I was thinking about that since there are power1000V 1A or more MOSFET's .
In fact the ideal thing to do would be to also use a pass transistor that turns
off
when clamp is ON to reduce the heat dissipated by a screen dropping resistor.
There are many variations. One could be the clamp could function as a shunt
regulator to maintain a constant screen voltage when signal is applied to the
813s' girds.
Perhaps should not make it real complicated. Using a 807 clamp tube would
retain its classic appeal.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Bill Turner
[dezrat@outlook.com]
Sent: Wednesday, February 18, 2015 12:46 AM
To: Amps group
Subject: Re: [Amps] Biasing a Class C modulated final
------------ ORIGINAL MESSAGE ------------(may be snipped)
On Tue, 17 Feb 2015 21:13:31 -0500, Paul wrote:
>> I am guessing common cathode RF amplifier, a more standard way to do
>> it would be an adjustable bias supply and a clamp tube on the screen
>> grid. (6L6 or similar) look into any pre-1960 ARRL hand book.
REPLY:
A clamp device is a good idea but it doesn't have to be a tube. High
power, high voltage transistors are available dirt cheap anymore. It
will take a little extra circuitry to get the drive right, but that's
dirt cheap too. The hard part is the design.
Bill W6WRT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|