RemoteBalun™

The RemoteBalun™ is an interface between balanced feeders and coaxial cable. A short length of low loss coaxial cable connects your tuner to RemoteBalun. The complication of routing balanced feeders into the radio room is totally eliminated.

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RemoteBalun™ 4:1 Current Balun $ 59.95
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Balun Type

Current

Ratio:

4:1

Operating Bandwidth

160-10 m

Power Loss, dB

<.8

Saturation Resistant

Excellent

Winding Z @ 14 MHz

> 1500 Ohms

Core Type

2 x Toroid

Power Rating @ 3.5 MHz

1.5 kW (power must be derated under some conditions)

Output Balance

Excellent

Load Variation Tolerance

Excellent

Input connector

SO-239

Output Connector

Wire

Size, case

3.5" x 3.5"


Applications

Ladder line-to-coax interface, external to the operating position. Use with a tuner.


It's Better

The RADIO WORKS brought you the RemoteBalun™ over 25 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!

The RemoteBalun™

The 'RemoteBalun' 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™, it's what an "external balun" should be.


More than you ever wanted to know about the RemoteBalun


Power Rating

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

Most modern tuner circuits are T-networks or similar circuit types which do not accommodate balanced transmission lines (feed lines). To provide a balanced output, a tuner 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 when using balanced feedlines. 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. At the very least, signal loss occurs and destructive heat is generated in the balun's cores and windings. The RemoteBalun™ is different. To further enhance output balance, a special circuit, we call it the 'X' configuration, uses two large ferrite cores in a 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 many factors. Among those factors are the impedance and reactance presented to the RemoteBalun, the operating frequency, and duty cycle. They are interrelated and build upon themselves. The 1500 watt power rating assumes normal duty cycle modes (CW and SSB) with the balun operating into a moderate impedance electrical environment. If you operate AM, RTTY or other modes where the transmitter produces high power for long periods of time (a high duty-cycle), you will probably destroy this balun or any other balun for that matter. It is possible to use ferrite baluns like the Remote Balun but you should derate the maximum power delivered to your tuner. 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. Tune up your transceiver normally. Adjust your tuner for a low SWR. Using the proper procedures for testing on the ham bands, go on the air with a CW signal and hold the key down for a minute or longer if your transceiver has a long, full power, key-down rating. Watch your SWR or reflected power meter. An upward drift in SWR indicates heating of the RemoteBalun's core. If there is a drift in reflected power, the balun's core is overheating. Hopefully, this is not the case. If there was no drift in reflective power, turn on your linear amplifier and adjust the transceiver's drive to produce a few hundred watts output from the linear. Again watch for a drift in reflected power. Continue increasing power output until you see the reflected power drift or you reach the maximum power you will use.

If you observe drift of the SWR or reflected power, overheating is occurring. Key up immediately.

There are two solutions to the core overheating problem. 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. Once reflected power drift occurs, it can increase rapidly, so shut down immediately. Reduce power and look for the power where the drift stops. This is the safe operating point.

Note that this test was done on key down CW. AM operation is different. The modulation peaks are four times the carrier power. Thus, you may be able to run 1500 watts on CW, but AM operation at 1500 watts carrier would produce 4000 watts on modulation peaks. Of course, that's well beyond the legal limit and it will certainly cook a ferrite balun not rated for that power and duty-cycle.

It's best to monitor your SWR for awhile when first using devices like the RemoteBalun. This will give you an opportunity to fine tune power levels based on your particular operating style.

Don't overlook the advantages of adjusting the length of the balanced feeders to bring down the impedance presented to the balun.

The Tuner* or Transmatch

* The term Tuner and Transmatch are used interchangeably these days. The "Transmatch was popular in the 1980's, but you'll find the word "tuner" used in most applications now.

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 designed specifically to be located a short distance from your tuner. 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, your SWR or reflected power meter 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.



An Alternative To Using Balanced Line

I have to add one thing at this point. We make the CAROLINA WINDOM® and the SuperLoop™. Both antennas are all band, coax fed antenna which avoid all the problems incurred with balanced feedlines. Plus, there is a performance advantage with either of these antennas compared to common balanced line fed antenna systems.

Now back to the RemoteBalun™.

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 tuner (the coax is user supplied). 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 can be custom-assembled for you. I suggest using coaxial cable lengths 16 feet or shorter. Longer cable lengths can be used, loss will be higher. Choose either SuperCable or ExtraFlex, the specs are the same.

Follow this link to custom jumpers.


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