[R-390] R-390 (NON A)

[Dan Merz]

Pat,  I'm unsure from your comment what you are observing and with which
polarity.  It sounds like you reversed (or previously reversed) the polarity
of the meter and now (or before) strong signals make the meter needle go
upscale as it should.  But you say the meter pegs at the zero side and never
moves from there.  Did you try zeroing the meter with the pot on the i.f.
chassis at this time?  If the polarity is indeed correct and the meter is
pegging to the left near 0 then you need to adjust the zero pot on the i.f.
chassis to bring the needle to zero with no signal.  It may be so far out of
adjustment toward the zero side that no signal can bring it back up scale.
Once the meter is zero'd correctly and the polarity is correct,  a signal
should drive the needle to the right

I take it that your other 390 operates normally as far as signals driving
the meter upscale and even though the 390 in question drives the needle in a
backwards direction,  the db points coincide.  This is pure chance.  If you
have the meter polarity reversed and zero the meter with no signal,  then a
signal will drive the meter offscale to the left.    If you reverse the
meter connections under these conditions,  the meter should stay zero'd (or
approximately so) and now the signal will drive the needle upscale.

My conclusion is:  no matter how you have the meter connected,  zero the
meter with the pot on the i.f. chassis.   After zeroing, the needle should
go upscale with a signal.  If it doesn't,  reverse the meter connections.
Now the meter should still be approximately zero'd and the needle should go
the right direction upscale with a signal.  You may have to re-zero the
meter a bit.  Dan.  

-----Original Message-----
From: Patrick [mailto:brookbank at triad.rr.com] 
Sent: Thursday, June 02, 2005 8:03 AM
To: Dan Merz; r-390 at mailman.qth.net
Subject: Re: [R-390] R-390 (NON A)

Dan, I did reverse the leads and the meter pegs on the 0 side and never
moves from there. So, at least for now I think the polarity is OK. The
strange part is that since I have two R-390, when I tune them both to the
same station, both meters settle at about the same  DB level, both using
very similar antennas.
So it just does not bother me to much from a operational point of view, but
it does from a purist perspective.

If you have any other ideas, please let me know. I have the alignement
procedures here at home, but do not have the wiring diagrams to try to make
sense of this problem.

Thanks ........Pat
----- Original Message -----
----- Original Message -----
From: "Dan Merz" <djmerz at 3-cities.com>
To: "'Patrick'" <brookbank at triad.rr.com>; <r-390 at mailman.qth.net>
Sent: Thursday, June 02, 2005 2:41 AM
Subject: RE: [R-390] R-390 (NON A)


> Pat,  the thing that comes to mind is that you have the leads to the 
> meter reversed.  I looked at my meter and this would be easy to do.  I  
> assume if you zero the meter at zero then when a signal appears it 
> goes downscale and
> off the scale,   and hence you have to zero it toward the high end of the
> scale to get signal response the way you described.  My leads are 
> color coded but I don't know if the color code is universal to all 
> 390's.  But you could trace the leads with an ohmmeter back to the 6th 
> i.f. tube/agc tube to see which is which.  The minus side should go to 
> the agc tube,  the plus side to the 6th i.f. tube. Disconnect the two 
> meter leads and pull the two tubes and measure from the cathode pin of 
> each tube to the two leads to see which is which (power off on the set 
> !!) Or just reverse the leads and see if it works ok then.  Email me 
> if you need more info on which tubes I'm talking about.  Dan.
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net 
> [mailto:r-390-bounces at mailman.qth.net]
> On Behalf Of Patrick
> Sent: Wednesday, June 01, 2005 3:08 PM
> To: r-390 at mailman.qth.net
> Subject: [R-390] R-390 (NON A)
>
> Have a r-390 that have just finished working on it, replaced defective 
> PTO, Crystal calibrator, checked all tubes and replaced some weak 
> ones, then aligned it. It work great, But the carrier lever meter 
> works backwards, the stronger the signal, the less the indication on 
> the meter. Have replaced the meter and there is no change.
> Can someone put me on the right track for this problem?
>
> Thanks in advance for any and all suggestions,
>
> Pat
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