Current

4:1

160-10 m

<.8

Excellent

» 40 Ohms

> 1500 Ohms

2 x Toroid

1.5 KW (power must be derated under some conditions)

Excellent

Excellent

SO-239

Wire

3.5" x 3.5"

The RADIO WORKS brought you the RemoteBalun several years ago, and it was an immediate success. At the time there was no other balun on the market designed specifically for this purpose. In fact, back then, 'Current Baluns' were nearly unknown in Amateur Radio circles. As is always the case, success breeds copies, and soon there were lots of copies of the RemoteBalun (at least in name, but little more).

The original RemoteBalun was good, but we have been engineering baluns for a long time at the RADIO WORKS and if you do your homework, you can always come up with improvements .... and that is just what we've done!

We increased the RemoteBalun's winding inductance without restricting bandwidth. We improved the output balance and lowered losses. We added 160 meters and increased the power rating safety factor. We increased the high SWR load tolerance. We made a better RemoteBalun.

The 'RemoteBalun IV' is based on the B4-2KX, network compensated, Current Balun technology. Special winding techniques insure wide operating bandwidth and high power handling. Massive ferrite cores keep everything under control and the specifications on target. Try the RemoteBalun 4, it's what an "external balun" should be.

Power Rating

The power rating of the remote balun is based on normal SSB and CW duty-cycles and moderate impedance levels.

Most modern transmatch circuits are T-networks or similar circuit types which do not accommodate balanced transmission lines (feed lines). To provide a balanced output, a transmatch of this type will have a built-in balun. Unfortunately, the balun used is almost always a voltage-type design. Voltage baluns are inappropriate in this application. Voltage-baluns do not work well when their loads are mismatched. This is almost always the case in this application. Worse, high power, especially in combination with reactive loads can cause most voltage baluns to saturate. This can lead to TVI and other RF interference. To further enhance output balance, a special circuit, we call it the 'X' configuration, uses a twin core, balanced design that insures a balanced output under a wide range of conditions.

The RemoteBalun's power rating is conservatively rated at 1500 watts. It is not possible to put a specific value on this specification because the power rating depends on so many factors. The impedance and reactance presented to the RemoteBalun, the operating frequency, and duty cycle are interrelated factors that must be taken into account. The 1500 watt power rating assumes normal duty cycle modes (CW and SSB) with the balun operating into a moderate electrical environment. If you operate RTTY or other modes where the transmitter produces high power for long periods of time, you should derate the maximum power delivered to your transmatch. The same thing holds true for very high or very low impedances.

Checking the power limit

It is good practice to insure that your operating conditions are not causing overheating of the RemoteBalun. Simply check the balun's operating temperature on each of the bands you operate. The procedure is simple. Monitor your SWR or reflected power meter after you have properly adjusted your transmatch. an upward drift in SWR indicates heating of the RemoteBalun's core. If overheating occurs, there are two solutions. One is to reduce the level of mismatch and the second is to reduce power. An often effective, simple solution is to change the length of the balanced transmission line. A small change in the length of the balanced transmission line can have a dramatic effect on the impedance and reactance presented to the RemoteBalun. In difficult cases, the addition or deletion of 1/4 wavelength of transmission (on the band causing the greatest overheating) will usually do the job. As a last resort it may be necessary to reduce power, but in most cases, adjusting the length of the balanced feeders will eliminate the problem.

The Transmatch

Most modern transmatch circuits are T-networks or something similar. This type circuit does not accommodate balanced feedlines. Most transmatches use a built-in balun to convert the transmatch's unbalanced output to a balanced output. Unfortunately, the balun used is almost always a toroidal voltage-type design. They are not appropriate in this application. Toroidal baluns do not handle high impedances or high power very well. They can saturate and distort your signal which can lead to TVI and other RF interference. In contrast, The RADIO WORKS' RemoteBalun are Current-type baluns. Cores are designed to resist saturation. The twin core design is inherently balanced. Excellent balance is necessary to reduce radiation from the open-wire or ladder line.

Tuned Feeders

A single antenna that can perform well on any frequency of choice is certainly attractive. Full-size dipoles and closed loops, feed with balanced feeders are efficient, all band radiators. The one drawback is the inconvenience of finding a suitable way to get the balanced feeders to the tuner at the operating position. The RemoteBalun comes to the rescue. The RemoteBalun is first balun designed specifically to be located a short distance from your transmatch. RemoteBalun design is critical. It must allow for the extremes that exist with an antenna fed with balanced feeders. The RemoteBalun must handle high power at moderately high impedance loads without adverse affects. On some bands the antenna's feedpoint impedance, combined with the effects of the balanced transmission line, will present a high impedance to the RemoteBalun. Under these condition, the SWR indicator will drift upward, indicating the balun's core is heating. Power must be reduced. The instruction manual covers this subject in detail and offers suggestions for remedies.

The Secret

The secret of the 'RemoteBalun' system is the combination of a properly designed balun and a very low loss coax interconnecting the balun and the transmatch. You could use conventional coax, RG-213, for example, but the losses will be higher than with our low-loss interconnecting cables made using premium quality SuperCable or ExtraFlex

Preassembled Cables

Low loss cables in any length are available. I suggest using coaxial cable lengths 16 feet or shorter. Choose either SuperCable or ExtraFlex, the specs are the same.