A Field Strength meter is a handy gadget to have in the shack as it can indicate radiated power and can even help with tuning up the transmitter, especially a linear amp, which is tuned differently than other amp types.

They are simple and inexpensive to construct; many times the needed parts can be obtained from your “junkbox” or from local hams.  Several designs are presented below.

Perhaps the simplest meter is this ARRL design.

It is very sensitive; the antenna can be about 18″ of wire.  I use a collapsible antenna taken from a junked FM receiver/CD player.  The antenna length can be adjusted to suite your needs.

Obviously, if you are using a KW transmitter, you will probably need less antenna length to pick up the system and if your transmitter is a 5 watt job a little more antenna will be needed.

The 10K potentiometer will adjust the signal sent to the meter;  a 50, 100 or 200 microamp meter could be used.  A 50 uA meter will be the most sensitive but for the common 100 watt transmitter even the 200 uA meter will do well.

Googling “Field Strength Meter” will produce a multitude of designs.  Some of these will output the signal to your DVM meter, in case you cannot obtain a stand-alone meter.

Other designs will use a solid-state amplifier to enhance the received signal but this is not normally needed unless you use a meter that is not very sensitive, such as a 1 mA (1,000 uA) meter.   But that works quite well.  Use what you have.

Some designs will add a tank circuit to the antenna so that you can restrict the device to a certain frequency or band, but this is not normally needed for ordinary use.

Field Strength Meter Audio Output:  KM1NDY describes a simple circuit used to add audio to a FSM, in case it is necessary to have a method of hearing one’s CW keying.