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week old rci 2970n2 started smoking at the back of it
- Thread starter boxcar112
- Start date
Whenever there are radios out there with mosfets in them, a shop 'peaks and tunes' it for max output, operator turns the output up all the way, and a less than perfect match on the antenna - the results are a recipe for failure.
These radios done by a particular CB shop has been famous for peaking them and sending them out - and they fail. A local bought one from that 'CB shop' in question, didn't even run it hard and it failed, and that very same shop made him pay the repair bill. Phony warranty! Ended up paying for the same radio twice. While mosfets might be half the problem, the radio 'tune-up' and the shop that did the work are really to blame - IMO.
There is a thread from a year ago or more that made all of this info known. RangerUSA recalled a bunch of these radios and set them up right when they first came out. Unfortunately, this same infamous CB shop is still ruining this radio. Beware . . .
These radios done by a particular CB shop has been famous for peaking them and sending them out - and they fail. A local bought one from that 'CB shop' in question, didn't even run it hard and it failed, and that very same shop made him pay the repair bill. Phony warranty! Ended up paying for the same radio twice. While mosfets might be half the problem, the radio 'tune-up' and the shop that did the work are really to blame - IMO.
There is a thread from a year ago or more that made all of this info known. RangerUSA recalled a bunch of these radios and set them up right when they first came out. Unfortunately, this same infamous CB shop is still ruining this radio. Beware . . .
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Yes you are correct.
It is the first thread in this section....sticky`ed to the top of the section.
73
Jeff
To summarize this thread in a nutshell:
I owned a Dodge Dart with a 225 Slant Six engine and the quick lube place cross threaded the drain plug so it had a large leak.
The engine seized from lack of lubrication so I will assume that all Chrysler Slant Six engines are not durable and long lasting!
I owned a Dodge Dart with a 225 Slant Six engine and the quick lube place cross threaded the drain plug so it had a large leak.
The engine seized from lack of lubrication so I will assume that all Chrysler Slant Six engines are not durable and long lasting!
Right.
I don't blame the use of mosfets in radios as much as I do the shop that attempts to turn these radios up so high that precipitates these failures. But some radio operators are also guilty for this failure too - trying to eek out the very last watt. The mosfet isn't the best device; but it has weaknesses that a bipolar transistor doesn't have. Mosfets are less tolerant of SWR than a bipolar transistor to begin with. It has been my experience that the mosfet also gets hotter than a bipolar transistor, and this contributes to this premature failure as well - IMO.
Everybody likes the mosfet because they can put out twice as much power as a bipolar transistor can. But then if one runs that way continuously; the mosfet fails. One can easily compromise here and just run it at ~75% of rated output (running the gate voltage just at the point that turns the device on), and then add a cooling fan to the heat sink.
Since Eleflow now makes the 2SC1969 bipolar transistor, one can only hope that radio mfrs get on board and start implementing these devices back into radio production. The FCC would be happy about the fact that radios are now putting out legal power levels, and radio operators will see less radio failures too . . .
:blink:
