active loading with parallel feed? - DanK tubes - MagneQuest/Peerless Forum

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active loading with parallel feed?

I've been looking over Gary Pimm's article on active loads for tubes, and saw his example of CCS loading on an output stage (see link). He uses a CCS above the plate on the output tube to handle the DC current, and a parallel feed output transformer, with a DC blocking cap, parallel to the tube. The triode handles the AC component by working into the load presented by the primary of the output transformer. Now, in the standard parallel feed output transformer configuration, the total inductance is the parallel sum of the output transformer and the plate choke. When you replace the plate choke with a CCS, as Gary shows, there is no parallel inductance component. So the total inductance will be much higher (set by only the output transformer). In my case, a full stack Ni TFA-2004 output transformer will have quite a lot of inductance. Is there any problem with high freq response when operating this way? It looks like a nice idea to me, but I haven't seen may people using this approach. Maybe it just doesn't sound as good? Any thoughts?
Thanks,
Dan

Gary Pimm, active loads (Open in New Window)

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Topic - active loading with parallel feed? - DanK tubes 21:59:00 02/12/11 (13)

how about a gyrator as an active load? - dhsettim 21:17:52 02/14/11 (2)

RE: how about a gyrator as an active load? - DanK tubes 22:38:46 02/14/11 (1)

RE: how about a gyrator as an active load? - dhsettim 21:14:12 02/15/11 (0)

Thanks everyone! - DanK tubes 14:37:32 02/13/11 (0)

RE: active loading with parallel feed? - Paul Joppa 23:33:43 02/12/11 (0)

RE: active loading with parallel feed? - gluca 22:31:43 02/12/11 (7)

Gianluca. Could you calculate a rough estimate of the B+ - Bas Horneman 08:16:04 02/13/11 (6)

RE: Gianluca. Could you calculate a rough estimate of the B+ - mqracing 09:36:50 02/13/11 (4)

Thanks Mike! nt - Bas Horneman 15:29:48 02/13/11 (3)

Using the calculations I arrive at a B+ of around 444V - Bas Horneman 12:09:44 02/14/11 (2)

RE: Using the calculations I arrive at a B+ of around 444V - mqracing 06:07:11 02/15/11 (0)

RE: Using the calculations I arrive at a B+ of around 444V - Bas Horneman 12:15:55 02/14/11 (0)

The planned heatsink - Bas Horneman 08:38:01 02/13/11 (0)

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