The Rybakov 806 Multiband Antenna is a little different to other antennas I have made in that it is designed to not be resonant on any of the amateur bands. What makes it special is that because it is a non-resonant antenna it tunes up equally as well (or as badly) on the WARC bands as on 7/14 and 28Mhz with only 7.6m of wire. Some have found that with a longer wire, in the region of 8.6 to 21m that they can use the antenna on 3.5mHz.
http://www.iv3sbe.webfundis.net/html/Rybakov806.htm
I became interested in this antenna when Peter ON3WAB mentioned that he and Lieven ON4CVL were using one, made by Lieven, on a SOTA activation from Hotondberg ON-022 using an Icom 703 and 10w and putting out a fabulous signal. It seemed ideal for those summits where you cannot get a dipole up and a number of constructors have claimed it out performs trapped verticals. Pictures from the ON activation - http://www.flickr.com/photos/9924647@N08/
The only thing I did not have to make one of these was the T-200-2 Toroid which I found on eBay for under £4 from Spratreader ([email protected]) who is actually Les Jackson G4HZJ a member of West Manchester Radio Club.
I wish it was on4wab Steve, but it is "only" on3wab ( foundation ) so 10w.
ReplyDelete73
Peter
Updated sorry it took so long
ReplyDeleteOnly one thing about the UNUN isn't cllear... Which wire should be used...
ReplyDelete1,75mm² or just an 0,75mm²
1,75mm² seems not to be available, but on an another page IV3SBE states that he used 0,75mm² so what should be used...???
I don't believe there is any difference so long as the windings are correct. I used 30amp (50 amp surge) twin figure 8 red/black power the same as the 12v power cable to my Icom IC706 mkIIg and Yaesu FT-857D rigs as I had a full 100m reel of the stuff. I suspect what I used is 2 or 2.5mm² but I know people who have made them using much thinner figure 8 speaker cable. 0.75mm² seems quite thin but should be okay. I use 0.75mm² hook up wire for making dipoles and have never had an issue running 100 watts HF through them. I suggest you make it and try it. You can always rewind with heavier cables if you think it is causing losses or getting too warm in use.
ReplyDeleteGood luck 73 Steve GW7AAV
Very intriguing antenna design. Currently assembling the parts to build one, but have one question.
ReplyDeleteHow critical is the length of the coax attached to the UNUN?
73,
Ron - KJ5XX
> How critical is the length of the coax attached to the UNUN?
ReplyDeleteAs far as I am aware it is not very critical. I have only used random lengths that I had to hand (25-30 feet). The only danger is if the coax is a full wave length or multiple of on a band you wish to operate on. In which case the swr might look okay but the coax can act like a dummy load, but that is the same for any antenna system.
Have fun. 73 Steve GW7AAV
A practical antenna for everyday usage!
ReplyDeleteFor the last 6 months I have used a 25' vertical radiator and 21' c/p wire with either the 4:1 unun from the above illustration or the dual 9:1 & 4:1 unun from ON6MU . The reason for the 9:1 was the inability to load 18mhz less than 1.8:1. I like things FLAT!
Most of the time the antenna is on the roof about 15ft off the ground, but I have had the antenna mounted on the ground for field day preping. Similar tuning and qso's.
Results? China to Cape Verda with 50 watts on 10-14-18 mhz.
73'S
Bill N7MOB Washington (the state)