How to bias a MOSFET amp?

[Dbowey]

John posted:
<< On Sun, 29 Aug 2004 19:34:57 +0100, Paul Burridge

Toobz? I was talking of transistors. Many tranny designs for Class C
RF utilize self-bias, too, but there is still no quiescent current!

What makes an amp Class C is a low conduction angle while operating.
When it's not operating, is has no class at all.
I can't recall any reference to support your last paragraph, but I have many
experiences to refute it.

Many, if not most, Class C amplifiers remain "on" while not transmitting; That
is, their Class C bias holds the control grid sufficiently negative to hold the
tube in cutoff when there is no excitation. When excitation is resumed, the
tube conducts. Obviously it is in Class C at all times.

Don

 

[John Larkin]

John posted:
<< On Sun, 29 Aug 2004 19:34:57 +0100, Paul Burridge



What makes an amp Class C is a low conduction angle while operating.
When it's not operating, is has no class at all.

I can't recall any reference to support your last paragraph, but I have many
experiences to refute it.

Many, if not most, Class C amplifiers remain "on" while not transmitting; That
is, their Class C bias holds the control grid sufficiently negative to hold the
tube in cutoff when there is no excitation. When excitation is resumed, the
tube conducts. Obviously it is in Class C at all times.

Don

How can an amplifier be a Class C Amplifier if it's not an amplifier?

What's the difference between a totally cutoff class A amplifier and a
totaly cutoff class B amplifier?

John

 

[Ken Smith]

How can an amplifier be a Class C Amplifier if it's not an amplifier?

When dragon sleeps it still dragon, grasshopper.

What's the difference between a totally cutoff class A amplifier and a
totaly cutoff class B amplifier?

Trick question! If the amplifier is totally cut off it isn't a class A
amplifier.

 

[John Larkin]

When dragon sleeps it still dragon, grasshopper.

But when a waterfall is dry, it's just a pile of rocks.

John

 

[Dbowey]

John Larkin posted:

John posted:
<< On Sun, 29 Aug 2004 19:34:57 +0100, Paul Burridge



What makes an amp Class C is a low conduction angle while operating.
When it's not operating, is has no class at all.

I can't recall any reference to support your last paragraph, but I have many
experiences to refute it.

Many, if not most, Class C amplifiers remain "on" while not transmitting; That
is, their Class C bias holds the control grid sufficiently negative to hold the
tube in cutoff when there is no excitation. When excitation is resumed, the
tube conducts. Obviously it is in Class C at all times.

Don

How can an amplifier be a Class C Amplifier if it's not an amplifier?

What's the difference between a totally cutoff class A amplifier and a
totaly cutoff class B amplifier?How? An amplifier amplifies when it is driven by an appropriate signal. The
appropriate signal to drive the Class C amplifier is an RF signal from a driver
stage.

What's the difference? A Class A amplifier amplifies through 360 degrees. In
normal use it is *never* cutoff.

A Class B amplifier is *normally* biased so it is cutoff or has low idle
current with no signal applied, and conducts through 180 degrees with signal.

The Class C amplifier is biased to cutoff with no signal applied, and with
signal applied, conducts for less than 180 degrees and may be set to conduct
for as little as 90 degrees.

Why do you believe a Class C device is not an amplifier?

Don

 

[keith]

Burridge? <shudder>

 

[John Larkin]

Burridge? <shudder>

He said surgeon, not sturgeon.

John

 

[John Woodgate]

I read in sci.electronics.design that John Larkin <jjlarkin@highSNIPland
THIStechPLEASEnology.com> wrote (in <7fo6j05rp857et2n7tbqlp12bavl48qrrv@
4ax.com>) about 'How to bias a MOSFET amp?', on Mon, 30 Aug 2004:

He said surgeon, not sturgeon.

But, being male, PB is not even a potential source of caviar.

 

[Paul Burridge]

I read in sci.electronics.design that John Larkin <jjlarkin@highSNIPland
THIStechPLEASEnology.com> wrote (in <7fo6j05rp857et2n7tbqlp12bavl48qrrv@
4ax.com>) about 'How to bias a MOSFET amp?', on Mon, 30 Aug 2004:


But, being male, PB is not even a potential source of caviar.

Hey ladies, gimme a break will ya? Don't make your PMS my problem. ;-)

 

[John Fields]

I read in sci.electronics.design that John Larkin <jjlarkin@highSNIPland
THIStechPLEASEnology.com> wrote (in <7fo6j05rp857et2n7tbqlp12bavl48qrrv@
4ax.com>) about 'How to bias a MOSFET amp?', on Mon, 30 Aug 2004:


But, being male, PB is not even a potential source of caviar.

 

[keith]

I read in sci.electronics.design that John Larkin <jjlarkin@highSNIPland
THIStechPLEASEnology.com> wrote (in <7fo6j05rp857et2n7tbqlp12bavl48qrrv@
4ax.com>) about 'How to bias a MOSFET amp?', on Mon, 30 Aug 2004:


But, being male, PB is not even a potential source of caviar.

OTOH, he's a good source of other slime. If you want ot go there, be my
guest!

 

[keith]

Hey ladies, gimme a break will ya? Don't make your PMS my problem. ;-)

Paul's Miserable Shit?

 

[Rich Grise]

Paul's Miserable Shit?

Psychotic Male Syndrome.