At 08:36 AM 12/12/97 -0800, you wrote:
>There are no smallish wires in the the grid of an 8877. There are 100+
>rectangular bars. At Eimac's maximum ratings of 4000v and 250MHz, the
>grid of an 8877 carries over 40 RMS amperes. // There are no small
>wires in the 8877 cathode element.
Great to hear that, Rich! Most of my amps are 8877's so I have a broad
cushion with the 4 Joule limited anode supply. It was not the intent
of the Eimac paper to cover each tube type individually. The 4 Joule
limit was devised as a blanket value to cover ALL their small TX types.
I am sure some of the smaller glass tubes are closer to disaster at the
4 Joule limit than an 8877, but the blanket recommendation covers all
of their smaller tubes in one whack. As I mentioned earlier, the 3CX3000A7
and larger tubes are allowed a limit of 50 Joules. They seem to make
the 4 Joule/50 Joule dividing line at 2000-3000 watt dissipation tubes.
This gives us only 2 numbers to remember when designing the glitch
resistor for a power supply.
(((73)))
Phil, K5PC
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|