EMRFD Message Archive 14352

Message Date From Subject
14352 2017-09-25 08:47:48 mosaicmerc Tenasitor input impedance.

I was reading up on designing HF amps here:
http://sm0vpo.altervista.org/tx/rf_pa_cct_00.htm

and a it mentioned a rule of thumb for bipolar input impedance is equivalent to the Emitter resistor.
What would be the rule of thumb for MOSFEts?.

14354 2017-09-25 10:53:47 Ashhar Farhan Re: Tenasitor input impedance.

you might as well divide your age with the shack's temperature. this rule of thumb is useless. The correct answer is, of course, it is 'complicated'. but nothing is more enriching than sitting down with the first five pages of EMRFD's second chapter. that has the answer. it is not 42.

- f

14352	2017-09-25 08:47:48	mosaicmerc	Tenasitor input impedance.
Message	Date	From	Subject
I was reading up on designing HF amps here: http://sm0vpo.altervista.org/tx/rf_pa_cct_00.htm and a it mentioned a rule of thumb for bipolar input impedance is equivalent to the Emitter resistor. What would be the rule of thumb for MOSFEts?.
14354	2017-09-25 10:53:47	Ashhar Farhan	Re: Tenasitor input impedance.
you might as well divide your age with the shack's temperature. this rule of thumb is useless. The correct answer is, of course, it is 'complicated'. but nothing is more enriching than sitting down with the first five pages of EMRFD's second chapter. that has the answer. it is not 42. - f