Paramount Soft Start in Parabees

[AudioDave]

I am seriously thinking of rebuiding my Parabees in order to get them in a bigger chassis  (was thinking of using my spare Paramount chassis plates)  As part of the rebuild I would like to install the Paramount soft start boards.  Would this be very difficult to do?
Thanks!
Dave

 

[Paul Joppa]

It should be fairly easy, especially if you follow the Paramount layout. The biggest difficulty would be fitting the plate choke which is a bit larger.

I'd take the opportunity to upgrade the power supply, if it were mine - the voltage rating on the high voltage diodes and the filter caps is marginal. I've posted before a DC filament scheme which you might want, if hum is an annoyance.

 

[xcortes]

I have the Parabee plate choke (exo-03)  in Paramounts and Paramour 2s. There's pics around. I place it centered to the PT and slightly rotated so that it fits.

 

[AudioDave]

Thanks for the replies!  Looking forward to the rebuild!
Dave

 

[AudioDave]

Paul,  when you say "upgrade the power supply"  what exactly are you referring to,  upgrade the components in the existing Parabee designed ps,  upgrade the power transfomer?
Thanks!

 

[Grainger49]

The transformer is fine, he means the caps are old, probably too low a voltage for today.  The diodes are probably too low a voltage (PIV) too.

 

[Paul Joppa]

Grainger is exactly right.

If it were me, I'd use the Cree 1200-volt silicon carbide Schottky diodes, but something as simple as two UF4007s in series for each diode will give you the margin.

If you keep the power supply filter choke, then you can get away with smaller capacitances, such as 47uF/600v film caps. In the current Paramount we use two 350v caps in series for each cap.

 

[AudioDave]

Excellent!  Thank you very much!
Dave

 

[AudioDave]

Since I am expanding into a bigger chassis I was thinking of adding a separate power transformer for the DC filaments.  Any suggestions?