...snip
>> - In your opinion, Mr. Rauch, do you feel that a Centralab 5kv 1000pF
>> Series 58 is adequate for the 77's load C 160m padder?
>
>It depends on tank Q,
true
>the impedance at the point where the cap is
>located, ...
The circulating current tthrough the load C and tune C are virtually
identical and roughly equal to tank-Q*I-anode.
>and how much C is padding it.
agreed
>1000 pf 58 series caps are not
>generally available in low thermal drift,
large value 58-Series capacitors are not available in low thermal drift
characteristic.
>so they would not be my
>personal choice for that reason alone.
This issue hardly seems to be a matter of personal choice.
- There is about 20A of tank RF circulating current in an amplifier
whose anode current is 2A and whose tank Q is 10. The 58-series
capacitor in the amplifier is rated at 1.4A at 1MHz. Since roughly half
of the tank circulating current flows in this load-C padder at 1.9MHz, it
appears that the amplifier's designer made an engineering error.
Rich---
R. L. Measures, 805-386-3734, AG6K
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