One thing to remember about the 3CPX5000/ YC156 is if you use
the same filament choke for the cathode connection as for RF you
will likely pick up some low level hum from AC voltage drop in the
The easiest solution is to use a separate choke for cathode return.
Do not use the filament choke for cathode return, unless you add a
hum balancing circuit.
73, Tom W8JI
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