Do you have an old (or new) VHF/UHF TV yagi you'd like to put to a little more exciting use than TV reception? That antenna could be converted for scanner use with out too much trouble, and also be used to transmit 2 meter Amateur Radio. The un-modified antenna could be used without modification, but images and signal overload from TV broadcasters could be a problem. With the elements of the antenna unfolded to their normally extended positions, mark the longest elements (the hindmost elements) with a felt tip marker 21" from the boom, and the shortest elements (the foremost elements) at 16&1/2" from the boom. This should be done on both sides of the boom. After marking them, tie a string snugly from the mark on the rear boom to the mark on the fron boom as a cutting guide. Mark the remaining elements where the string touches them. Carefully cut off the excess lengths at the marks. The corner reflector (UHF) is modified as follows. Measure and cutoff all the corner reflector elements to 16" lengths (total length). Saw off the boom directly in front of the closest element to the corner reflector (ie. leave one of the elements that is attached directly to the boom). This element will be the one connected to the feed line. The conversion is now complete. Determine the new center of gravity and drill a couple of new mounting holes. Remember that the antenna will be mounted 90 degrees from its normally horizontal polarization, so that the elements are oriented vertically. If you can, feed the antenna with RG-8U. The antenna will need a 300 ohm feed, so a proper transformer will be required at the feed point. The antenna should be mounted on a 3' length of PVC pipe to prevent the mast from interacting with the elements. Although the antenna will exhibit gain and directivity at VHF and UHF, do not expect much in the 30-50 Mhz range. Good Luck!
Saturday, January 19, 2013
TV antenna as 2 Meter! (old text file)
This is an old newsgroup Text Info file! I just wanted to share what I can find from these lost archives Have fun!
at 7:40 AM