Modified NISSEI RS-70 Digital SWR/Power Meter

[@Chris_Grossman]

Since it is by directional I would of thought you would connect the shields on both ends of the coax, not just one.

[@joesmith-je3tq]

Well, it is a transformer. Think of it this way. If you ground both ends, you now have a single turn output that is shorted. Basically, the transformer no longer will work. We want the braid to act as a shield.

[@technishn]

Did you check whether the Nissei has 1N4148 or low barrier schottky diodes? Changing them may improve the reverse power sensitivity.

[@joesmith-je3tq]

I didn't check. I thought about trying to align it by applying power to the input, with a known load then adjusting the reflected power until it reads the proper VSWR. The problem with this is I would need a stable load that could dissipate enough power. My small mismatched loads are not up to the task. Seeing the huge difference between the 100 ohm and 25 ohm mismatched loads, I doubt it would work out.

[@pjo7281]

I wonder if the RS-50 is as bad? I'm looking for a VHF/UHF meter for portable?

[@rocketman221projects]

The easiest way to remove hot glue from something is to put some isopropyl alcohol on it. That will make it quickly release from almost anything.

[@joesmith-je3tq]

My experience with that glue they use is that it doesn't adhere well to smooth surfaces. Pliers worked well and you could see, it left no residue behind.

[@johnshaw359]

Are there any unpopulated pads?

[@joesmith-je3tq]

If you watch the video, there were a few decent shots of the board. I didn't see any. I did trace out the schematic (shown in the video) which is pretty much what you would expect for a coupler.

[@wktodd]

I find it surprising that a company would market something so inaccurate. Is it just the result of reducing cost until they've broken the design?

[@joesmith-je3tq]

I'm sure cost is part of it. I would like to get my hands on the exact one that was sent to QST for review. I doubt they fudged their data, so we could compare the two and see what has changed.

[@LaserFur]

when I made a PCB based power meter I used finger like traces to make a static shield that did not block the magnetic part. So imagine single straight wires around the coax from both sides, but the wires do not touch. they just lay beside each other.

[@joesmith-je3tq]

This is similar to how the Para Dynamics coupler works. It's an air line made of a brass rod with I think five rods surrounding it for the various functions.

[@germanjohn5626]

You sure you connected the braid on the right side of the transformer?

[@joesmith-je3tq]

Why do you feel this matters?