[R-390] Best ballast tube resistor

Mon, 12 May 2003 23:10:48 -0700 (PDT)

Put a fixed reistor in the chain, so when the pot is at ZERO you still have the "40 Ohms" in
series with the fillament.

Rodney
VK2KTZ

--- Jim Miller <[email protected]> wrote:
> I drilled a 1/4 inch hole in my front panel to the right of the VU meter and
> installed a 15W wirewound pot.  I am able to adjust the pot for optimum
> operation of the oscillator tubes.  Since the changing filament voltage does
> cause a slight frequency shift, this can also double as a vernier tuning
> capability.  I am now working on calibrating the dial in Hz offset.  You
> must be very careful to avoid turning the pot to zero however, as it will
> fry the oscillator tube filaments.  I am thinking of using a sheet metal
> screw as a safety stop for this purpose.
> 
> ----- Original Message -----
> From: <[email protected]>
> To: <[email protected]>
> Sent: Monday, May 12, 2003 9:29 PM
> Subject: [R-390] Best ballast tube resistor
> 
> 
> > Should I use a 39 or 40 ohm resistor to replace my bad ballast tube?
> >
> > 1%, 5% or 10% and what wattage?
> >
> > Someone told me that if I use a resistor, my R-390A would not work
> properly.
> >
> > What should I do?
> >
> >
> >
> > The Firebottle
> > The Original
> > Accept No Substitutes
> >
> >
> >
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> 
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