12:1 Baluns/Ununs

Off Center Fed (OCF) 4:1 Balun and 1:1 Balun Combo, 1.8-61 MHz, 1.5/5KW PEP Option

SKU CB-4-1500OCF
$139.95
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Off Center Fed (OCF) 4:1 Balun and 1:1 Balun Combo, 1.8-61 MHz, 1.5/5KW PEP Option
Product Details
MPN: CB-4-1500OCF, CB-4-3000OCF, CB-4-5000OCF
Country/Region of Manufacture: USA
Input ohms/Output ohms: 50 in/200 out
Frequency Range < 2:1 SWR (MHz): 1.8-61 MHz for 1.5KW, 1.8-31 MHz for 3KW/5KW
PEP Power Rating (watts): 1.5KW/3KW/5KW
Enclosure Size: 4"x4"x 2"(1.5KW), 6"x 6" x 4"(3KW/5KW)
Weight (pounds): 3(1.4KW)/4(3KW)/5(5KW)

1500 Watt PEP rated 4:1 Current Balun + internal 1:1 Current Balun in one enclosure

After many requests we have created a compact, special balun for OCF and loop (Skyloop or Delta loop) antennas. The CB-4-1500OCF is a CUBE enclosure containing a multi-core, broadband 4:1 impedance transformer in series with a 1:1 current balun for extra common mode current choking to keep RF current off the outside of the coax braid and on the antenna where it belongs. The extra choking action also means that the coax feed line will not act as a radiator causing unnecessary RF interference (RFI). Rated for full 1500 watts PEP and 450 watts CW/FT8/RTTY (ICAS). 1.8Mhz – 61 MHz.

The CB-4-5000OCF (5KW PEP) have a frequency range of 1.8-31 MHz and does not cover 6 meters.

CB-4-1500OCF is housed in a 4” x 4” x 2” waterproof housing with SO-239 input and stainless steel eye bolts on the side for ease of connection to your wire antenna. Top eye bolt acts as an antenna hoist. Use this balun combination when you DO NOT have a vertical radiator.

5KW are in 6" x 6" x 4" enclosure. 1.5KW is 3 pounds, 5KW is 5 pounds. Note the 5KW models are made to order and shipment time is approximately 7-10 days after order date.

For a 135 foot 80 meter OCF, we recommend a 29.5%/79.5% offset for best all band results. If you use 66%/34% offset, do not use on 15 meters as the impedance mismatch may damage the balun under high power operations

12:1 Baluns are useful between 600-650 ohm balanced loads the impedance at the  end of the feed line is 600 ohms (1/2 wavelength feed line), or high impedance feeds for rhombic,  T2FD and traveling wave antennas.

12:1 Ununs are useful between coax and long wires with a load impedance near 600 ohms like a beverage antenna.  Shortwave listener antennas also can benefit with the 12:1 unun and it may provide a better match than 9:1 ununs – this means quieter noise levels and stronger signals so you can hear distance stations easier.