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

Name: Off Center Fed (OCF) 4:1 Balun and Choke Combo, 1.8-61 MHz, 1.5/3/5KW PEP
Brand: Palomar Engineers
SKU: CB-4-1500OCF
Price: 139.95 USD
Availability: InStock

Store/Antenna Products/CUBE Impedance Transformers (<1:1, 1:1, >1:1)/Off Center Fed Dipole Transformers

SKU CB-4-1500OCF

$139.95

Bulk pricing available for quantities of 2 units or more

PEP Power Rating Select

1.5KW PEP Watts

5KW PEP watts (+$100.00)

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Quantity	Price per item	Discount
2 items	$127.95	9% off
10 items	$114.95	18% off
100 items	$108.95	22% off

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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

Store/Antenna Products/CUBE Impedance Transformers (<1:1, 1:1, >1:1)/Off Center Fed Dipole Transformers

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

When considering solutions for AM broadcast (550 Khz – 1.8 Mhz) you should consider Mix 77 ferrites available in a variety of shapes and sizes. Choose a size to give the maximum number of turns of the affected wire or cable.

AM broadcast transmits on a low frequency with large antennas. Consequently it takes a large antenna to receive the signals. Typical “antennas” are AC house wiring, phone lines, long satellite or cable TV cables, DSL/CAT5 lines running between rooms, etc. The device wires that connect to these “antennas” need to be choked with as many turns through the ferrite as possible. Some installation examples are shown below on this page.

For AC/ DC power cords and coax cables the F240-77 (2.4″ OD, 1.4″ ID) “Donut” toroid is the most popular. Also available are smaller toroid donuts and Mix 77 beads. Shown below is a graph with 8, 10, and 12 turns through the toroid – obviously more turns has higher choking impedance. Mix 77 toroid products are HERE and Mix 77 small beads (for small wires) are HERE

F240 77 Turns Comparison 1024x648 - AM Broadcast RFI Kits

F240-77 Turns Comparison from .1 – 8.1 Mhz

Shown below is a graph of frequency response verses choking magnitude for a F240-77 in the AM Broadcast band for a 12 turn coil around the toroid. (Same info as above but different frequency range).