Marius Lubbe ZS1ML

Greetings, radio hobbyists! This article is dedicated to the marvellous innovation in our hobby, the automatic remote tuner, specifically focusing on the MFJ-994BRT model manufactured by MFJ Enterprises, which has been making a significant impact within the amateur radio community.

Starting with the basics, an automatic remote tuner plays a crucial role in ensuring that your radio transmitter’s impedance aligns perfectly with that of your antenna. This is critical because impedance mismatch can lead to power loss, reflected power, and potential damage to your transmitter. The tuner automatically adjusts the settings to ensure optimal match between the transmitter and the antenna, thanks to internal capacitors and inductors. The device is termed ‘remote’ because it can be positioned away from the transmitter, at the antenna’s feed point, which can help to minimize transmission line losses and enhance the overall efficiency of your system.

Moving on to setting up the MFJ-994BRT. Here are the steps:


Aim to position the tuner as close to the antenna as feasible to minimize transmission line losses. Bear in mind the tuner needs protection from the elements; consider a weatherproof enclosure or a naturally sheltered spot.

CONNECT THE ANTENNA: Connect your antenna to the tuner’s output, typically using a coaxial cable. The type of connector you require will depend on your antenna’s specifications.

TRANSMITTER CONNECTION: Attach your transmitter to the tuner’s input, often with a coaxial cable.

POWER CONNECTION: Link the tuner to a power source. The MFJ-994BRT requires a 12-18V DC power source directly connected to the external box or a more elegant solution the MFJ-4117 Bias Tee DC Power Injector, (included) installed at your transmitter. More about that later.

TRIAL: With everything connected, conduct a test run. Begin with low power transmission and check the tuner’s ability to find a match. Once confirmed, you can gradually increase the power to your preferred operating level.

Please note, some users found the manual for the MFJ-994BRT slightly complex and less user-friendly. If you’re unfamiliar with these devices, don’t hesitate to seek guidance from a mentor or a member from your local club. That said between my “Elmer” Emil Böhmer ZS1XB and myself we did this install in a morning stint of about 3 hours and found it to be a simple and logical exercise.

In addition to the MFJ-994BRT, MFJ Enterprises also offers the MFJ-4117 Bias Tee DC Power Injector, a small device that boosts the functionality of the tuner by injecting DC power into the coaxial cable connecting your radio to the antenna tuner. It eliminates the need for separate power cables, simplifying your setup and enhancing its efficiency. Please note that this device is directly connected to the coax from the transmitter with the side marked “DC Block” on the BiasT pointing towards the radio. The other side then continues to the antenna or, amplifier, SWR/Power meter or whatever you have installed in-line. Add 12V DC power to the box in the shack and when ready make sure to set the “On” switch.

However, no product is perfect, and the MFJ-994BRT IntelliTuner™ has a few problems highlighted in online reviews:

While the unit is of extremely high quality, some reviewers are of the opinion that the tuner’s weatherproofing could be improved for use in severe weather conditions. Although it’s designed to be weather-resistant, you should still take sensible precautions when installing it outdoors. Nothing can be 100% weatherproof in all conditions. Installing at the base of an antenna is perfectly normal, but make sure it will have some ground clearance and not sit in a mud puddle. For my own peace of mind, I would also have some type of cover like a hollow, fake, fiberglass, rock for instance, over it.

Another reviewer got the install wrong because he did not read the manual and assumed he knew where and how to go about installing and operating the unit.

The MFJ-994BRT IntelliTuner™, along with the MFJ-4117 Bias Tee DC Power Injector, make an excellent choice for amateur radio enthusiasts seeking a reliable and versatile automatic antenna tuner. They offer a range of advanced features that ensure ease of use and superior performance across various antenna types.


The company also provides two other versions of this automatic antenna tuner, the MFJ-998BRT and the MFJ-993BRT. The MFJ-998BRT is a high-power model designed to handle up to 1.5 kW of power, suitable for individuals requiring high-power transceivers or amplifiers. Conversely, the MFJ-993BRT is a more affordable variant intended for individuals with lower power requirements, accommodating up to 300 watts of power.

To recap, the power limits for each model are as follows:

• MFJ-993BRT: Accommodates up to 300 watts of power.

• MFJ-994BRT: Can handle up to 600 watts of power. = The model I have.

• MFJ-998BRT: Can manage up to 1.5 kW of power.

No matter which model you opt for, rest assured you are choosing a high-quality automatic antenna tuner that provides superior performance and is user-friendly.

On a personal note, the MFJ-994BRT has significantly improved my radio communication setup. I’ve noticed an uptick in performance from my 80M full wave delta loop antenna. From the moment I started using the tuner I started picking up more traffic and noticeably clearer signals and receiving better reports on my signal from my many new QSO’s. I ascribe it to the fact that there are so few losses with the tuner extremely near the antenna feed point, in contrast with a tuner in your shack that also have to contend with your length of coax all the way out to the antenna feed point. Frankly, it’s been an absolute joy to witness the difference this tuner has made to my setup.

I’ve found the MFJ-994BRT to be a fantastic addition to my setup, and I recommend it for anyone serious about their radio operations.

Well done, MFJ!

Look out for a long-term progress report in a year or two.



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