[NJARC] Philco 42-321

[john ruccolo]

Hi again Ed,

I took a look at the schematic, and I do *not* think
this is a hot-chassis receiver. To my knowledge,
Philco did it the *right* way and used a floating B-
bus (unlike Emerson, Fada, and others).

Still, the set could have been modified by someone
not-so-knowledgeable -- a good rule of thumb with ALL
AC-DC (power transformer-less) sets is to *always* use
an isolation transformer when working on them.

Regards,

John


--- Edward Otte <edotte at optonline.net> wrote:

> Visit our web site - See http://www.njarc.org
> _______________________________________________
> 
> 
> Jim,
> 
> I am not sure I fully understand. I just started
> taken note of the schematic
> and it dawned on me. Depending on how I hook the AC
> plug into the socket the
> chassis will either be ground/ neutral 0 volts or
> 120 Volts hot! Yikes! So
> the -B supply goes there too. 
> 
> But I agree with you how many Henry's could there be
> in a wire twisted six
> or seven times around a 1/2 inch capacitor. 
> 
> Edward
> 
> Edward
> This is an AC/DC set and it predates polarized
> plugs.  So it looks like
> it is a series LC circuit used to connect the B-
> power supply terminal
> to the chassis.
> 
> It would be nice to know the inductance so we could
> calculate the
> resonant frequency.  Need to know how many turns of
> wire and what is
> the cross section of the capacitor? And then there
> is the matter of Q.
> 
> I don't think Philco used this circuit for long.  I
> don't remember
> seeing this in a late 40s AC/DC set I reworked that
> had AM and both the
> old and new FM bands.  My gut feeling is that this
> inductor is not at
> all critical and can be deleted when you replace the
> old wax coated
> ones with modern capacitors.
> Regards,
> Jim
> 
> --- Edward Otte <edotte at optonline.net> wrote:
> 
> > Visit our web site - See http://www.njarc.org
> > _______________________________________________
> > 
> > Hello all,
> > 
> > I have a general question about the Philco 42-321.
> There is a
> > "condenser &
> > choke assembly" which consists of a 0.2 uF
> capacitor with a number of
> > wires
> > wrapped around it. There is a Philco part number
> but what if I wanted
> > to
> > replace it? The coil portion is just a wire and it
> has a certain
> > radius
> > would I have to recreate this or is there an easy
> solution? Thanks in
> > advance.
> > 
> > Edward
> > 
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> > http://mailman.qth.net/mailman/listinfo/njarc
> > 
> 
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