[Amps] help with mosfet power amp

Dan Sawyer dansawyer at earthlink.net
Sun Apr 25 18:41:12 EDT 2004


All,

I need help in learning how to handle and bring up a power mosfet amp. I 
have purchased a single stage power amp with 2 MRF154's. The amp has 
three inputs, power, RF in, and RF out. The power input is 50V. I want 
to be careful and not do anything foolish.

1. Can I simply apply 50V to the power input?? About what range should 
the input current be??

2. Is it better to start with 24V??

3. This amp is not broad band across 2 to 50 MHZ. How can the freq range 
be determined?

4. The amp is a 'simple' design and looks similar but is not a copy of 
the Mot. app note. Is it feasible to broad band such and amp? Is freq 
response primarily a function of the input and output transformers??

5. Most MOSFET power amps appear to have an LR feedback circuit from the 
drains to the gates. What is the purpose of this circuit??

Thanks,
Dan






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