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 Post subject: RCA 811K : noise when using automatic tuning
PostPosted: Jan Thu 12, 2017 4:34 pm 
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Joined: Apr Sun 30, 2006 2:28 pm
Posts: 24
Location: Rhode Island, USA
The radio is working well. Electrolytic and paper capacitors are replaced and so are wires with crumbling insulation. My problem is with the automatic tuning mechanism.

I got the tuning working so that in automatic mode the push of a station button causes the dial to search out and stop on the station. The receive suppression switches are adjusted so that the motor armature pulls back in after the station is found and sound returns to the radio. I also have the direction change switch working so that when the end of the dial is reached the mechanism reverses direction.

My problem is with the noise of the gears. When the dial is travelling from right to left it makes a racket and moves slowly. When it moves from left to right it moves quickly and with almost no sound. Might anyone be able to pinpoint the fix for this? Is it a backlash adjustment of gears at the bottom of the stack of gears? Thanks!

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 Post subject: Re: RCA 811K : noise when using automatic tuning
PostPosted: Jan Thu 12, 2017 4:44 pm 
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Joined: Aug Tue 13, 2013 3:18 am
Posts: 1073
Location: Milwaukee, Wisconsin
There are notes here for adjusting a couple things in the geartrain.

http://oldtech.net/RCA/811K-p9.gif

And here are the corresponding drawings of the mechanism and parts.

http://oldtech.net/RCA/811K-p8.gif

My 811k operates at about the same speed and noise level in both directions. So maybe going through the listed adjustments you'll have some luck.


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 Post subject: Re: RCA 811K : noise when using automatic tuning
PostPosted: Jan Thu 12, 2017 7:27 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 5213
Location: Near Brandon, Iowa
Sound level won't ever be zero but should be more or less equal in both directions; at least, mine is. Has the gear train been cleaned and lubed? There are lots of moving parts in this mechanism, including the dial cord pulleys, which may have acquired some "directionality" due to dust or hardened grease accretions.


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 Post subject: Re: RCA 811K : noise when using automatic tuning
PostPosted: Jan Thu 12, 2017 8:05 pm 
New Member

Joined: Apr Sun 30, 2006 2:28 pm
Posts: 24
Location: Rhode Island, USA
I do have the references mentioned above and have used them to get things working. The part about noise is a bit confusing.
The only part I lubricated so far is the sliding track under the dial pointer. I will put some machine oil on the gears and bearing points to see how that works. Or should I stick with the Vaseline that I used on the dial track?
I agree there will always be noise. I should have said that moving right to left it is not loud and nasty sounding like in the other direction.
Thanks to you both for the suggestions!

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Ken Carr - KE1RI - Wordpress Blog: http://www.idlenot.com


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 Post subject: Re: RCA 811K : noise when using automatic tuning
PostPosted: Jan Fri 13, 2017 1:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1830
Location: Lafayette, CO
I've had one or two of those RCA's with that setup. Those are their nicer ones. You might try to mimic the motor drive and twist it in your fingers. You'll get a feel for what load that 24-volt motor is seeing. Could be a motor bearing, probably some alignment. I believe the cable for the dial needle is a copper cable: tough but doesn't like kinks. If the gears are worn, they are going to make noise, just might have badly worn only in one direction. Fun radio to work on....good luck, Craig


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