Up for sale here is this NOS vintage US Army Signal Corps 3Z1892-5.1 filter, made by the United Transformer Co (UTC).  This is probably WWII-era or 1950s.  It is unused but has some wear and paint loss from age and storage/handling.  This is guaranteed to work.  Please see my pictures for details.

US shipping and handling is $10, and international is $36. If you have any questions, please ask.

I have more transformers and other vintage electronics listed--feel free to take a look!