Replacement for Foam Filter for PDP 11/24

Fritz Mueller fritzm at
Sat Sep 4 15:40:40 CDT 2021

> On Sep 4, 2021, at 10:42 AM, Rob Jarratt via cctalk <cctalk at> wrote:
> Another query. The foam filter that sits in the front of my 11/24 CPU is
> clearly badly degraded and needs to be replaced. What do people replace this
> kind of stuff with? I guess it mustn't be too fine, this mesh seems quite
> coarse.

Hi Rob,

FWIW, I've used 3M Filtrete (‎FAPF-UCTF2PAMZ) for this application on an 11/34.  It seems I tighter weave than the old foam, but is designed for pretty high airflow and seems to work well.

It's about 1/8" thick, slightly compressible, easily cut to size w/ scissors, and adheres well to velcro hook tape.


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