After many requests we have created a compact, special balun for Off Center Fed (OCF) , loop (Skyloop or Delta loop) , BBTD, T2FD, folded dipoles antennas. The CB-4-1-1500 is a CUBE(TM) 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 1000 watts CW (ICAS). 1.8Mhz – 61 MHz.
CB-4-1-1500 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.
5KW are in 4" x 4" x 4" enclosure. 1.5KW is 2 pounds, 5KW is 4 pounds.
For an 80 meter OCF antennas we recommend a (95 feet/79.5% and 40 feet/29.5% 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 at high power levels. Loop antennas should be cut for 1005/F(MHz) in total length, where F (MHz) is the lowest frequency to be used. For 3.5MHz this equates to 288 feet.
We highly recommend a feed line choke (MC-1-3000) or coax noise filter (CMNF-1500) at the radio end of the coax feed line to reduce common mode noise picked up by the coax braid.
CB-4-1-5000EB/TS are custom made to order - please allow 7-10 days ARO before ship.
Customer testimonial:
Callsign: NE5U Your CB-4-1500 +1:1 Choke made my homebrew, hail mary, 3 times folded 75m resonant attic dipole into a functional antenna from 6m to 160m. Most bands I can operate with no RFI. I've installed ferrites at all of the usual locations but still have some problem bands. Considering that the antenna is, at best, an NVIS antenna, I have made a lot of DX contacts (SSB, FT8 and other digital modes, and CW). Happy customer here. 73
We specify impedance ratios as an output to input ratio where the output (or load) is given first and the input is given second (e.g. 100:50 (2:1) would mean a 100 ohm output and a 50 ohm input; a 25:50 (1:2) would mean a 25 ohm load and a 50 ohm input). Most all products use a 50 ohm input unless otherwise specified.
We have products that are available as kits for the do-it-yourself (DIY) person or fully assembled and tested units for the “Plug & Play” crowd.
Our impedance transformers are available using two different topologies: Binocular cores or toroid cores with multiple turns for increased effectiveness and wide band frequency transformations. We utilize single and multiple core transformers using high order windings when needed to extend product performance.
We rate the power ratings as watts PEP (Peak Envelop Power) with standard duty cycles for various modes. To determine the PEP rating required for your needs, see: Choke & Transformer Power Ratings
This website page serves as a link page to the frequency ranges of our impedance transformers configured as either baluns or ununs. You can click on a picture to go to the specific page about the products described in the picture.