layout sanity check

a DIY, modified Mullard 5-20 monoblock design

layout sanity check

Postby bootsie » Sat Feb 28, 2015 4:56 am

Hi DiyTubers,

I'm at the stage where I need to think about drilling my chassis. At the moment I'm going with a Hammond 16x8x2. This is my proposed layout:

top panel layout.png
top panel layout.png (10.08 KiB) Viewed 2383 times


The Output transformer at the rear of the chassis (on the left of the image), the Power transformer and Choke at the front (on the right of the image).
I've planned for the choke (the C-24X) to sit underneath the power transformer. I'm concerned about magnetic coupling between the two. Does anyone know the axis of the windings on the Hammond 374BX and the C-24X?

Is this layout going to cause me any problems, or am I best moving the choke away from the power transformer? It seems to be neater this way but I don't want to compromise anything just for aesthetic reasons.

Steve
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Re: layout sanity check

Postby Shannon Parks » Sat Feb 28, 2015 11:53 am

Hi Steve,

I've placed a choke under a PT in many designs that I never actually built (FPE brainstorming). I think you'll be A-OK. But consider countersinking the choke holes and using flathead screws there.

Are all the other connections going on the rear?

Shannon
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Re: layout sanity check

Postby bootsie » Sun Mar 01, 2015 9:26 am

Thanks Shannon. I have some 6/32 buttonhead screws that are a really low profile and look like they sit under the PT ok (as the core is slightly raised from the mounting tabs anyway) but if it doesn't fit I'll go with your countersink idea, good call.

Yes, all connections on the rear. RCA input one side, switched & fused IEC power inlet the other, speaker binding posts between the two. I'll post some pictures up of my progress, everyone likes pictures right?
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Re: layout sanity check

Postby Jimster41 » Sun Mar 08, 2015 7:24 am

So I notice you are using a larger P. Transformer. Is that because you want to be able to run KT88's. Will the 274BX run KT88's w/out getting hot?
I want to be able to do that as well (run KT88's) and I'd like to have the option of running one or two lighted current or voltage meters.I was assuming that could be done off the third (5V) tap?

Also any downside or upside to going with the "potted" series PT?
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Re: layout sanity check

Postby bootsie » Wed Mar 11, 2015 8:33 am

Jimster41 wrote:So I notice you are using a larger P. Transformer. Is that because you want to be able to run KT88's. Will the 274BX run KT88's w/out getting hot?
I want to be able to do that as well (run KT88's) and I'd like to have the option of running one or two lighted current or voltage meters.I was assuming that could be done off the third (5V) tap?

Also any downside or upside to going with the "potted" series PT?


The only reason I'm running a 374BX is that it's a Universal Primary and I'm in the UK - the 274BX is 115v only. Yes, I'm going to be running KT88s but I haven't changed any of the parts (other than I'll be biasing higher). Hopefully that won't cause me any problems - I'll find out soon.
With regards to your other questions - no idea!
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