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On 8/25/05 at 5:14 AM R.Measures wrote:
>On Aug 25, 2005, at 4:52 AM, Roy Koeppe wrote:
>
>> If...
>>
>> "Reactance at 1.8MHz = 3099 Ohms"
>>
>> Then,
>>
>> With 3 kv on the plates, circulating current through the choke winding
>> and through the by pass cap is 1 amp?
>
>With a 3kV anode supply, The peak change in anode potential is c.
>2700v-pk 0.707 x 2700v = c. 1900V-rms, so the circulating current
>through the HV-RFC is 1900v / 3099-ohms = 0.616A-rms
Most of the time in engineering, one tries to at least double the working value
if possible. So one that would handle 1-1.2 amperes would be what to use.
>>
>> You see, this is a useless parameter.
>
>Not quite since the HV bypass C must be able to carry 0.616A at 1.8MHz
>without overheating and igniting.
I've seen that happen, plus they do stink to high heaven when they burn, about
as bad as an electrolytic. Some of those high capacitance TV doorknob types
wont handle the current and are bad to go POOF!
>
>> Circulating current is limited by
>> parallel resonances in the winding,
>
>At 1.8MHz, with a typical Ham amplifier - I don't think so.
>From 80 to 10 meters, the self resonant frequency is all you have to worry
>about that I've seen. As long as the choke has enough inductance for the
>lowest frequency, it should work, providing its SR is not on an operating
>frequency.
>
>> which present a much higher
>> effective resistance to the tank circuit.
>>
>> 73, Roy K6XK
>>
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>>
>>
>
>Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>
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Best,
Will
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