[NJARC] Hallicrafters SX-16

[John Ruccolo]

Hi again Scott,

Also -- regarding lack of audio output, do resistance checks on the "driver" transformer between the 6R7 and the 6V6's, and also the output transformer. Could be a problem there.

And, the output transformer has taps for 500 and 5000 ohms. You can't use a modern 4 or 8 ohm speaker with that set, at least not without some kind of matching transformer. I assume you already knew that, but just in case....

Good Luck!

JR

--- On Sun, 4/12/09, jr6v6gt at yahoo.com <jr6v6gt at yahoo.com> wrote:

> From: jr6v6gt at yahoo.com <jr6v6gt at yahoo.com>
> Subject: Re: [NJARC] Hallicrafters SX-16
> To: "NJARC Radio Club" <njarc at mailman.qth.net>, "Scott Roberts" <ng19delta at yahoo.com>
> Date: Sunday, April 12, 2009, 10:35 PM
> Just remember 
> Reply = Poster
> Reply All = Everyone
> 
> _________________________________________________________
> 
> Hi Scott,
> 
> Before I comment, one question -- have you reaplaced ALL of
> the filter caps, so you don't fry the power transformer
> again?
> 
> I just looked at the schematic on Nostalgis Air. BFO's are
> pretty simple -- basically, a tuneable 455 Khz osc. Basic
> resistance and voltage checks should find the problem fairly
> quickly and easily. The only thing that might "throw" you is
> if the BFO coil is open -- but a basic ohmmeter test will
> uncover that -- check that first.
> 
> We've been down this road before with your SX-16 -- this is
> not a 5-tube AA. It's a fairly complicated set -- what I
> mean is, it's probably a bit too complex to troubleshoot via
> email. It may need another trip to an NJARC clinic! ;-) I
> have learned the hard way that making troubleshooting
> suggestions via email is a hit-and-miss business at
> best....
> 
> No audio output? Check the plate voitage on the 6V6's. Also
> measure from plate to cathode, to ensure that the cathode
> resistor (235 ohms?) has not opened. Also check screen
> voltage. Also check plate voltage at 6R7 1st audio stage.
> 
> Looks like you've got several problems. Lack of sensitivity
> on the higher-freq bands could be due to a weak osc. tube,
> bandswitch issues, coil/cap issues, etc.
> 
> Do you have a signal tracer? Very handy gadgets -- this
> would be a good set to practice on.
> 
> Regards,
> 
> John
> 
> --- On Sat, 4/11/09, Scott Roberts <ng19delta at yahoo.com>
> wrote:
> 
> > From: Scott Roberts <ng19delta at yahoo.com>
> > Subject: [NJARC] Hallicrafters SX-16
> > To: "NJARC Radio Club" <njarc at mailman.qth.net>
> > Date: Saturday, April 11, 2009, 8:29 PM
> > Just remember 
> > Reply = Poster
> > Reply All = Everyone
> > 
> >
> _________________________________________________________
> > 
> > Hi Guys-
> > Getting back to the SX-16 after waiting for the
> transforer
> > to be rewound. Came back the other day, very nice job
> by TRS
> > in Maine.
> > 
> > Anyway, it seems I still have a couple problems:
> > 1 BFO still does not seem to be operating
> > 2 Amplification seems missing. I do not seem to be
> getting
> > proper amplification- If I connect anything besides
> > headphones, it does not have enough power to get the
> speaker
> > going. If I switch the crystal in, I can hear stuff
> through
> > the headphones, without the crystal, it is minimal.
> Even
> > with the crystal, volume is at full, with minimal
> sound.
> > 
> > And seems like nothing coming through in the top 3
> > bands.(10-61 khz)
> > 
> > Ideas?
> > 
> > Thanks!
> > Scott
> >
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> 
>       
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