Tube Rectifier

18watt-specific Tech Talk - Building, Fixing, Parts, Mods...

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djunks2
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Tube Rectifier

Post by djunks2 »

Just started my 18 Trem this weekend. Man, talk about cramming a lot of stuff into a small space. The chassis I've used for my home audio amps are mansions compared to the guitar stuff. Not to mention those darn little 9 pin sockets. Anyway...I'm building from a kit and the wiring schematic and PT transformer it came with are meant for a CC rectifier. I'm using a NOS 6CA4 along with some other great tubes I got from the Sarge. I've searched the forums and I think I've found info that says it's alright to use the "one-and-only" :hmm: 6.3 volt tap for the rect. heaters along with the rest of the tubes. True??
Happy Holidays BTW.
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MagicMan
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Post by MagicMan »

No problem. The 6CA4 has an indirectly heated cathode. Tubes like 5Y3 and 5U4 have directly heated cathodes and require a dedicated filiment winding.
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tubetek
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Post by tubetek »

Weeeeellllllll....
You are both partially correct:
The filament is 6.3vac AND indirectly heated; what makes it safe to share the filament heater winding with the other tubes is that the cathode of the 6CA4 is NOT internally connected to the filament as it is in most common rectifier tubes (GZ34/5AR4, 5Y3, 5U4 etc) therefore there isn't B+ riding on the filament winding and zipping straight to ground via the filament CT or ground-reference resistors...ZZZZZZZAP!!!
Hope this helps and enjoy the Holidays!
tubetek
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what_wires
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Post by what_wires »

tubetek wrote:Weeeeellllllll....
You are both partially correct:
The filament is 6.3vac AND indirectly heated; what makes it safe to share the filament heater winding with the other tubes is that the cathode of the 6CA4 is NOT internally connected to the filament as it is in most common rectifier tubes (GZ34/5AR4, 5Y3, 5U4 etc) therefore there isn't B+ riding on the filament winding and zipping straight to ground via the filament CT or ground-reference resistors...ZZZZZZZAP!!!
Hope this helps and enjoy the Holidays!
tubetek
Which is exactly what MagicmMan said, only he used 90% fewer words :roll: :roll:
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