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In Reply to: RE: II. Power Supply posted by Paul Joppa on December 06, 2014 at 17:55:37
On the topside of my chassis I have the PT-choke-OPT all in a row along the back. The chassis is kinda small in an attempt to keep it rigid.
The choke and OPT are potted, so hopefully they will be OK.
The 156C can go underneath toward the front in a corner close to the 6J5 and/or 2A3.
I will try your suggestion to use the DMM to see if I can find a sweet spot for the 156C. I do have to order these first though.
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Hey Garg0yle, years ago a company called Welborne Labs came out with a DRD style amp (similar to the Monkey). You can find chassis layout photos on line if you poke around. They had both a solid state and tube rectified version of it. IIRC it could be ordered for a 45, a 2A3 or a 300B. It was reported to be very quiet.
I actually picked up a couple of those chassis from Welborne on a clearance one time...always wondered how to figure out the placement of the items 'under the hood'...think I might add a "BB proof half monkey ala DRD chassoise" to my hot stove on deck circle...
If you go to their website (still in business I guess) you can buy a PDF of the construction manual. I did it weekend but it didn't open, but a day later they sent me an email copy. Anyway, clearly Paul's circuit is different / better, but this is a great guild to the layout.
re: "...clearly Paul's circuit is different / better", mine is nearly identical in conception - I bypass the 2A3 cathode resistor instead of the driver cathode resistor; that's about it. The topology is so simple, there are few variants possible.
Mostly what I have tried to offer here is some specific parts values as a help in getting started, and a description of how they were chosen for those who want to make modifications. Plus of course I could not have put someone else's commercial design in the public domain!
Thanks.
OK so I had a look at a few of the Welborne DRD via google image search.
My layout is similar, the differences being:
-I have my choke jammed in between the PT and OPT on the topside.
-The 2A3 is in between the input tube and rectifier, placing the 6J5 on the opposite end of the power supply area. (Although I see some variations, both 2 and 3 tube versions of the Welborne DRD)
-The plugs and terminals are going to be along the "long" side of the chassis. The long sides on mine will be the front and back. I pondered turning them 90 degrees like the Welborne, but I will leave that for now as I don't see an apparent advantage to do so at this point.
Although I might put the power switch near the IEC socket like the Welborne has. I haven't had a problem with front mounted power switches in the past, however I think it might be prudent on this one.
I don't know what the orientation is of my OPT and choke though, since they are enclosed. I will orient these by their lead-outs at the bottom to minimize crossed wires etc.
I noted the plate choke on the DRD appears to be on the "front" wall near the tube sockets, similar to where I will place mine.
Given the size of my chassis the layout is fairly decent, time will tell.
If it doesn't work out I would have to go to a bigger chassis as opposed to rearranging the 12"x8"x2" chassis I have now.
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