Broad Band Terminated Dipoles (BBTD, T2FD)

Broad Band Terminated Dipoles (BBTD), Tilted Terminated Fold Dipoles (T2FD) and Balanced Termination Folded Dipole BTFD) antennas can be designed to cover a large range of frequencies between 1.8 30 MHz.  Longer length antennas generally provide better low frequency efficiency but take up a larger footprint of land.   One BBTD that has worked well at the AK6R antenna farm is shown below.  Many other designs are available and can be found at www.HFLINK.COM as well as other internet sites.  Your mileage may vary using this antenna, but as a general coverage antenna for ham and shortwave broadcast, the simplicity can’t be beat even though an individual dipole on a specific band may out perform this broad band dipole.  Palomar Engineers has all the parts you need to build this antenna, so why not give it a try?

BBTD at AK6R 1024x726 - Broad Band Terminated Dipoles (BBTD, T2FD)

 

Depending on the source of the antenna design, different value baluns are specified.  Our Bullet(TM) baluns in ratios of 9:1, 12:1 and 16:1 are excellent for this type of antenna as they are broadband from 1.8-61 MHz and will take up to 500 watts PEP.

1653144023 - Broad Band Terminated Dipoles (BBTD, T2FD)
+3

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

CB-4-1500OCF
$139.95
In stock
1
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

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Likewise Termination Resistor values vary from 500-1250 ohms and we have a good selection shown HERE: