800W Load - Rackmount

[kenpeter]

I bolted everything to the underside of a slide out shelf...
When not in use, slides fully into the rack, dissapears, and
becomes a normal shelf. But havn't wired anything yet.

The front is organized for series & parallel bus wires to go
through the posts sideways. The hole in the side of each
binding post is the same size as the hole in front.

So, anyways: This is Qty8 of 4ohm 1% non-inductive 100W.
Lead times and prices on >100W were unreasonable, so we
settled for several 100W that can be reconfigured as needed.
These Dales came from Newark.

I used bolts that would normally be countersunk, such that
the top shelf surface is still reasonably flat and unobstructed.

[thaumaturge]

Nice work.
I think such resistors expect some surface heat transfer to make full wattage. Don't know if they will do full spec with just freeair dissipation. A bit of heat sink compound between resistor and chassis will definately help. Just a thought. Also, if you are going to opperate in flip up attitude, a small plastic or sheet metal tent over each resistor will help promote chimney effect free air cooling.
Doc

[cyclecamper]

I'm surprised you didn't bolt them to an aluminum heat-sink with a fan on it.

[5th element]

Indeed resistors like that can dissipate much more power on heats-inks.

[kenpeter]

The shelf is plenty big enough for a box fan when deployed

[nigelwright7557]

A resistor load is fine for testing.

I would always also test using speakers as they are a more inductive and capacitive load and can cause an amplifier to oscillate.

[thaumaturge]

Originally Posted by kenpeter

The shelf is plenty big enough for a box fan when deployed

As I said first in my comments: Nice work!
Doc

[kenpeter]

Originally Posted by nigelwright7557

A resistor load is fine for testing.

I would always also test using speakers as they are a more inductive and capacitive load and can cause an amplifier to oscillate.

When I have a procedure to follow that calls
specifically for measurements with resistors,
resistors have to be used.

I opted for non-inductive resistors at extra
cost, cause you can always add inductance.
But darn hard to make it go away.

We have speakers too.

[5th element]

I suppose it depends. I have some high power resistors like that bolted to a large heat-sink and on sustained high power tests the sink gets really hot. I am sure that you could easily increase the total sustained dissipation capability by using a better method for cooling, but whether or not this is needed is another matter entirely.

[kenpeter]

If it needs more of anything, it will get more.
For now, this is probably slight overkill.

Don't go over-imagining that I would use this
at full power 24x7. Its for production testing,
not solid weeks of burn-in or characterization.
Our customers have their own labs for that.

If you are building a load for sustained use,
those considerations are probably relevant.