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Wednesday, March 01, 2006
10 Meter Beacon Project
A few years ago a friend of mine made a 10 meter beacon and put it up on the air for a few months. Intrigued by this I decided that this would be something i would like to attempt as well.
My first 10 meter transmitter was home built and based upon the popular 'OXO' transmitter designed by GM3OXX and is pictured below. It put out roughly 800mw to 1 watt. Installing the trimmer cap allowed me a little more latitude in frequency selection. The crystal is 28.258 mhz and with the trimmer I could go down to 28.250mhz. The final PA had a tendency to get quite warm after continuous operation so that transmitter is currently retired til I beef up the final from a 2N3866 to a 2N3553. It is fed into a 10 pole low pass filter and a 10 volt power supply and keyed with a PK-4 keyer.
Needing and wanting something a little more industrial I found information on converting an old 23 channeled crystal controlled CB into a CW beacon transmitter. I will not rehash the details of the conversion here as it is well covered by it's author Bill, WJ5O. My setup follows his conversion instructions and Bill kindly offered much advice and assistance via e-mail for which I am very grateful. My beacon is transmitting on a frequency of 28255.5 24/7 and I hope to move it to a more permanent location soon.
The rig is pictured below. Nothing fancy but it works. The PK-4 keyer sits on top which is powered from a voltage tap inside the rig. It is all powered by a small 3 amp Tripp-Lite power supply. I am considering adding a UPS computer battery backup to run it. If you have any questions about the setup feel free to ask.
UPDATE!!!: Installation is complete! A friend who lives nearby has offered me use of his farm for the transmitter installation. It's not your typical farm. He raises Cadillacs! Well, collects them any-ways, sells some for parts, sells some as complete cars. He has over 50 vintage Caddys from the 40's, 50's and 60's. Any-way, one of the old chicken coops now serves as storage and a shop. The transmitter is installed in the shop. I have upgraded from a 1/4 wave vertical to a Cushcraft Ringo AR-10 5/8 wave vertical which is mounted 12 feet above ground on the NW corner of the shop/old chicken coop. A very satisfactory arrangement indeed. I can monitor the beacon from my QTH quite handily! Here's a pic of the antenna installation:
