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.

1095388997 - Broad Band Terminated Dipoles (BBTD, T2FD)
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Bullet 50:600 (12:1) HF Balun, 1.8-61 MHz, 500/1500 Watts, T2FD, BBTD, ALE

Bullet-12B-500
$89.95
In stock
1
Product Details
MPN: Bullet-12B
Country/Region of Manufacture: USA
Type: NEW
Input ohms/Output ohms: 50 in, 600 out
Frequency Range < 2:1 SWR (MHz): 3-30
PEP Power Rating (watts): 500
Weight (pounds): 2
Antenna Compatability: T2FD, BBTD, ALE, Rhombic

The Bullet-12B-500 is a multi-core balun with a compact enclosure (looks like a bullet) enclosure that is lightweight and easy to transport for your fixed/portable ALE, T2FD or BBTD antenna systems. Also useful for low power rhombics and other wire antennas needing balanced 600 ohm output. Halyard hoist at top of balun for convenient attachment point. Input is via SO-239 coax connector and output with side eye bolt output.

This transformer requires a feed line choke to isolate the coax feed line from the antenna. A coax noise filter at the radio end of the coax is also recommended to reduce common mode noise current picked up by the coax braid.


NOTE: We rate our Bullet baluns (and ununs) VERY conservatively at 500/1500 watts PEP with a 50% duty cycle. Some manufacturers selling low cost baluns may use a 5% duty cycle for their PEP rating to make it appear you get a higher rated balun for a lower price, but you may in fact be getting be getting less. Their 1500 watts PEP really means 75 watts continuous or 150 watts at a 50% duty cycle compared to our 250 watts at 50% duty cycle. Our baluns typically cover a larger frequency range under 2:1 SWR which make your transceiver happy and probably will last longer with less electrical stress.

Remember we over engineer our products, to out perform our competition - just compare the weight of our baluns to theirs and you will know we put much more into our products so you don't have to worry about failure at a critical moment.

12:1 ununs show 9:1 unun picture but internal construction is set for 600 ohm output rather than 450 in 9:1

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