On Wed, 8 Aug 2001 18:32:19 -0700, Paul Hewitt wrote:
>Hi Bill
>IMHO the best way to control bias/cathode current
>is by means of solid-state switching. It will be
>faster than either I/O relay operating at <2ms
>make and <1ms break. The bias (on/off)control
>transistor operates saturated so a little goes a
>long way dissipation wise. I use the same control
>buss for I/O relay control and bias switch.
>Paul
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I agree about solid-state switching, but IMO, the tube should be still
biased off until switching is complete, both input and output.
Otherwise, the tube could see a brief unloaded condition, which has been
known to cause trouble.
True, many amps are stable in an unloaded condition, but every amp
manual I've seen advises against it. I'd just rather be safe than
sorry.
Bill, W7TI
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