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BALUNS, UNUNS & Line Isolators

Where HAM Radio operators come to shop, http://www.PacketRadio.com
Our BALUNs use multiple composite cores selected to provide the widest bandwidth of any BALUN on today's market.  Out UNUNs are composed of similar, but not the same ferrite selections.  In either case, our multi-core antenna matching transformers (BALUNS) provide the best match across the HF and VHF spectrum.  Where impedance variations occur with an increase in operating frequency, our manifold ferrites exhibit a change that compliment this match. 
In addition to matching the feed-line cable to the antenna for maximum transfer of RF energy, the BUXCOMM MasterMatch BALUNS 
improve the radiation pattern for more predictable coverage. See with and without patterns above.

Antenna BALUNS, UNUNS, and Line Isolators

When you connect center fed antennas, like dipoles, Inverted Vee s, Loops, Yagis, Rhombics, etc, to coaxial cable,  care must be taken to insure that you don't end up with feed line radiation.  Not only can the loss in power be quite significant, but the radiation characteristics of the antenna system will also be seriously compromised. In lay terms, it won't be what you are expecting from the pattern of your antenna.

The feed-line, coax or twin lead is to be considered  part of the antenna.  RF currents can flow from the feed-line shield or wire feed-line into the utility power mains and into nearby t elevision and other communications cables.  Support masts and metal poles can cause a  variety of TVI and EMI problems that can be very difficult to trace.  Frequently these problems are due to the lack of antenna line-isolation or no BALUN to prevent this condition.  The solution is to use a BALUN at the feed-point of your antenna, or a Line-Isolator (B2KLISO) at the output of your transceiver or linear.  In other words, at the input to your coax feed-line to the antenna.

The Rule of Thumb:

1 to 1 BALUNs are used mostly with center-fed dipoles.
2 to 1 BALUNs are employed with high-frequency Quads and loop antennas (above 40 meters). 
4 to 1 BALUNs are commonly used with Windom's, Off-Center fed, and Sky-wire loops cut for 75/80 and 160 meters.
6 to 1 BALUNs are sometimes used with antennas that are fed with 300 ohm feed line. 
9 to 1 BALUNs are the BALUN of choice when feeding end-fed, long-wire antennas.
The 9:1 is also preferred when feeding a T2FD antenna that has a 450 ohm balanced terminating load at its center.

Here's the got'cha; When feeding mobile antennas that are end-fed, use coax cable, HOWEVER, the feed-point impedance of most (bottom) end-fed mobile antennas is somewhere between 15 and 35 ohms. To remedy this requirement, we have developed the B1K5022 UNUN. 

Where a VHF or UHF yagi is in use, improved transfer of energy is realized when using the B1VBALUN.  For practical purposes, the 12 to 1 and 16 to 1 BALUNs should be avoided where possible.  In rare cases. the 12 to 1 BALUN will be necessary when feeding an antenna with 600 ohm open-wire, transmission line.  A 16 to 1 BALUN is often used with Rhombic antennas that employ 800 ohm termination balancing network resistors.

BUXCOMM  is  BALUN  Headquarters.
BUXCOMM BALUNS are made in the Commonwealth of Virginia

We highly recommend using CoaxSeal, CS104 on all BALUN and UnUn
terminals and attachments.
Any BALUN installed out-of-doors is subject to harsh
weather, hard driving rain, and heavy winds. These conditions can allow
moisture to develop inside a BALUN when the connections are not sealed.

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