Mystery Tube Adapter (Collins?) 5750/6BE6

$35.00

Here's a total mystery adapter (or filter). This was in a box of Collins-branded filters, but this one has no marking of any kind, inside or out. Goes into an 8 pin tube socket, same as the Collins filters.

This is what I know of this mystery adapter. Photos show outside, and all views of the parts inside.

Sold as is, for parts or repair.