[R-390] Solid State rectifiers vs Tubes

[Kenneth G. Gordon]

On 18 Sep 2002 at 14:37, Scott, Barry (Clyde B) wrote:

> List,
> 
> I was looking over the changes to the HP200CD audio signal generator
> and I found where they went from solid-state rectifiers to a tube
> rectifier.  That seems rather odd to me.  Why would they have decided
> to go back to a tube rectifier?  The change notice included distortion
> figures.  Would a power supply configuration with a tube versus
> solid-state diodes have lent itself to a cleaner signal?

It certainly could have. SS rectifiers cut off so sharply that they 
generate a goodly amount of noise, kind of like a spark-gap. I 
ALWAYS bypass for RF any I install. Disk ceramic caps both 
"across" every diode, and sometimes, depending on the noise 
problems I have with them, from each end to ground.

Tube rectifiers generate inherently quieter DC...except mercury 
vapor types, of course, but even those can be taken care of easily.

I have had considerable problems with noise from SS rectifiers 
getting into my receivers.

For the R-390 or R-390-A where one has trouble getting those 
26Z5s, you all might consider changing them to 12BW4s. 

For details go to:

http://www.mines.uidaho.edu/~glowbugs/

and click on link # 10.

Ken Gordon W7EKB