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 Grunow 1191

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herromc
Beginning Member


Join date : 2017-08-26

PostSubject: Grunow 1191   November 8th 2017, 10:53 am

Well, I finally got this radio in good working order.  Recently I had a problem with the potentiometer (vol. too loud), turns out it had a cracked taper.  Luckily I had a spare that worked great.
Now I ran across a small problem with the local radio station frequencies being somewhat off.  Below is an example of what I'm talking about, and as I go up the dial they get further apart.
My question is: What might be causing this, and can it be fixed?  I noticed that on the rear of the chassis (outer) there is an small adjustment screw, but I don't know what it's for.  Anyone know?

Frequency   Comes in at   Off


 860           850             -10
1130          1100            -30
1290          1240            -50
1400          1330            -70
1640          1560            -80
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chas
Junior Member 50+ Posts
Junior Member 50+ Posts
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Join date : 2017-04-09

PostSubject: Re: Grunow 1191   November 10th 2017, 7:05 am

The oscillator is not in alignment.

Need an RF generator, output meter and the alignment instructions.

If the radio will not align there may be a drifted component in the oscillator circuit.

All alignment begins with mechanical setting of the dial indicator at some known marker on the dial at the lowest frequency with the tuning condenser closed.

If there are worn/hard rubber mounts on the tuner that cause a mechanical shift in the dial vs tuner these must be stabilized and centered first, then set for the closed position.

The rear adjustment is an "IF rejector"

See: http://antiqueradios.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=157337

Chas
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herromc
Beginning Member


Join date : 2017-08-26

PostSubject: Re: Grunow 1191   November 10th 2017, 7:20 am

Thanks for the help!
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wildcat445
Technician
Technician
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Join date : 2014-08-16

PostSubject: Re: Grunow 1191   August 24th 2018, 3:37 pm

I decided to tune my 1191 up after putting up with lousy performance for 35 years or so.  I did a recap, checked resistors and changed a couple.  The 5Z3 rectifier has been changed to a 5U4 sometime in the past.  They used a wafer octal socket for the rectifier and it is coming apart.  So I need to replace it.  The biggest problem I see is that the small wires (looks like bell wire) that carry B+ to the IF transformers has rubber insulation.  I can see that there is bare wire where the wire runs thru the chassis up to the IF transformer.  What is the easiest method to change these two wires.  It looks to me like I need to unbolt the transformer from the can, then the can from the chassis.  I have a parts chassis if I screw something up.  This started out to be just an alignment and minor stuff and is turning into a restoration project.  No wonder the performance was poor.

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Often in error, seldom in doubt.
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