Introduction: Frequency Measurement by Lecher Line
I measure the frequency of my UHF oscillator using a length of wire and a scale.
Step 1: Construction
A Lecher Line (look here for further info) was wired up using some bare wire taped to an empty tube some transistors came in. It can be a length of parallel wires stretched across the room, if this length is insufficient.
The loop at the end is for coupling to my oscillator. The current on the line is measured by placing a diode against the line and measuring the voltage across it.
The loop at the end is for coupling to my oscillator. The current on the line is measured by placing a diode against the line and measuring the voltage across it.
Step 2: The Measurement
The photo shows the setup. The wire loop at the end of the Lecher Line is placed near the oscillator. A diode has been taped near one conductor and the black and red wires lead to an analogue meter. A screwdriver is slid in contact between the two wires and the deflection on the meter is monitored.
The distance between two successive dips (or peaks) on the meter is taken to be half a wavelength.
In my case this distance was about 25 cm and so the wavelength is around 50 cm, a frequency of around 600 MHz.
The movie shows one such maximum deflection on the meter.
So, as I had promised, here is the frequency of my UHF oscillator.
The distance between two successive dips (or peaks) on the meter is taken to be half a wavelength.
In my case this distance was about 25 cm and so the wavelength is around 50 cm, a frequency of around 600 MHz.
The movie shows one such maximum deflection on the meter.
So, as I had promised, here is the frequency of my UHF oscillator.
