Grunow 1191 restoration
 

While I've been waiting for the finish to dry on my Motorola 12K2, I took a stab at getting this Grunow 1191 running. It has an 11G chassis

I got it cheap because of the nasty water damage at the bottom. i was going to part it out, but it's in such nice shape aside from the bottom I guess I'll try restoring it.

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Yikes! It sat in about a foot of water :tears:
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At least I can clean it up a with a little GoJo for now.
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I first checked the tubes and discovered two metal types. I replaced those with glass ones. It also came with a neat ST type 6H6.

All the tubes tested quite good including the eye and 6F6 output tubes. Every single tube is a different brand except the two 6F6s :o

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Someone has worked on this set before. Some of the replacements caps are the wrong value and these dogbones are not the correct wattage.
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I found one nicely roasted paper cap.
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Here it is recapped and with new power resistors. I'll restuff the cans once I get it working.
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I powered it up with a dim bulb and all seemed OK. Very scratchy while tuning though and the volume is a little weak. It looks pretty though :)

I'm thinking maybe the tuning cap plates are shorting out, but I don't see any obvious rubbing :scratch2:
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Cool looking radio. At least the water didn't get into the voice coil. Looks like the speaker will survive.

Yep, the speaker is still good :) I'm just a sucker for beat up sets that no one else wants.

I'm getting a 1930's Zenith set for free. Have not had a chance to pick it up yet. Looks about the same on the bottom as yours. It's also missing a dial glass. :(

I think you can get reproduction dial glass.

If I had the means, I'd fabricate some new hardwood frame pieces. Instead, I'll see if I can stabilize and salvage them. They're still solid, just cracked an warped.
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The veneer isn't so bad because the big side sheet are OK. I figure I'll replace the bottom strip and some around the speaker grille.
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That's going to be a great radio when done. The scratchiness might not be plates rubbing but dirty electrical contact between the frame and the rotor.

Bingo! A little fine sandpaper and deoxit on the frame/rotor contacts solved that problem :thmbsp:

As for the weak gain, I found an open secondary on this RF transformer. Thankfully, that's the coil with only a few turns

I'm amazed at how many stations I can pick up with essentially no antenna other than the grid cap lead on the RF tube.

I'll carefully unwind it and note the direction and number of turns then rewind it.

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The radio came with a crude tuning belt made from twine.
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It should be a rubber belt like this.

I did a web search and came across Adam's Radio website that sells many belts including this set. I've never heard of this site before - anyone familiar with them ?

http://www.adamsradio.com/page7.html

12 new turns counter-clockwise when viewed from the bottom did the trick :)
Also, batterymaker suggested I check the resistor inside the eye tube socket. I cracked it open and indeed it was 50% high! It's much more responsive now.
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Love that tuning cord! Strange things found inside radios...

While working on the cabinet, I found the original dial belt. It's hard as a rock
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The frame has seen better days, but the pieces are sound.
I'm going to glue, clamp and screw them back together as best I can.
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Impressive work thus far! I bet that cabinet turns out great. The big Grunow consoles are nice. Great looking dial. And sensitive since you were getting reception with that open coil. On that label on the rear of the chassis, and on other Grunow sets that have the same label with that signature, is it Wm. C or O Grunow? Anyone know? Have seen those labels many times and have never known for sure.

Gilbert