[NJARC] BC-348

[John Ruccolo]

Hi Jim,

Scott's BC-348 was in a B-24 that got hit in a raid over Frankfurt, and hasn't been the same since. It's been humming since 1944.

JR


--- On Tue, 11/4/08, Jim Whartenby <antqradio at sbcglobal.net> wrote:

> From: Jim Whartenby <antqradio at sbcglobal.net>
> Subject: Re: [NJARC] BC-348
> To: njarc at mailman.qth.net
> Date: Tuesday, November 4, 2008, 7:51 AM
> Visit our web site - See http://www.njarc.org
> _______________________________________________
> Scott
> Hum is there regardless of volume control setting?
> Does the radio otherwise receive?
> Are the tube filaments also powered by the DC supply?
> Was the big capacitor under the dynamotor tested or
> replaced?
> Jim
> 
> 
> --- On Tue, 11/4/08, Scott Roberts
> <ng19delta at yahoo.com> wrote:
> 
> > From: Scott Roberts <ng19delta at yahoo.com>
> > Subject: Re: [NJARC] BC-348
> > To: "NJARC Radio Club"
> <njarc at mailman.qth.net>
> > Date: Tuesday, November 4, 2008, 1:17 AM
> > Visit our web site - See http://www.njarc.org
> > _______________________________________________
> > Well, I haven't had any replies yet...
> > 
> > I added a pair of filter caps and a choke to thw 28VDC
> > power supply I cobbled together, but no change in the
> hum.
> > So, I am going to replace the caps in the dynamotor
> and see
> > what that does. After that, ? I guess I just start
> fiddlin
> > with stuff.
> > 
> > Any help still appreciated!
> > Thanks!
> > Scott
> > 
> > 
> > --- On Mon, 11/3/08, Scott Roberts
> > <ng19delta at yahoo.com> wrote:
> > 
> > > From: Scott Roberts <ng19delta at yahoo.com>
> > > Subject: [NJARC] BC-348
> > > To: "NJARC Radio Club"
> > <njarc at mailman.qth.net>
> > > Date: Monday, November 3, 2008, 2:24 PM
> > > Visit our web site - See http://www.njarc.org
> > > _______________________________________________
> > > Hi Everybody-
> > > I am messing about with my BC-348P(Not my
> Uncle's,
> > but
> > > the one I picked up at the swap meet a few months
> > back) and
> > > am setting it up for its original power supply.
> Dave
> > Sica
> > > did me a great favor, and swapped me a BC-348
> > dynamotor and
> > > mount in exchange for a radio I had he was
> interested
> > in. I
> > > cleaned & relubricated the bearings on the
> > dynamotor,
> > > and put it into the de-modified chassis after
> testing.
> > My
> > > test rig is simply a 25.2 VAC transformer,
> rectified
> > through
> > > 4 1N4007 diodes, but no filter caps. (This tuning
> > units, see
> > > nothing may be important...)
> > > 
> > > The dynamotor tested out nicely- on 25.2
> > VDC(rectified) it
> > > was putting out around 230 VDC. The few caps in
> the
> > > dynamotor are original, one a nice metal one, the
> > other a
> > > paper cap. (It is a DM-28-Q, from a BC-348-Q)
> Caps
> > have not
> > > been replaced in the dynamotor, but all caps were
> > redone in
> > > the BC-348-P.
> > > 
> > > When I switch the unit on, in either AVC or MVC
> mode,
> > with
> > > the proper impedence headset, or speaker, I get a
> hum,
> > but
> > > no indication of volume control- no scratchiness,
> > nothing,
> > > but a hum. I have tried running it through the
> FL-30-M
> > > filter(similar to FL-8-A) but it has no effect.
> Could
> > this
> > > be a hum from my cheap-a** power unit(literally
> thrown
> > > together to form a circuit) that could be solved
> by a
> > couple
> > > filter caps before it comes into the radio?(If
> so,
> > would
> > > 47/450Es be about right?)
> > > 
> > > I have been rechecking my wiring repairs, and,
> other
> > than
> > > tearing out the tuning units and looking into
> them I
> > see
> > > nothing obviously missed. Tubes have all been
> tested
> > on my
> > > Precision tester, and check out fine.
> > > 
> > > Ideas?
> > > 
> > > Thanks!
> > > Scott
> > > 
> > > _______________________________________________
> > > NJARC mailing list
> > > NJARC at mailman.qth.net
> > > http://mailman.qth.net/mailman/listinfo/njarc
> > _______________________________________________
> > NJARC mailing list
> > NJARC at mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/njarc
> 
> _______________________________________________
> NJARC mailing list
> NJARC at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/njarc