Application Notes for BUXCOMM BALUN`s
Definitions: BALUN = Asymmetrical to Symmetrical; UNUN = Asymmetrical to Asymmetrical
Current Baluns vs Voltage Baluns:
Current baluns, when referenced to ground or other metallic pseudo grounds allow its output terminal voltage, float to any level needed to provide equal currents within the antenna feedline or feedpoint conductor. Current baluns are designed to work with both balanced or unbalanced loads. Current baluns provide a common-mode isolation between the antenna elements. Transmission line transformers that are used as baluns, may actually be UNUNs that also perform well as broadband phase-invertors.
Current baluns isolate or add impedance to unwanted common-mode current paths, reducing common-mode currents. Current baluns are preferred because they perform better than voltage baluns in most antenna applications.
Voltage BALUNS attempt to force equal voltages to the output terminals. More often than not, the voltage BALUN will produce a phase shift between the output terminals and reference ground. If the impedance presented at each terminal is not exactly the same, feedline and load currents are not equal and/or opposite. The result is a feedline or coax shield that will re-radiate, and add to neighborhood TV interference. In addition, a voltage BALUN does not provide common-mode isolation (CMI).
As stated throughout our BALUN web pages, BUXCOMM manufactures and sell only "Current BALUNS."
Voltage BALUNS are only built when special ordered.
BUXCOMM model MM11
1:1 BALUN: 50 ohms to 50 ohms, or to feed dipoles and similar antennas with 40 to 75 ohm feed points. The 1:1 current BALUN is also used to feed the input to 450 ohm ladder-line of the G5RV.
BUXCOMM model MM21
1:2 BALUN: 50 to 100 ohms. This Balun is suitable for feeding Vertical Antennas, Quads, Loop antennas and Ladder Line antennas.
BUXCOMM model MM41
1:4 BALUN: 50 to 200 ohms. This Balun is suitable for the coupling 50 ohm coaxial cable to Windom’s, and off-center-fed antennas. Sometimes used with folded dipoles that are fed with 300 ohm twin lead.
BUXCOMM model MM51
1:5 BALUN: 50 to 250 ohms; Suitable for coupling 50 ohm coaxial cable to a Windom’s, when the Windom is more than 50 above ground. Other applications are trap type dipole antennas.
BUXCOMM model MM61
1:6 BALUN: 50 to 300 ohms. This BALUN is suitable for the adjustment to asymmetric fed dipoles such as Windom’s, G5RV, and zepp antennas. The BALUN is fed directly to the Windom and similar antennas. With double-zepp and G5RV antennas and use of asymmetrical feeder, the BALUN is positioned before entry of the cable into a building.
BUXCOMM model MM91
1:9 BALUN: 50 to 450 ohms for coupling Asymmetrical to Symmetrical feeders.
BUXCOMM model MM19LW
Long Wire 1:9 UNUN: Similar to above, except; asymmetrical to asymmetrical (unbalanced to unbalanced) Long wire antennas, Ground Plane`s, Verticals, and some types of "beverage" antennas.
BUXCOMM model MM101
1:10 BALUN The 10 to 1 BALUN may be used with T2FD and Folded dipoles where 500 ohm balanced termination resistorstm (BTRreg tm) are employed. The 10:1 BALUN is most often used with terminated folded dipoles having 500 ohm balancing termination resistor. and some types of "beverage" antennas,.. etc Other applications for a 10:1 BALUN are: **50/500 Ohms for end fed Beverage antenna, 1-30 MHz. Also used with 500 ohm terminated Rhombics, multi-layered, ALE and end-fire antennas. It is also used when feeding 450 & 500 ohm ladder-line,
BUXCOMM model MM121
1:12 BALUN The 12 to 1 BALUN most often used with T2FD and Folded dipoles where 600 ohm balanced termination resistorstm (BTRreg tm) are employed. Also used with 600 ohm terminated Rhombics, multi-layered, ALE and end-fire antennas. It is also used when feeding 600 ohm ladder-line, and some types of "beverage" antennas,.. etc The 12:1 (MM121 & BTR600) is used in 85% of all T2FD installations. In a few T2FD applications, a 16 to 1 (BUXCOMM MM161) BALUN is employed where an 800 ohm BTR is used.
BUXCOMM model MM161
1:16 BALUNS are used to feed T2FD folded dipoles, RHOMBICS and similar antennas which have an 800 termination resistor for balancing power distribution in the elements. A 16 to 1 BALUN is also used to feed some types of ALE and Beverage antennas.
BUXCOMM model MM5022:
This Mobile BALUN/UNUN is designed to put the RF power into your mobile antenna. More than 95% of all HF mobile antennas exhibit a low impedance input, between 16 and 32 ohms. The BUXCOMM model MM5022, HF mobile UNUN will match 50 ohm coax to mobile antennas having impedance(s) from 14 to 33 ohms.
BUXCOMM model MM5014
The BUXCOMM MM5014 matches 50 ohm coax cable to 12 > 16 ohms.
For use with direct connection to yagi beam, split feed, balanced mobile antennas, and NVIS High Angle Radiating antenna.
In some applications, the BUXCOMM MM5014 may be used when matching the feedpoint, impedance of a single loop,
multi-band quad or delta loop antenna.
BUXCOMM model HFVCMI
BUXCOMM High Frequency Vertical antenna Common Mode Isolator is designed to be installed at the base of your vertical antenna.
Contrary to popular belief that only dipoles need baluns. NOT SO, HF verticals fix'd or mobile (for mobile version, see model MM5022), can require baluns or common-mode isolators. The HFVCMI is a BUXCOMM product that fills this purpose to perfection. It's a current BALUN with specially fitted output terminals for ease of connecting to the vertical that does not use an SO239 input. The path can be charges moving through the feed-line and radiating conductors. In addition, if your match is near the feedline or coaxial cable impedance, you could realize gain from your vertical antenna. P=I2 R.
NOTE: When using an HF vertical, we recommend a minimum of 16 radials, bonded together and terminating at the base of the antenna... NOTE: I did not say connected TO the base... I say, terminated at the base. This is be the point where the coax shield or the ground post of the BUXCOMM HFVCMI is connected.
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