Return to: Talking Dog Transducer Company Home Page

Restoration Examples Page
RCA 77-DX & RCA BK-5B Ribbon Mics - (See below for the "Before" & "During" pictures)
The "After" Pictures:

AND:  An RCA BK-1A Dynamic & KS-11 desk stand:

The BEFORE & DURING Pictures of the above 77-DX & BK-5B:
The pictures don't really do justice to how bad these were.  On the 77-DX, the surface rust on the center label ring meant removing the nickel plating (note it's brassy appearance in the disassembled picture below), as did removing the rust, oxidation & pitting on the shock mount parts, yoke thumbscrews & cable clamp.  This mic prompted me to learn how to do auto-catalytic nickel plating.  On the center body, which is a bakelite cylinder that is riddled with holes inside to form a transmission line labyrinth, the top section had been covered with a piece of copper sheet metal, to hide a 2.5 inch long section of the top edge that was chipped out.  I removed the plate & re-constructed the chipped out section, then primed & repainted the entire body (to the proper color).  The bottom housing was pitted from oxidation so badly that I had to get it sandblasted.  Then, I polished back to it's original shine.

The BK-5B shows it's damage pretty well.  It was mainly just a matter of stripping every bit of paint off of every part, polishing out the oxidation pitting, then priming & painting.  The trickiest part of doing a BK-5 is the ribbon installation & tuning.  It's ribbon has a width of 0.052", vs the 77's 0.056".  Not a big difference, but the BK-5 has much less clearance between the ribbon & the walls of the magnet gap, making it much much harder to keep perfectly centered during clamping & tension tuning.  In the pictures below, note the ingenious use of the outside wall of the BK-5 center body to create the labyrinth, necessitated by the fact that the transformer & low cut inductor occupy the middle space.