The RTV80

Want to cover all of 80 meters without a tuner?

The coax feed comes up between the two pieces of Plexiglas and is held in place on one side only with zip ties. The ¼ 20 SS bolts are inserted through the “bottom”, the 2 sheaves are dropped onto the bolts and the soldering is done before the “top” side is installed. The “rules” are the same as for any inverted V. Nothing we’ve done has changed the operational characteristics of a “standard V”, as far as we can tell. What did change was the ability to find the best apex angle as it is now just a matter of tuning to any given frequency and looking at the data, then raising or lowering the antenna and comparing to fine the best center height relative to end heights. Sam KC4TAQ - lowered the tower from 55 feet (and antenna) to around 35 feet but made no changes to the end heights and found it moved the residence frequency well down the band. All he had to do was take up on the winch (from in the shack) and it came back down to a 1 to 1 SWR. It does not appear that height is critical to this design. We are using a DC window motor direct driving a winch spool with Dacron rope to do the adjusting. Due to the distance from the top block to the winch, the Dacron level winds perfectly onto the spool. As an alternative, you could use a small boat trailer winch or you may even find a large bait casting reel in a flea market if you want to change frequencies at the base of the tower. In this case, some means of tracking the frequency change will be needed. One option would be colored heat shrink tubing placed at proper intervals along the Dacron rope to create a visual scale. When tuning from in the shack, we just use low power on the desired frequency and run the winch until the SWR falls to a minimum. Our objective was to design an antenna that would allow you to go to the local super center and find most of the parts you need. As you see in the documentation, the critical thing is to keep the returning wire as close as possible to the top wire. Stiffer wire may work harden quicker than the flexible stuff but you should get several years of service even with #16 or 14 stranded copper. The weight strips are to keep the blocks from flipping over. We didn’t want any extra metal in close proximity to the wire, hence the Plexiglas extension. Extra weight (lead sinkers) can be added to the bottom of the Plexiglas strips if needed. Theoretically, there should be no reason why you could not use this concept to go from 160 up to 40 meters or higher. It would require a multi-part pulley system at the turnaround block if you take up more than half of the wire in the system. A 40 meter trap may also allow for two bands. If you use a larger diameter wire from the feed point out to the trap then you should be able to cover the 40 meter band without a tuner. The counter weights need only keep a reasonable amount of tension on the wires. We used about 12” of 3” PCV pipe with a cap on the bottom and have it about half full of steel punch outs from one of our iron workers. Sand bags would work equally well. We would like to hear from anyone that decides to build this antenna.

Designed, built and tested by W4QJP & KC4TAQ.