In article m,
A wrote:


On Tue, 1 Apr 2008, Rick wrote:

How long after applying filament voltage till the 813 is ready to transmit?
Is it like a 3-500 or do I have to wait 30 seconds or so?


When the glow is up to bright orange, then you are ready. If you apply the
filament voltage without "management" (i.e. a slow increase over, say 5-10
seconds), the tube should be ready for transmit in, like, about 1-2
seconds. In a heater cathode (rather than a filament cathode), you need to
wait for that thin "coat" to come up to a dull orange and that can be half
a minute or so depending on the tube.

Note that slow turn-on will radically increase the lifetime of these tubes
if you're using them below full power level. An inrush current limiter
in series with the filament only costs a dollar or two and can easily pay
for itself a hundred times over.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."