ORIGINAL MESSAGE:
On Mon, 10 Aug 2009 16:55:58 +0000, Manfred Mornhinweg <manfred@ludens.cl>
wrote:
>
>> I believe that the recommended impedance of the RF choke should be 10 times
>> the plate load impedance of the amp not the reactance of the plate tune
>> capacitor.
>
>It's correct that the load impedance and not the capacitor impedance is
>the base, but the 10 times factor is purely a rule of thumb, and very
>wide deviations are possible.
REPLY:
Ten times the plate load impedance?
For the typical 160 meter amp running 3 kV and 800 mA with a plate load
impedance of aprox 2200 ohms, that would require a choke with a reactance of
22,000 ohms, or about 2000 uH. I have never seen a design with that much
inductance for the plate RF choke, or anywhere close to it..
Are you sure you don't mean 10x the reactance of the tune cap? That seems to be
pretty much the standard.
73, Bill W6WRT
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