[Hallicrafters] Solid State rectifiers vs Vacuum Tube rectifiers

[jeremy-ca]

If the filters are original a surge limiter would be beneficial but of no 
use if replaced with modern caps. The transformer surge current is limited 
to the flux density of the core. Since the receiver manufacturers counted 
every penny there wont be any excessive draw at turn on.

Even a slight bit of higher B+ wont harm anything since the USA AC mains 
were anything but standardized in the old days. Anything from 105-117 or 
more was the norm. The danger is to the tube emission; oxide coated cathodes 
can be seriously harmed when the filament voltage exceeds more than 5% or so 
over design spec.

Carl
KM1H


----- Original Message ----- 
From: <HallicrafterSX28 at aol.com>
To: <Hallicrafters at mailman.qth.net>
Sent: Saturday, September 08, 2007 4:13 PM
Subject: [Hallicrafters] Solid State rectifiers vs Vacuum Tube rectifiers


> Solid State Rectifiers ,BAD idea! The B+ Voltage  goes WAY UP more  than 
> the
> original circuit specs ,plus the power transformer receives a SHOCK
> EXCITATION every time the rcvr is turned up thanks to the incoming surge 
> current  ,no
> charge on filter caps so HUGE starting current. Of course one could add a
> surge protection resistor. Slow warm up of the original rectifier tube 
> allows a
> gradual build up of B+ voltage as opposed to the instant turn on of a 
> solid
> state rectifier.
> Nick
>
>
>
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