Fixing a NISSEI DG-503 / MFJ-849 Digital SWR Power Meter After an Odd Failure Mode.

[@dalerobinsuk]

My theory is the radio connected to it might have had a bad or missing connection to the negative on the power source (or higher resistance) And the return path was through the coax braid, which then would have gone through that negative wire which melted due to the excessive current draw back to the power source.

[@iPigee]

If you know how to calibrate the watt meter, I’d love to see. Mine feel off calibration.

[@fitcher-armchair-sleuth]

Those SO-239 Connectors are junk on just about all of them. I have an MFJ from GPS Central and on every connector the insulators floating and center pins are enlarged.

[@scanflight]

I had a problem with my Nissei. the SWR became bad on VHF on my installation After having measured all the cables, I connected a 50 ohm load resistor at the output of the Nissei and noted that the SWR was 2.0 from the input to the output (50 ohm load). A component (Condo?) could be defective in the VHF rear part or the coaxial socket(soldered metal box). I will return it for exchange under warranty. I report the problem here because it is the first time that a measuring instrument has caused this kind of SWR error in TX line. 73s

[@ruivalentect2ggx918]

You have a problem in the metal box (VHF/UHF) is not easy to fix...try to open it and check all components... 73 from CT2GGX