Phase Plug design for MW65xx

xschop

I can't do turkey bacon.

Philippians 4:13

xschop

When I get a chance, I'll mod a set of 6502's with these copper shorting rings I made and the aluminum phase plugs. I'll see if I hear a difference or see the same low frequency control behavior as with the focus rings.
Should be a fun experiment...

0.995 OD (Matches Pole Piece)
0.890 ID
0.330 Width

Gardenstater

^^ I can't wait for this Rob! Will there be a small gap between the inside of the shorting ring and the pole piece like I seem to see in all the patent drawings or do you think maybe it doesn't matter and they just drew it that way? Drawings I have seen of the focus ring seemed to have that same gap, incidentally, between the focus ring and the magnet. Whether that matters I also don't know.

Also, I can't help but wonder what the effect would be to machine away a small amount of an aluminum phase plug at the base and put a shorter copper ring on there, maybe electrically insulated from the aluminum?

xschop

To your 2nd paragraph, not sure it will benefit. The alum alloy can corrode quickly being anodic to copper.

Guess I could recess the pole piece area under the ring since it wont be in the gap. To me that removes more steele mass from the flux equation. Will it be a benefit or detriment?

Gardenstater

I think that, if a small copper ring was tried at the base of the aluminum phase plugs it could be a slip fit; maybe a loose one, and ample loctite could be used between the ring and the phase plug. That would solve the problem of dissimilar metal corrosion and should give electrical isolation to keep it as a clean high-conductivity shorted turn whose resistance and frequency behavior are predictable and not diluted by parallel paths through the aluminum. Aluminum is about 61% of the conductivity of copper.