A Rather Obscure Cooling Problem...

[Terminal_Boy]

I'm looking for a fan solution to cool a rectangular RF test chamber of approximately 1/8 of a cubic meter. As it sits in a room which is held at 22˚C, finding cool air to force into the chamber isn't an issue.

Conveniently, the chamber has mounting locations on either side for a 92mm case fan.

The problem is that, for RF isolation requirements, these mount locations consist of a grid of 3.5mm holes piercing the 5-6mm thick sides of the chamber.

Even using static pressure fans, having the fan mounted against a surface which blocks 75-80% of the airflow means that there's very little cool air being pushed into and extracted out of the chamber.

I'm guessing that some sort of stand-off ducting is the answer, but my Google attempts to find something suitable has failed.

Any ideas?

 

[Terminal_Boy]

are you wanting something like this only to convert down to 92mm?

would it be possible to modify the ventilation but still meet the requirements for RF isolation? (for example a larger number of smaller holes), or add additional ventilation mounts?

edit, found the right sized one

only other possibility i could think would be to rig up an air compressor to blast air through the system, although that's not exactly going to be cheap or effecient.

I had seen those, but I don't think they provide enough distance between the fan and the side of the chamber to allow stable airflow.

Alas, modifying the ventilation holes or adding more would reduce the amount of RF isolation, possibly causing local radio interference.

 

[Terminal_Boy]

Just use long bolts with nuts or washers to provide standoffs, and wrap the assembly in duck tape to provide ducting.

That or a suitable cardboard tube could well be my last resort. Thanks.