(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!
COMMENTS:
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!