Antenna Tuners

Which Asymmetrical Matchbox should you use?

WARNING: THIS PAGE IS OPINIONATED!

I own and use three designs: L, T, and Differential-T.

So the question for me is not which one should you use,

but rather WHEN should you use each type?

ANSWER: Use each type where you can take advantages of its best strengths.

BEST STRENGTHS:

L-NETWORK: Highest Efficiency. I use the L-Network to match antennas which I only use on a couple of bands, and I always want to be sure that I have the highest effeciency. Specifically, I use it together with my low band openwire fed Vertical Dipole when I'm running high power. I use a TEN-TEC Model 238B. Normally I would not use an asymmetrical matchbox for this purpose, but I do not currently own a high power symmetrical matchbox.

Differential-T: Easy to Tune, Good Efficiency. I use this design to match antennas which are "supposed to be" 50 Ohms, but are not quite perfect. For instance almost any dipole, when trying to cover the full 80m band, or with a trap beam when operating towards the ends of the bands. Although this design has more loss than my Model 238 L-Network, the loses in the impedance range where I use it are tolerable, and this is easier to use than the Model 238.

T-Network: Wide Matching Range, Good Efficiency - though not always. I use this type of matchbox for portable use when I don't know what kind of antenna I will have to match at each QTH. I have a tiny MFJ matchbox that has served me well for over 25 years, and it gives me the widest flexibility. It is not the most efficient but it matches most anything I need when operating portable. I would NOT use a T-Network Matchbox for home use. [almost] NEVER!

NORMALLY, I DO NOT USE ASYMMETRICAL MATCHBOXES

FOR MATCHING ANTENNAS FED WITH OPENWIRE.

A SYMMETRICAL matchbox is the preferable solution here.

For most of my portable operations I use an openwire fed symmetrical antenna, so I almost always use my MFJ-974B symmetrical matchbox. As backup I have an old DECCA EZee Match. I've had it for over 30 years.
For home use, where I sometimes run an amplifier, I would need to use a high-power symmetrical matchbox, but I don't currently own one because they are very expensive and the really good ones are almost impossible to find on the used market.
- For cases like this, I use an L-Network (Ten-Tec Model 238B) with an external, HIGH POWER 1:1 current balun.
  - This matchbox was chosen after trying most everything else on the market including a Palstar AT-4K and other expensive matchboxes.
  - The reason I chose the Model 238B is for its broad matching range and excellent efficiency, even at impedance extremes.
  - The reason I use a 1:1 current balun and not a 4:1 balun is described HERE.