[Amps] 8877 amp- to ground fil ct or not?

[Bill Turner]

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On Tue, 5 Jun 2018 13:08:14 -0700, N6CFH wrote:

>
>Asking for current thoughts on grounding the filament CT on 8877. Have seen
>both ways utilized.
>
>How about connecting cathode to one filament lead? Again, have seen it both
>ways.

REPLY:

As you say, both ways work so I believe the best practice is to leave
the heater "floating" i.e. not connected to the cathode. This avoids
the need for a bifilar choke in the heater leads in a cathode driven
(grounded grid) design. 

The only drawback to this is the possibility of the tube developing a
cathode to heater short which would disrupt the input impedance, to
say the least.  The 8877 has plenty of insulation between the cathode
and heater and this should never be a problem. 

73, Bill W6WRT