[R-390] Selenium Rectifier

[John Lawson]

On Tue, 15 Nov 2005, DW Holtman wrote:

> Hello,
>
> Does anyone know where I might buy a Selenium Rectifier for the chassis of a 
> R-390A, CR-102. I have replaced it with a solid state bridge for now, but 
> would very much like to get something more original in the chassis.  I could 
> not figure out a clever way to hide the diodes inside the selenium fins.

  It was common some years back to mount rectifier diodes in a finned 
assembly like a selenium.  The diodes (the stud-mounted kind) were affixed 
to on of the fins, and the diode body protruded upward through holes in 
the adjacent fins (for clearance). The top lead of the diode was then 
attached to whatever fin it was closest to.  The fin that the diode 
mounted on had a solder tab, and the fin the anode lead mounted to had a 
tab.

   I have several of these assemblies with 4 and 8 diodes per "stack".  You 
might be able to disassemble the original selenium stack - they were 
either bolted or riveted - and then using a Whitney hand punch - punch, or 
drill, holes in the fins sufficient to mount the diodes. Actually if you 
used samll epoxy radial diodes, the holes could be quite small in the fins 
- then just bring out leads or make solder tabs, insulated with teflon 
washers.

   Just an Idea....


Cheers

John  KB6SCO