[R-390] Power Supply Modification

Wed, 02 Oct 2002 13:08:59 -0400

Hello,

For solid state rectifiers in the power supply a series 220 ohm 10 watt 
resistor may be added in the common lead to the rectifier cathodes.  The 
official Navy modification calls for installation of the resistor under 
audio chassis.  Excessive heat under the already hot audio chassis is the 
result.  A better location is on the power supply.  I've found it most 
convenient to connect the resistor from the high voltage secondary center 
tap to ground (don't forget teflon sleeve for the leads).

Each rectifier may consist of two 1N4007 in series.

For more information on pros and cons of solid state rectification for the 
R-390x, go to r-390a.net . Select "References" then "Pearls of Wisdom" then 
"Power Supply".  You will find a lively and informative compilation of 
postings to this forum from the last few years.

Drew

>From: "Kenneth G. Gordon" <[email protected]>
>To: "battcharger" <[email protected]>, [email protected]
>Date: Tue, 1 Oct 2002 10:25:33 -0700
>Subject: Re: [R-390] Power Supply Modification
>
> > Could anyone help with suggestions regarding the
> > substitution for both unavailable rectifiers tubes 26Z5
> > for 1N4007 diodes? I think a series 10 W/470 Ohm
> > resistor is needed...
> > Thanking you very much,
> > Sam Rocha
> > PY1 DKW, Brazil
>
>Although the SS mod can be helpful, in addition to the higher
>voltage problem, there can be other problems using them.
>
>For a possible solution to this common problem visit the following
>URL:
>
>http://www.mines.uidaho.edu/~glowbugs/r390_psmod.htm
>
>I have used this mod and it works very well. The tube used for this
>mod is cheap.
>
>Ken Gordon W7EKB

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