Frequency measurement
Frequency can be measured with a frequency counter, calibrated receiver or suitable frequency meter. The instrument must cover the frequency being tested and have enough accuracy.
Simple frequency meters
A simple absorption wavemeter uses a tuned circuit. When tuned to the signal frequency, it absorbs energy and may cause a dip in transmitter output or a change in an indicator. It must be used carefully and with suitable test arrangements.
Digital frequency counter
A counter counts cycles during a known gate time. Longer gate times usually improve resolution. Input level, waveform, trigger settings and time-base accuracy affect the result.
Multimeter
A multimeter measures voltage, current and resistance. Select the correct function and range. Never measure resistance on a live circuit. Place current measurement in series with the circuit.
Oscilloscope
An oscilloscope displays voltage against time. It can reveal waveform shape, amplitude, frequency, distortion and noise. Probe rating and grounding must be considered.
RF power meter and SWR meter
An RF power meter measures transmitter output under stated conditions. An SWR meter compares forward and reflected power or voltage. Both must be rated for the operating frequency and power.
Signal generator and spectrum analyser
A signal generator supplies a known test signal. A spectrum analyser displays signal level against frequency. It can reveal harmonics, spurious signals, unwanted mixing products and interference.
Dummy load
A dummy load is a non-radiating or low-radiation load that absorbs RF power. It should match the system impedance and handle the transmitter power. It is used for safe bench tests where permitted.