Here is the schematic diagram of this rf meter circuit.
Rf field strength meter circuit diagram.
The circuit is built around a ca3140 ic which is an operational amplifier.
How the circuit works.
Start your measurements by using low transmitter power and a near minimum sensitivity on the field strength meter.
The main stage acts as a crystal recipient.
The signal strength meter display uses analog meter 1 ma full scale.
Here is the schematic diagram of this rf strength meter circuit.
There is not much difference between the two circuits but only the 2n3906 pnp transistor used at the output of the figure 2 circuit to further increase the sensitivity.
Adjust c1 for peak reading.
This is an exceptionally simple rf field strength meter circuit.
The rf field strength meter circuit schematic.
It can be used from 2 meters to 160 meters.
The frequency is controlled by l and c.
The circuit use only one transistor mpsa18 as the active component.
The variable resistor on the field strength meter figure 3 the case circuit board and antennas for the field.
L1 480 khz to 2 4 mhz l2 2 4 mhz to 12 mhz l3 12 mhz to 40 mhz the antenna is made of 30 cm long metal rod.
It is important to use all leds from a same manufacturer same color and type because there is some difference between brightness and other.
Field strength meter this portable 90 db dynamic range rf field strength meter is simple to build.
For operating with 9 volts simply remove d5 and d6 diodes.
The circuit is using four leds which will show the low medium high and full signal strength indications.
Utilize a germanium locator diode like 1n34 yet aa119 is substantially more normal in europe a silicon one won t do.
Field strength meter circuit diagram.
Considering these factors a dual mosfet is used as an rf amplifier in this circuit.
The telescoping antenna may be adjusted to its shortest length when working at 2 meters to keep the needle on the scale.
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The field strength meter or rf detector circuit shown in figure 1 is a simple circuit using not more then 8 parts and a battery.
The circuit use only one transistor mpsa18 as the active component.
This circuit is another radio frequency rf field strength meter similar with our previous field strength meter circuit but with lower supply voltage only a single cell 1 5v battery.
The amplification can be adjusted by p1 and with s1 switch we can select three frequency ranges.
Also be used as wide band rf detector.
You re measuring field strength from a transmitting vhf antenna use a vhf an tenna on the field strength meter.
This rf field strength meter has no absolute scale if we don t calibrate the scale using a standard instrument but the important thing for this.
The signal strength meter display uses analog meter 1 ma full scale.
To use turn on transmitter and meter.
