ORIGINAL MESSAGE:
On Sun, 8 Nov 2009 18:43:18 -0500, "Carl" <km1h@jeremy.mv.com> wrote:
>
>I'll repeat one more time. The dinky diode doesnt prevent tube and circuit
>damage, it shorts after the damage is done.
REPLY:
You are half right.
I agree it won't prevent tube damage, but it will indeed prevent damage caused
by the B- line being driven to the full HV negative with respect to ground.
Think about a negative 3000 volt pulse being coupled back through the input
circuit to the output of your transceiver. Think about a negative 3000 volt
pulse appearing on the cathode of your tube if the filament is DC grounded. If
the filament is connected to the cathode, think about a 3000 volt pulse applied
to the secondary winding of the filament transformer. Think about the tube
socket, the tuning caps in the input circuit, etc, etc... Few if any of those
components will withstand the full HV. Get the idea?
Thank goodness for the dinky diode! :-)
73, Bill W6WRT
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