(Gratefully copied from DJ0IP’s website)
In the past 30 years, the T-Network has established itself as the most popular matchbox design found in most ham shacks. It is a simple design that easily covers multiple bands, and it can be built using common, inexpensive components. The T-Network can easily match a broad range of impedances, making it the ideal matchbox for matching “whatever comes your way”. Unfortunately it is not always the most efficient matchbox.
The biggest problem with the T-Network is its internal loss – power lost inside the matchbox. Through improper tuning by the operator, the losses can be even higher – sometimes 50% or more.
Advantages of T-Network Matchboxes:
- Simple circuit covers a broad frequency range
- Able to easily match a very broad impedance range
- Component values and physical sizes are practical
- Component costs are reasonable
Disadvantage of T-Network Matchboxes:
- Difficult to tune / difficult to find the best setting
- Multiple settings “appear” to be optimum (show low SWR), but . . .
- . . . when tuned to these wrong settings, these matchboxes heat up, have unnecessary loss, and can even burn up.
- Very often these units are used at less than optimum efficiency settings !
- The operator needs to engage their brain when tuning!
This is probably the best matchbox technology for most hams who are just beginning and do not know yet what they will ultimately need. Selecting this matchbox technology is a low-risk choice, BUT IF YOU DON’T TUNE IT RIGHT, YOU MAY LOSE UP TO 50% OF YOU POWER INSIDE THE MATCHBOX. It is possible to get better solutions for some antenna applications, but at least this matchbox should always find a good match to the antenna. It certainly is a good starter matching unit!
IF YOU CHOOSE THIS MATCHBOX, YOU MUST LEARN HOW TO TUNE IT PROPERLY!