THE TEST ATUs
UN-BALANCED ATUs
TEN-TEC MODEL 238-B "L-NETWORK" ATU
This ATU is rated 2kW, and will match just about anything.
More info and user manual:
The MFJ-901 is one of MFJ's very first ATU's. It is a simple L-Network that also included a built-in 4:1 Voltage Balun. DO NOT USE THIS BALUN.
Instead, use the external 1:1 Current Balun as I describe elsewhere in this section.
When testing the S-Match initially with the test antenna, using just an analyzer, I found the adjustment to be very difficult.
In addition, tuning was highly influenced by my hand touching the controls.
Considering that the S-Match is not available as a commercial ATU anywhere, and users must home-brew their own, I doubt there will be much serious demand for this tuner.
I DID NOT EVEN BOTHER TO TEST IT!
BALANCED ATUs
ANNEKE SYMMETRIKAL KOPPLER
This is the 200 Watt version of the Annecke Symmetrical Coupler, which is a modified version of the Johnson Viking (275 W.) matchbox.
Details: https://www.dj0ip.de/antenna-matchboxes/a-n-n-e-c-k-e/symmetrical-koppler/
The
MFJ-974-B is a
Balanced-T ATU, rated 150 Watts. It matches 12 to 2k Ohms.
I have owned a couple of these over the past 20 years and they matched many different antennas.
DECCA KW EZEE Match (Zed Match).
This was a very popular ATU in the U.K. I have owned a couple of these and used them to match all sorts of balanced antennas . . . before I was aware of the Annecke ATU's.
DJ0IP's Home-Brew S-Match
I built this version of the S-Match following a design shown on PA0FRI's web page.
Its "Variometer" inductor has 2 positions, "series" (high inductance used on 80m), and "parallel" (low inductance used on all other bands).
THE OVERALL WINNER:
The "ANNECKE SYMMETRIKAL KOPPLER"
This Link-Coupled Symmetrical Coupler is identical to the ANNECKE Symmetrical Coupler pictured at the top-right of this page . . . but about 4 or 5 times larger!
The unit tested is my Home-Brew Annecke Symmetrical Coupler, built with original Annecke components into a 19 inch Rack-Mount Chassis and mounted in a single-cabinet.
The first photo in the Gallery below shows the "original" commercial "Symmetrikal Koppler", followed by my my Coupler and photos of the insides of it:
Many Stateside Hams believe the old Johnson Viking Kilowatt Matchbox to be the best symmetrical matchbox ever built. Indeed it 'was' . . . until Alfred Annecke improved the design significantly!
The improved design added taps to the link coil on the TX side of the link, as well as a 3rd variable capacitor in series to the TX. This significantly improved the impedance range that the matchbox can match and often enabled a better match (lower SWR) than with the original J.V. Matchbox
I created an "UPGRADE" for the Johnson Viking Matchbox, bringing its performance on par with the ANNECKE, but I modified the circuit slightly. Whereas Alfred Annecke had the 3rd capacitor "floating", in series with the center wire of the coax to the TX, I moved this capacitor to the ground side of the link coil. This eliminated the need to "float" the capacitor, making mechanical construction easier.
You will find instructions for this upgrade on my website at the link below, as well as feedback from one of many users who have successfully implemented this upgrade.
BTW, many people performed 'half' of the upgrade, adding just the capacitor, but not the taps to the coil. This is much easier and improves the impedance matching quite a bit.