CROSS NEEDLE SWR METER FROM TWO CHEAP MULTIMETER

Hi friends! An SWR meter is essential equipment for every radio amateur for antenna testing. Nowadays, many digital versions are available in the market, but analog versions are highly priced. In this experiment, I will demonstrate how to build a DIY cross-needle SWR (Standing Wave Ratio) power meter using two multimeter moving-coil mechanisms. Let’s get started!

This projects need two identical moving coil from any multimeters i took full deflection 100uA , if different current rated coil we need to add shunt resistor . bigger needle meter is best .we need tools ...sharp tweezer ,helping hand, screw drivers , spacer, red marking pen ,pencil , scale, gum . drill ,case (any )

I took my old watch case for a cross-needle analog SWR meter project. It can be drilled very easily. I also got another watch case with a transparent top cover, so it works well as the meter’s front cover.

Measure the meter coil mechanism and mark the angle at approximately 30° from the center line, as shown in the image. Mark the needle movement area. If the needle size is larger, adjust the position from the center line toward the moving coil screw hole.

Place the moving coil part on top of the front panel exact angle line mark screw hole and mechanism hole .

check needle smooth movement

Making a cross-needle meter for SWR: one meter stays straight, and the second one is flipped horizontally. The flipped moving-coil needle should be bent in the opposite direction, as seen in the photo. It is risky, but it can be done.

After flipping the needle, the opposite side should be painted red because the needle I received has no paint on that side. Height adjustment is required for the flipped mechanism so both needles can move to full deflection without touching each other. A spacer should be added for calibration and adjustment.

Now I am going to print the scale. You can download different types of scales from the internet, edit the size in Photoshop, and place it on the panel as seen in the image.

after fix two coils and scale cover meter as seen on photo now cross needle meter is ready for bridge coupler.

i attached short video of DIY CROSS NEEDLE SWR ANALOG METER 73 BYE