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Troubleshooting and install tools
5/26/2020

A year or so ago, NMEA began offering courses to technicians in the proper operation of basic tools and hardware used to install and troubleshoot marine electronics. Last month we discussed one of the topics—cable connectors and in March rolled out the first round of troubleshooting tools. This week is the second round of specialty tools that help you get a fix on things like proper VHF installations and voltage/current put out by a USB port. The article is excerpted from an article written for Marine Electronics Journal by instructor Johnny Lindstrom. Where the information gets a bit techy, we provide some background.

By Johnny Lindstrom

We broke training down into several general categories: DVM (digital volt meter), RF tools—watt and SWR meters, NMEA Data and Networking (PC tools, cable testing) and Miscellaneous. [The SWR meter or VSWR (voltage standing wave ratio) meter measures the standing wave ratio (SWR) in a transmission line. The meter indicates the degree of mismatch between a transmission line and its load (usually a radio antenna). Technicians use it to evaluate the effectiveness of impedance-matching efforts—Wikipedia.] In the process we demonstrated the numerous uses of the ubiquitous digital volt/ohm meter, illustrating how to measure volts, ohms and current.  

RF (radio frequency) tools

Following the training outline used in NMEA’s Marine Electronics Installer course for proper VHF installation testing, we were able to show how to test the VHF using a dummy load, and then again with the antenna in circuit.
 
First we measured the transmitted power into a dummy load using a standard Bird watt meter to confirm proper output power from the transmitter. Then we did the same test with the antenna in circuit.  During each test we used the DVM to measure the supplied power to the radio to confirm proper wire size and secure connections.

We also used a pretty cool tool that measures both forward and reflected power and displays them on an easy-to-read LCD screen digital VSWR meter. The Nissei RS-50M would be easy to carry in one’s tool bag and is a little more robust than a traditional Bird meter.
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