[R-390] Another (perhaps) silly ballast question

[Barry]

Thanks, Glenn.  I have nice, big, loopy bends in the wire.  I did not know
that about Teflon(tm), though.

Barry - N4BUQ

----- Original Message -----
From: "Glenn Little WB4UIV" <glennmaillist at bellsouth.net>
To: "Barry" <N4BUQ at aol.com>; "R-390 HF Receiver List"
<r-390 at mailman.qth.net>
Sent: Sunday, January 08, 2006 10:09 PM
Subject: Re: [R-390] Another (perhaps) silly ballast question


> Be careful with the Teflon insulation. Make sure that you do not put
> constant pressure on it, either from a very tight bend or pressing it
> between two pieces of metal. Teflon will "cold flow" away from the point
of
> pressure. It will leave a bare spot at the point of pressure. This was a
> common failure with a computer that I serviced for the military. They
> shifted from Teflon to Kynar insulation for this reason.
>
> YMMV
>
> 73
> Glenn
> WB4UIV
>
> At 11:05 PM 01/08/06, Barry wrote:
> >I got part of this mod finished this evening.  I ran a teflon-insulated,
> >20GA wire neatly from the IF deck plug to pin 5 of the ballast tube
socket.
> >At first I thought this wasn't going to work because the compartments are
> >completely isolated from each other between where the plug is located and
> >the tube base; however, there is a very tiny opening where the sheet
metal
> >was folded in just the right way to allow the wire to snake very neatly
> >beside the AGC amp and AGC detectors, beside the BFO and on to the tube
> >socket.  I ran the wire from the center tap through the plug on the IF
deck
> >(even was able to snake the new wire inside the large boot where the rest
of
> >the wires go into the plug and inserted a jumper between pins 5 and 7.  I
> >works great.
> >
> >All I need to do is run the new wire through the plug on the PS.  Kind of
a
> >pain when a resistor or appropriate tube will work, but I really wanted
to
> >do away with the unnecessary heat source.
> >
> >Regards,
> >
> >Barry - N4BUQ
> >
> >----- Original Message -----
> >From: "Barry" <n4buq at aol.com>
> >To: "R-390 HF Receiver List" <r-390 at mailman.qth.net>
> >Sent: Wednesday, January 04, 2006 3:13 PM
> >Subject: Re: [R-390] Another (perhaps) silly ballast question
> >
> >
> > > Well, I was going to wait until I tried it to make sure there weren't
any
> > > "gotchas", but it appears someone else (Dan?) has mentioned this
recently.
> > >
> > > I kept trying to think of a clever way to get 12.6VAC to the
oscillator
> > > tubes -- even to the point of adding a filament transformer somewhere
(it
> > > would be cheaper than a ballast tube costs these days and last
longer) --
> > > when it occurred to me that if the 26.2VAC winding were center-tapped,
> >that
> > > voltage could be used.  That's when I looked at the schematic (and
> >confirmed
> > > on the unit) that the 26.2VAC winding is indeed center-tapped.  This
tap
> >can
> > > be run through unused pins from the PS deck to the IF deck.  From the
IF
> > > deck plug, I plan to run the wire to an unused pin on the ballast tube
> > > socket and plug in a jumper from that pin to pin 7.  This allows the
> > > original oscillator tubes to be used and if someone decides they want
to
> >use
> > > a ballast tube, all that will be necessary is to unplug the jumper and
> >plug
> > > in the ballast tube.
> > >
> > > Barry - N4BUQ
> > >
> > >
> > > > Oh?  Well TELL us what the plan is!
> > > >
> > > > Roy
> > > >
> > > >
> > > >
> > > > - Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
> > > > 7130 Panorama Drive, Derwood MD 20855
> > > > Home: 301-330-8828 Cell 301-928-7794
> > > > Work: Voice: 301-975-3254,  Fax: 301-948-6213
> > > > roy.morgan at nist.gov --
> > >
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