The Circuit
The most expensive part of the whole project is the meter movement. I got mine from Delia Electronics in Atlanta a few years back. Any value of meter from 50 uA(mu ampere) to 1 mA will work. The diodes Dl and D2 are general purpose germanium point contact diodes, 1 N34As or 1 N60s would be just fine, C 1 and C2 are 50-volt ceramic disc capacitors, I got mine in a grab bag at a hamfest Rl is l A watt and R2 is a 10k ohm pot from my junk box. I used a 2" x 3* x 1 1/2 inch plastic box from whereabouts unknown. The size of the box will be determined by the size of the meter that you use.
I mounted all the components on a small piece of perf board, then mounted the perf- board to the three solder lugs on the potentiometer R2. Next, mount the potentiometer in the hole cut for it in the box. Then connect the binding post to C 1 with a small length of hookup wire and connect the meter to the board. That's about all there is to it. Use your imagination to work out your own component mounting schemes. A word of caution: Don't forget to heat-sink the diodes' leads during soldering. Excessive heat can ruin them.
If you want to go to the extra trouble of making a printed circuit board, go ahead. Personally, I thought it was too much trouble for this particular project.
Testing the Meter
Testing is as simple as building the FSM. Just connect a short piece of stiff wire to the binding post and rotate the sensitivity control as you apply a signal to your antenna. It is a good idea to always start with the control all the way to the left to keep the needle from slamming into the stops, While the FSM only gives an indication of relative field strength, it will allow you to check for front-to-back ratio of beam antennas and to make a comparative analysis of different antennas. Get back into building and have fun
source : 73 Amateur Radio
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