| Author |
Message |
    
Moderator558
| | Posted on Thursday, January 23, 2003 - 12:26 pm: | 
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I am saving my pennies for a amp and the one i looked at has 8 MRF-150 MOS FETs
What are MOS FETs
same as a regular transistor like a MRF 455? |
bruce
| | Posted on Thursday, January 23, 2003 - 12:41 pm: |
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MOSFETS are a transistor but looks more like a tube when used . They have high Z inputs unlike a normal transistor and can be damaged more easly by a small spark since the gate uses a oxide which is VERY thin. How do they stack up? Nice device they work very well.
MOS FET
Medal oxide semiconductor Field effect transistor |
Moderator558
| | Posted on Thursday, January 23, 2003 - 2:12 pm: |
|
Bruce what do you think of the Yaesu VL 1000P |
bruce
| | Posted on Thursday, January 23, 2003 - 2:59 pm: |
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I have had very good luck with yaseu radios over the years The VL 1000p looks impressive.
Bruce
http://www.qsl.net/ab4oj/quadra/quadra.html
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Tech833
| | Posted on Thursday, January 23, 2003 - 9:31 pm: |
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MOSFETs are very reliable when used properly and will give off less heat for the RF power output due to their lower internal ON resistance.
Almost all broadcast amplifier circuits now use MOSFETs. They are static sensitive, so be careful and ground the equipment well. |
Bigbob
| | Posted on Friday, January 24, 2003 - 7:39 pm: |
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Are power mosfet's the same thing,I heard that compared to regular mosfet's they're nearly indestructible or was someone feeding me hogwash,query? |
Tech833
| | Posted on Friday, January 24, 2003 - 9:11 pm: |
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It depends on the components intended use. A power MOSFET is used as a power amplifier.
Nothing is indestructable. I have had 'indestructable' electronics blow up on my bench millions of times. If they were truly indestructable, there would be no more need for engineers to repair them. |
Mr_Rf
| | Posted on Friday, January 24, 2003 - 9:16 pm: |
|
The advantage that MOSFET's have over bipolar transistors is, as mentioned above, less heat dissipation due to the increased efficiency of the gate biasing. Also to bias the devices for SSB(class AB/AB1) require less brute force current than bipolars thus making them much easier to manage. Frequency response (bandwidth) is much better then bipolars.
And yes, Power MOSFETs are the same, however while they are seemingly more durable than bipolars this is because of the reduced bias requirements during normal operation. An over-driven MOSFET will self destruct quite fast!!!
The VL1000P is a very good amp! |
