On Apr 24, 2004, at 10:51 AM, jeff millar wrote:
Things to think about
- Cold resistance much lower than hot, PS may fold back on overcurrent
and never light up the tube
Good point, Jeff. The cold-R of a 3-500Z is 8.3x less than the
hot-R.
- Add some series resistance to limit surge current when cold...For
example, a 6V supply with 1V of drop across the RF choke
- Alternatively could arrange a soft start circuit to ramp the voltage
and minimize cold current.
- With DC on the filament, the Grid to cathode bias varies along the
filament the same way, which causes more emission from one end of the
cathode than the other. Some people talk about reversing the filament
connections periodically to even out the wear.
- Very easy to adjust filament voltage lower for better life at your
emission needs.
jeff, wa1hco
...
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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