Talk of blower capacities lead me to wonder about glass envelope
tubes. Here are some of my questions:
I've never seen an air chimney system used on 3-500Zs. Yet, Eimac
specified the dissipation values given that their air socket and chimney
was in use. In reality, how well does the standard method of blowing air
across the tube work in comparison? Can the full dissipation of the tube
really be obtained, or should the dissipation value be derated? If the
tube dissipation should derated, how can we know by how much?
In their data sheet, Eimac states that the primary limiting factor is the
tube seal temperature. I assume that, ultimately, something else would get
too hot, but this sets the 500 W limit. If one could immerse the tube in
an oil bath, or an otherwise "infinite" heat sink, would the available
anode dissipation be significantly changed? Or, is the limit set by the
thermal transfer coefficient of the glass, meaning that even if the
exterior heat sink were infinite, thermal energy could only be transferred
at a given rate?
Finally, why did Eimac stop producing glass envelope tubes? Was the market
too small to warrant their production, or were there other
reasons? Obviously, other manufacturers think there's a market sufficient
to warrant production.
Kim Elmore, N5OP
Kim Elmore, Ph.D.
"All of weather is divided into three parts: Yes, No, and Maybe. The
greatest of these is Maybe" The original Latin appears to be garbled.
|