Choke placement...

[Brownie]

Would it be unwise to situate a choke within a 1/2" of the power transformer? Will they "talk to" each other or contribute to hum? I want to hide the choke inside the chassis above the endbell of the PT. Is this feasible?

[acheld]

You can "probably" get away with that.

The main thing is to make sure that the magnetic fields of each device are orthogonal to each other.   In other words, if the steel laminated core of the choke and the PT are lined up the same way, that is "bad." 

I've never kept a choke inside a chassis due to space constraints and the fact that it would introduce EMF inside the chassis.  Edit per Wim's reply:  Since I use aluminum chassis's the latter probably makes little sense.

Let us know how it turns out, with a photo please . . .

[tdvt]

You can "probably" get away with that.

The main thing is to make sure that the magnetic fields of each device are orthogonal to each other.   In other words, if the steel laminated core of the choke and the PT are lined up the same way, that is "bad." 

I've never kept a choke inside a chassis due to space constraints and the fact that it would introduce EMF inside the chassis.  Since I use aluminum chassis's the latter probably makes little sense.

Let us know how it turns out, with a photo please . . .

So..


I DID do as Brownie proposes, maybe even one step further, & mounted everything inside the chassis on a 6G15 stand-alone reverb unit, as I was more concerned about the reverb tank picking up hum from the transformers, as the cabinet would be quite small.

Good results, no noise, but probably not something I would do as standard practice.

This does use a toroidal PT, which could also figure in.


Exception to every rule & all that....

[WimWalther]

Since I use aluminum chassis's the latter probably makes little sense.

The fact that the chassis is aluminum has little bearing on this. While Al isn't ferromagnetic, it's still a very good electrical conductor.

The varying magnetic field leaking from a transformer or inductor is just as capable of inducing a field in aluminum as it is in steel, copper, nickel, etc.

Ever seen the demonstration where a strong magnet is dropped into a copper pipe? Or a magnet is slid down a sheet of copper or aluminum?

[Brownie]

Thanks for the advise, but it looks like there isn't any need for me to hide it inside. It takes the real estate up on either side, so I'll hang it beside the PT. This is in an old 16" Garnet chassis that's my testbed. Building a second 6V6 "Plexinstein"

[WimWalther]

Here's a very brief video that demonstrates the interaction between a strong magnet and copper tube.

The motion of the magnet induces an circular current in the copper tube on the order of hundreds of amps, or more. This current, in turn, produces a magnetic field - a counter-EMF - that directly opposes the motion of the magnet (Lenz' law).

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