[R-390] Selenium Rectifier

[Bonddaleena at aol.com]

In a message dated 11/15/2005 7:28:49 PM Eastern Standard Time,  
jpl15 at panix.com writes:



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

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I bought a huge 6 Meter amp back in the 80s. In the PS, there were 4 of  
these 'stacks'. Each leg had about 50 diodes! At first, I thought they were  
selenium, then I realized the previous owner had used metal diodes, fitted to  
those cooling fins, then he painted the whole thing red. Each diode has an  
equalizing resistor and cap across it. It must have taken weeks to build  
it....Looked cool. 
I later swapped it for 4 of those K2AW potted rectifiers. I don't see any  
difference.
 
ron
 
N4UE