The AM Forum

I am rebuilding a 1930's Frankenstein-ish high power AM transmitter built on open racks and the builder used many porcelain chassis feed through insulators for the intercabling between rack decks.  Over the past 80 years and innumerable moves, some of these have become broken.  I have exhausted my own junkbox and still need some.

The originals are marked "Birnbach 4125" and are as shown in the photo here.  About 3/4 inch diameter at the base with a 1/2 inch opening.  The surplus stores used to have buckets of these but today the surplus stores are gone and so are the buckets.  These must exist in someone else's junkbox.  Not sure how many I need exactly, 6-8 possibly.  Don't let me have to sign up for a ceramics class at the local JC and make these things, no good can come of that.

See photos below, one of the insulator and the other of Frankenstein.

Here are some more photos