R. Measures wrote:
>
> On Mar 5, 2005, at 5:23 PM, Tony King - W4ZT wrote:
>
>> Tomm,
>>
>> I believe that what Rich is saying here is that we should treat the
>> GS-35B just as though it were a directly heated cathode when dealing
>> with the question of protection for the cathode and heater circuit. A
>> bifiler choke with a center tapped filament transformer
>
>
> Even though a CT filament winding is required for
> filament-type/directly-heated-cathode tubes, I don't see the necessity
> for heater-type/indirectly-heated-cathode tubes since the heater
> potential is not in the signal path like it is in filament-type tubes.
> ...
<snip>
In the case of the GS-35B, the internal connection between the cathode
and the filament places the heater at RF potential so the RF choke will
be required on both sides of the filament. If you don't use the choke in
both sides of the filament or you ground one side of the filament then
the resistance of the filament will shunt the RF path from cathode to
ground.
73, Tony W4ZT
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