A cheap way to do it is the way Rich says below. Actually you can use
both his techniques in his two posts. Use the rectifier (1N5408) string
for the adjustable bias, and the resistor in series, shorted with a
relay to cut the tube off on idle.
Will Matney
On Oct 4, 2004, at 7:33 AM, Bill Turner wrote:
On Mon, 4 Oct 2004 01:58:50 -0000, Barry Kirkwood wrote:
Beats me why people buy high watts zeners to set the bias of
amplifiers when
there is a better and cheaper way.
_________________________________________________________
High power zeners are nearly bulletproof when it comes to brief
overloads, power surges, spikes, arcs, etc, etc. Your low power
transistor-and-zener approach seems a bit risky by comparison. And if
you use a really high power, high voltage transistor, what have you
saved? Power zeners are pretty cheap anymore.
- A string of 3A Si rectifiers is cheap and they are adjustable in
0.7v steps by moving the tap. However, a power zener is not
adjustable. A 3A rectifier will withstand 200a peaks. Can a power
zener handle 200A?
KISS is Murphy's worst enemy. :-)
Those who ignore Murphy are their own worst enemies. Cheerz, Bill.
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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