Hy Power Off Center Fed
The Hy Power Off Center Fed Antenna is a very efficient and effective multi band antenna. The Hy Power OCF80 80 meter version shows a positive SWR dip on the following bands: 6, 10, 12, 17, 20, 40 and 80 meters. For a coaxial fed, "One Antenna Do All" you can't beat the off center fed antenna. It is also a good antenna for shortwave listening. It has all Stainless steel hardware and uses #12 UV insulated wire. It is completely assembled and no trimming is required. The balun is included. The overall length is 135 feet and the power rating is 5000 watts. Here is some information on how it works:
If you take an 80 meter antenna and feed it in the middle, the impedance is around 72 ohms and an almost perfect match for 50 ohm coaxial cable. This same antenna is resonant on numerous other bands, such as 40, 20 and 10 meters. If you take this same antenna and use it on forty meters and keep the feed point in the center of the antenna, the feed point impedance will be around 3000 ohms. This is not a good match for coaxial cable. This antenna is a full wave antenna on forty meters but has to be fed at a different location if one wants to use 50 ohm coaxial cable. Move the feed point of this antenna so it is positioned one quarter wave length in from the end of the antenna. The feed point impedance of this antenna will again be about 72 ohms and is a good match for 50 ohm coaxial cable. If you use this antenna on 10 meters, again move the feed point of this antenna so it is one quarter wave in from the end. Again you will have a good match for 50 ohms coaxial cable and now have the makings of a long wire antenna with gain.
To make this same 80 meter dipole usable on numerous bands without moving the feed point for every band, you have to find a common point where numerous frequencies converge at a given impedance. By feeding this antenna one third of the way in from the one end, you will find this so called, "Sweet Spot". The only thing left to resolve is the high impedance of this antenna at that point. The impedance of the numerous bands, on this antenna, will range from as low as 150 ohms up to around 300 ohms at this feed point. By placing a 4:1 Guanella Current Balun (supplied) at this point you will have an almost perfect transformation of impedance so 50 ohm coaxial cable can be used. The end result would be an antenna that is usable on seven ham bands.
The total length is 135 feet. One leg of this antenna is 45 feet long and the other leg is 90 feet long. This will place the feed point of the antenna 45 feet in from one end. The OCF80 use the "GU4HF5KWA" Guanella 4 to 1 Current Balun (supplied) which is rated at 5000 watts. Please note that rope and leadin cable is not supplied. SO239 input.
The Hy Power OCF40 40 meter version is the same as the OCF80, but is only 66 feet long, the feed is 23 feet from the feed point and it only overs 6, 10, 20 and 40 meters.
The Hy Power OCF160 160 meter version covers 6, 10, 12, 17, 20, 40, 80 and 160 meters. This antenna is 268 feet long.
Model 
Type 
Bands 
Length 
Power 
Order # 
Your Price 
Order 
OCF160 
Off center fed 
160/80/40/20/17/12/10/6 Meters 
268 feet (82m) 
5000W 
#5679 
$214.95 

OCF 80 
Off center fed 
80/40/20/17/12/10/6 Meters 
135 feet (41m) 
5000W 
#1164 
$129.95 

OCF 40 
Off center fed 
40/20/10/6 Meters 
66 feet (20m) 
5000W 
#0946 
$114.95 

These antennas are now also available in QRP versions. They are rated at 250 watts. SO239 input. The OCF 40Q is shown above.
Model 
Type 
Bands 
Length 
Power 
Order # 
Your Price 
Order 
OCF 80Q 
Off center fed 
80/40/20/17/12/10/6 Meters 
135 feet (41m) 
250W 
#5473 
$119.95 

OCF 40Q 
Off center fed 
40/20/10/6 Meters 
66 feet (20m) 
250W 
#5474 
$ 94.95 

The QRP Micro version will fit in a large pocket. It is great for for travel and backpacking. Rated at 250 watts. It uses stealthy #18 stranded insulated wire and a BNC connection your coaxial cable. It features the GU4HF250M balun using the the same cores as the standard QRP OCF baluns, but in a smaller 3" x 2" x 1" enclosure. The OCF 40QM is 66 feet long with one leg at 23 feet and the other at 43 feet.
VIEW LARGER
Model 
Type 
Bands 
Length 
Power 
Order # 
Your Price 
Order 
OCF 40QM 
Off center fed 
40/20/10/6 Meters 
66 feet (20m) 
250W 
#6543 
$ 99.95 

