27-06-2017, 07:46 PM
Hi Sam,
I'm only needing two valves to complete the lineup. A 2D13C and an FC13C. The 2D13C double diode isn't a problem, it could be replaced with a pair of OA70 germanium diodes or an octal base EB34 double diode. The Mullard Maintenance Manual suggests that the EB34 is a replacement for the obsolete 2D13C. A 33ohm resistor will have be inserted in the heater supply to the EB34.
The FC13C is an octode frequency changer. Grids 1 and 2 serve as the local oscillator. The octal base 6A8G could be considered, this is a pentagrid frequency changer, no suppressor grid. A 22ohm will be required to reduce the heater volts for the 6A8G. Even better if one can be found is the Mullard EK32, like the FC13C it is an octode.
Geordie McBoyne.
I'm only needing two valves to complete the lineup. A 2D13C and an FC13C. The 2D13C double diode isn't a problem, it could be replaced with a pair of OA70 germanium diodes or an octal base EB34 double diode. The Mullard Maintenance Manual suggests that the EB34 is a replacement for the obsolete 2D13C. A 33ohm resistor will have be inserted in the heater supply to the EB34.
The FC13C is an octode frequency changer. Grids 1 and 2 serve as the local oscillator. The octal base 6A8G could be considered, this is a pentagrid frequency changer, no suppressor grid. A 22ohm will be required to reduce the heater volts for the 6A8G. Even better if one can be found is the Mullard EK32, like the FC13C it is an octode.
Geordie McBoyne.
