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?
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.
Purpose. The CU-4-1500 is used as a 4:1 (200 ohm unbalanced load to 50 ohm unbalanced source) broadband transformer for 50 ohm coax cable rated at at 1500 PEP into 200 ohms unbalanced load from 1.8-61 MHz. Excellent for 31-33, 41 and 43 foot multi-band verticals and also slopers (51', 85' or 119" work great) made by S9, ZeroFive, MFJ and DX Engineering and Palomar Engineers vertical antennas
USE: The top connector is for the 200 ohm unbalanced output, and the side connector is for a ground rod, counterpoise or radial connection.The SO-239 input connector shield/ground is shared with the ground connector.
For best results use a feed line choke between the CU-4-1500 and the coax input to isolate the coax from becoming part of the antenna. Our Maxi-Choker (MC-1-3000) is an excellent companion for this unun.
This Unun is a very efficient match for many 43 and 31-33 foot multi-band verticals including the S9, ZeroFive, MFJ and DX Engineering vertical antennas.
The CU-4-1500 is also useful for end fed OCF antennas utilizing a 4:1 unun and a coax feed line choke to set the antenna length for the "short" side of the OCF.
CU-4-5000 is in a 4" x 4" x 2" NEMA enclosure and weighs 3 pounds and is specified for 1.8-31 MHz - rated at 5KW PEP
CU-4-5000HD is in a 4" x 4" x 4" NEMA enclosure, contains 50% more ferrite cores then the 5000 and weighs 4 pounds and is specified for 1.8-31 MHz - rated at 4KW continuous duty, 5K+ PEP. The HD version of this unun is CUSTOM MADE PER ORDER - PLEASE ALLOW 2 WEEKS FOR MANUFACTURING PRIOR TO SHIPMENT.
Likewise Termination Resistor values vary from 500-1250 ohms and we have a good selection shown HERE: