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How to Read Antenna Tuners

An antenna tuner is a device radio amateurs use to match the impedance of an antenna to that of a transmitter. They are most common on the high frequency bands where antennas are physically large and may be used on several different bands. Also known as a transmatch, the most commonly encountered antenna tuner design consists of a variable capacitor on the input side, another variable capacitor on the antenna side and a variable inductor between the two capacitors. Antenna tuners also include a forward and reverse power meter, which the operator reads when adjusting the tuner.

Things You'll Need

Transceiver
Morse key

Instructions

- 1
  Connect the antenna to the tuner. Set the tuner input and output capacitor controls at their midpoints.
- 2
  Turn on the transceiver and set it on a clear frequency near the desired operating frequency. Step through all of the inductor settings on the antenna tuner until you find the setting that gives the maximum received noise in the receiver.
- 3
  Switch the meter on the tuner to "Reverse" or "Reflected Power." Turn the transmitter output power to its lowest setting. Set the mode switch on the transceiver to the "CW" position and plug in the key.
- 4
  Close the key to transmit, while observing the meter on the tuner. Adjust the input and output capacitor controls for minimum deflection of the meter. The needle should fall to nearly zero; if it doesn't, release the key and change the inductor setting up or down and try again. Continue until you achieve near-zero deflection of the meter.
- 5
  Advance the power control while continuing to transmit. Fine-tune the input and output capacitor controls for minimum meter deflection, then release the key.
- 6
  Switch the meter to "Forward Power." Key the transmitter and read the output power directly from the meter.

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