| Author |
Message |
    
Znut
| | Posted on Sunday, January 12, 2003 - 7:25 pm: | 
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What transistor(s) will best replace the MRF 453?
It's for a single pill amp.
Thanks,
Znut
Znut,
If you can't find the MRF453 you can use the NTE333 60W Out 4W In / Flange type.
Lon
Tech808 |
2600
| | Posted on Monday, January 13, 2003 - 12:13 am: |
|
These days, what's readily available seem to be MRF455, SD1446, 2SC2290 and 2SC2879. Of them all, the MRF 455 is probably the closest match. If this amplifier has one or more ceramic compression trimmer capacitors on the input and output, those will probably compensate for using a transistor that isn't precisely matched to the old circuit that matched the old transistor. Just peak them for best forward modulated power and a decent input SWR match.
If all the components are fixed types, you'll be stuck with whatever power it delivers. A bigger (higher-rated) transistor will often deliver LESS power than the old (smaller) transistor until the other parts in the circuit are changed to match the new, larger transistor.
One last thought. It's not a MRF453A, is it? The letter "A" at the end of the MRF part numbers indicates a threaded-stud mount that goes into a single hole in the heat sink. This package style became obsolete years ago. Everything made for the last 15 or more years has the more familiar "saddle" mount with two screw holes. Accomplishing THAT conversion is a whole 'nother can of worms.
73 |
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