[R-390] 1.0 and 0.1 filter settings

[John KA1XC]

Barry,
I'd recommend removing the cover from the L503 coil, and pull the 455 KC
crystal out of its socket and give the pins a cleaning and De-oxit
treatment.

John



> Dan,
>
> Thanks for the reply.  I see what you're talking about now.  I didn't
> realize the cap's job is to "bypass" the crystal, but okay on that.
>
> The problem seems to have fixed itself somewhat.  I'm in the process of
> recapping the IF deck.  I'm replacing a few caps at a time and testing
> between each "session" to make sure I haven't toasted anything.  If it
stops
> working, I'll be able to narrow down where I may have botched something.
I
> replaced the two cathode bypass caps last night and DeOxited the bandwidth
> switch contacts.  The last test seemed to be a lot better than the first
> one.  The signal doesn't drop nearly as much as before.
>
> I washed the deck thoroughly Saturday afternoon and thought I had it dried
> out pretty good, but perhaps there was still a bit of moisture hiding in
> critical places and that may have dried out better overnight.  Perhaps the
> cathode bypass caps in the first IF amp were leaky.  Not sure what
improved
> it, but it appears to be working now.
>
> Six paper caps down in the IF deck and nine more to go.  I'm sure glad
this
> is my hobby!  Some of these are a real pain to replace!
>
> Thanks,
>
> Barry - N4BUQ
>
> ----- Original Message ----- 
> From: "Dan Merz" <djmerz at 3-cities.com>
> To: "'Barry'" <N4BUQ at aol.com>; <r-390 at mailman.qth.net>
> Sent: Sunday, April 10, 2005 2:57 PM
> Subject: RE: [R-390] 1.0 and 0.1 filter settings
>
>
> > Barry,  the crystal may appear to always be in the circuit but it is
> > bypassed by C501 when the switch is in the 2,4,8,16 positions.  The
> crystal
> > filter is effective only in the 1 and .1 positions.  Apparently
something
> is
> > not adjusted correctly in the crystal filter or the crystal is
defective,
> > which is causing the filter to reduce the gain considerably.  I don't
> recall
> > messing with the crystal filter neutralizing in my 390a which is covered
> in
> > the Y2K manual; others may have words of wisdom about problems that
arise
> in
> > the crystal filter circuit,  Dan.
> >
> > -----Original Message-----
> > From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]
> > On Behalf Of Barry
> > Sent: Sunday, April 10, 2005 12:01 PM
> > To: r-390 at mailman.qth.net
> > Subject: [R-390] 1.0 and 0.1 filter settings
> >
> > Can someone give me the "Reader's Digest" version of how these two
> settings
> > work in an R390A?  I'm working on restoring the modules for my newest
> > project.  After replacing C553 (just to be safe), I plugged it in place
of
> > the IF deck in my working R390A.
> >
> > It seems all four filters are working; however, when I switch to 1.0 or
> 0.1,
> > the signal disappears almost completely, no matter how closely I tune to
> the
> > frequency.  I can see that the crystal and its parallel adjustable
> capacitor
> > are always in the circuit, but going to 1.0 switches out the extra cap
and
> > switching to the 0.1 position adds some extra circuitry into the mix.
> >
> > I don't quite understand how these other two settings do their job.  If
> > someone could elaborate, I'd appreciate it.
> >
> > Thanks,
> >
> > Barry - N4BUQ
> >
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