Hi Howie,
Do you have the paramour II's -- that is the amp that the sr-45 is built on, so I'd also guess that the ps choke would be the triad c7x at 270 ohms. I don't know the value of the cathode bypass cap, and I also don't know what board was used for the shunt reg board/c4s either and if that is still available or not. The amp also requires the pt2 power transformer. Of course I'm talking about the existing SR-45 here, not the new one that will be forthcoming, and I'm not sure which one you're talkiing about. If the latter, it is probably best to wait on the plate choke as this is going to be a critical part of the overall system voltage calculations.
But back to the original sr-45, BH is not releasing the schematics for this anymore, and it may be difficult to get another run of the pt2 power transformers as we just did one last summer. So, in short, a lot to juggle here and it would be premature to jump the gun on too many parts at this point.
A note about the dowdy as it applies to the original sr-45 -- Mike gapped mine for 60 mA instead of the usual 40 mA, which gives an inductance of 80 H vs. 125 H for the original. Mike also expllained that this actually provides better ac and dc balance in the choke specs, and results in a complex impedance that is more favorable for a opt with a 5k load -- such as the exo 4x models. Whether or not this choke, in either form, would be suitable for the new sr-45 is still a big unknown, so I'd wait until the design is out first.
I have the old version and will be using the dowdy gapped for 60 mA in conjunction with the EXo-145 in nickel -- a version of the exo-45 xl with an even larger stack and with the secondaries wound with litz wire, also somewhat more expensive than the standard nickel 45 xls.
So, if at this point you don't have the paramour IIs and instructions and parts for the sr-45 conversion, you'll have to wait for the new design, and nobody but Paul J knows exactly what that will look like yet.
Hope this helps,
Jim
