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City: Elko,MN.
Picked up a nice Grunow 835 console a couple weeks ago.
Gentleman I bought it from re-capped it.
It works strong on the AM band from 80 to the top of the dial.
From 55 to 80 I receive nothing.
So far I have not tried the shortwave bands at night, but during the day I am not picking up anything.
Fins on the tuning condensor look fine. Don't see any rubbing.
Any ideas?
Hopefully the coils are all good.
This radio has been re-finished and looks real nice.
The best part is the big colorful dial. Has rich tone too.
murf
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Murf, even if the tuning condenser looks good, I would disconnect it and check for a short with an ohm meter.
Steve
M R Radios C M Tubes
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I have no sch for your model. Anyway.
To add to the above, poor reception on SW may sometimes stem from the fact that the first RF amp stage does nothing and you receive good AM stations using your second stage (detector-oscilaltor, for instrance) as an antenna. If this is the case, if you pull the first tube you will see that the reception did not change and the radio still plays.
This may show to the open RF output transformer for this first stage.
So, if you don't see any shorts etc, try to see the integrity of that coil.
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I have run into this problem before on an AC/DC radio. In my case it was a 22,000 ohm resistor on the 12SA7 converter tube, it would not oscillate on the lower frequency end of the broadcast band. It may or may not be the problem on the Grunow but it's worth checking, even if it has a separate oscillator tube.
Regards
Arran
(This post was last modified: 10-27-2012, 08:50 PM by
Arran.)
Posts: 669
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City: Elko,MN.
Hello fella's,
Well I tried the grunow on shortwave last night and it seemed to be working on all frequencies.
I was able to pull in some stations on am at the lower end of the dial, but they were not as loud and stong as on the upper half.
I found that there was a wire connecting the 2nd and 3rd gangs of the tuning condensor on the terminals on the top.
Wire was frayed and touching the condensor. One end of the wire was just pushed through the hole in the connector while the other end was soldered.
I removed the wire and tried it and it seemed to work better.
I will have to refer to the schenmatic and see if that wire is supposed to be there.
Not sure on how to check the condensor with an ohm meter?
Would you check the stationary fins to the hinged fins or what?
Anyway, have to go out and clean up leaves, so have a great weekend guy's.
murf
Posts: 669
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City: Elko,MN.
Found that wire on the schematics.
Ir is called a capacity coupling.
Works better with it off.
If I connect these with a piece of wire it is dead.
No coupling it seems to work better.
Would this be replaced with a cap or resistor, or should I leave it off?
murf
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May be gimmick capacitor, best left alone, but better informed people may respond with more clarity.
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