on a cobra 148 gtl Malaya 1997 can i replace the voltage regulator with a MJE3055T ??
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148 voltage reg
- Thread starter 1iwilly
- Start date
Then it can't - NPN doesn't work well (if at all) so it needs a PNP in there.
IT already uses a 2SA473 PNP - so the pinout is BCE - has to be an PNP
IT already uses a 2SA473 PNP - so the pinout is BCE - has to be an PNP
That radio should still have the original Uniden "emitter follower" modulator circuit with the NPN power transistor. MJE3055T is as legit as they come to replace the 2SC1419.
Our policy here any time that power transistor gets replaced is to also replace the 2SC945 transistor that drives it. Whatever kind of fault killed the big transistor can put a fatal surge into the transistor that drives it. Takes less time to replace a 2SC945 than to test it, so we just change it out.
Cheap insurance.
73
Our policy here any time that power transistor gets replaced is to also replace the 2SC945 transistor that drives it. Whatever kind of fault killed the big transistor can put a fatal surge into the transistor that drives it. Takes less time to replace a 2SC945 than to test it, so we just change it out.
Cheap insurance.
73
thanks after searching i order tip 41-C seems like a better choice from a few 148 old posted comments here
The issue here with the power transistor is the "DC beta", or current gain. The higher this is, the less load goes onto the tiny driver transistor. A lower-gain power transistor would make the 2SC1815 look a smarter choice like Andy said. And a high-gain power transistor will make a 2SC945 comfy. Any time you change one parameter in a circuit, unintended consequences occur. Just the same, the higher the gain of the modulator transistor in that radio the better, IMHO.
73
73
Yes you can or you can use an NTE153 or MJE2955T. I replace the 2SA1012's which is the AM regulator in the Uniden chassis that use the upd2824 pll chip as the original which is a 2SA1012 it's underrated so I use either a MJE2955T or the NTE153.
