Radio Communications - Recent Questions, Troubleshooting & Support
Why did my mosfets blow in my galaxy dx 94hp. The swr meter on the radio was showing a good reading?
The integrated SWR meter is probably fairly accurate and decent gear should be able to tolerate a slightly high reflected wave without collapsing in sparks and smoke.
I am not an expert on such things but there are a few possible reasons why this disaster happened. It is possible the equipment wasn't designed very well or didn't use top quality components or was designed for a fairly short duty cycle or was intolerant to a high ambient temperature or a combination of all of these things. If the unit was used beyond the duty cycle and poorly positioned in a higher than recommended ambient temperature it wouldn't be surprising that one device might fail and the others would probably follow like falling dominoes.
A sustained overload is another possible reason for failure. If the devices were badly chosen so they had to perform close to their limitations they will be stressed and vulnerable to overload.
A power supply problem is also a possibility.
It is also worth noting some semiconductor devices or the entire circuit can suffer thermal runaway and self-destruct.
That is a lot to think about. Mostly domestic (non-professional) equipment is built down to a price and as a result has a low duty cycle and less tolerance to high ambient temperatures - the sort of temperatures found in a car during the summer or that can build when a unit is placed on an indoor shelf even with the recommended airspace...
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