repeater but since we installed this filter, we run without any troubles at all.|
|The duplexer tanks are the Telewave VHR Dluplexer, 118-148Mhz. These give us about 75 db seperation.|
|An amplifier was attached to the transmitter. We chose the Crescend VVC100-25RF 25 in / 100 out. This amplifier is tuned to our output frequency at the factory. We feed 15 watts in, from the transmitter, and the output is 75 watts. This makes our repeater 100% duty cycle
The amplifier is powered with an Astron RM-50M power supply. 13.8 VDC, 50 Amp, and 60 LBS. Since this power supply can handle 50 amps continuous, and the amplifier only draws about 15 amps, our equipment should be able to run cool for years to come.
|On the back of the amplifier, torroid cores were attached to positive and negative leads, close to the amp (cheap RF insurance). They are held in place with electrical tape and then plastic ties are used on each end of the tape. I have never had one of these let go.|
|Lightning protection is accomplished with a PolyPhaser IS-50NX-C1 N Type 50-700 MHz Broadband dc Blocked Protector. The total grounding block is visible on the left and a close-up of our protector is on the right.|
|When we first moved into the chicken coop, there was a "boat anchor" setting in the corner. It was a Tripp-Lite BC-1200 Battery Backup System (UPS). From the looks of it, it has not been used for year(s). After some research, we found that it belonged to the local hospital and that they had a paging system from this location. This system has been moved to the hospital and the UPS abandonded. We immediately procured proper ownership, cleaned it up, and put it into service. It runs from a car battery on the inside and works perfectly.|
|The chicken coop also contains a UPS system. The panels on the left are the sensors, controllers, and breakers for the generator on the right. The generator is connected to a propane tank and we understand that it is enough to keeps things going for two weeks.|
|We figure that we have about a 50 mile radius, as pictured above. If a 203.5 tone is used, it connects to a fiber optic link (check our Fiber Optic Link project), which links several repeaters around the state. 911 can be accessed via phone patch and there is heavy use during weather nets.|