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 Post subject: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sat 23, 2020 7:09 pm 
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Location: Miami, FL
I'm restoring an RCA Victor Model 9-Y-510 radio/45 phonograph combo. It has a coil antenna but it's not pulling in any stations. It only works if I attach a wire antenna to the coil. What could be the problem?


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sat 23, 2020 7:54 pm 
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Location: San Jose, CA USA
The first thing to check is whether both wires from the antenna loop are properly connected to the chassis. If one is broken or disconnected, one might expect about what you're seeing.

Otherwise, the radio could simply be very weak on sensitivity right now for a variety of reasons. How much restoration work has been done on this previously? For example, have the electrolytic and paper capacitors already been replaced?

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Tom K6VL


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sat 23, 2020 8:09 pm 
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Joined: Sep Thu 11, 2008 4:43 pm
Posts: 343
Location: Miami, FL
The antenna is properly connected and all the capacitors have been replaced.


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sat 23, 2020 8:51 pm 
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Let's check to see if the resonant circuits of the radio are operating properly. Any resonant circuit that's malfunctioning will tend to kill sensitivity.

Tune in a weak station (using an external antenna if can't get any reception without) and try adjusting the top and bottom adjustments on both IF transformers. Do you get a clear peak on each one, without having to turn very far from the original position? If one or more doesn't have a clear peak in signal strength, that tells us that that particular tuned circuit has a problem.

Likewise, try adjusting the antenna trimmer capacitor on the tuning capacitor. It will be the trimmer attached to the larger of the two gangs. Does it have a clear peak within its adjustment range? If the signal strength is max with the antenna trimmer either all the way tight or all the way loose, that's an indication of a problem in the front end. This adjustment will be much more sensitive on a station near the top of the dial than on one near the bottom, so best to choose a station near the top of the dial if you can get one.

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Tom K6VL


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sat 23, 2020 10:08 pm 
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Joined: Sep Thu 11, 2008 4:43 pm
Posts: 343
Location: Miami, FL
Both IF transformers test fine with the top and bottom adjustments. With the antenna trimmer there is no reception when it's completely tight and louder as I loosen it.

Thanks for your help.


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sat 23, 2020 10:15 pm 
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Location: San Jose, CA USA
Two possibilities to check first:

1. Antenna coil is actually not wired in properly, or has a broken wire. Test its continuity with an ohmmeter.

2. Oscillator trimmer is too loose. Try tightening the oscillator trimmer (the other one on the tuning capacitor -- the one on the smaller gang). This will move stations up the dial a little. Then check antenna trimmer again at top of dial. Does it peak within its range, or does it still work best with it all the way loose? If so, repeat one more time, tightening the oscillator trimmer all the way tight. Antenna trimmer still works best all the way loose?

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Tom K6VL


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sun 24, 2020 2:15 pm 
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Joined: Sep Thu 11, 2008 4:43 pm
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Location: Miami, FL
There's no reception with the oscillator trimmer tight all the way. It works best almost tight. The antenna trimmer doesn't work best all the way loose. It also works best almost tight. The antenna test fine and there are no broken wires.


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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Sun 24, 2020 3:18 pm 
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Location: San Jose, CA USA
A couple more things:

Have the tubes been tested?

Audio amplifier test: if you turn the volume up half way, and then touch a piece of wire a few feet long on the center terminal of the volume control, do you get a fairly loud hum in the speaker?

What you’re reporting for the behavior of the antenna trimmer sounds problematic, but we’ll focus on other things for now and come back to that later after other causes eliminated.

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 Post subject: Re: RCA Victor Model 9-Y-510 Antenna Problem
PostPosted: May Mon 25, 2020 4:44 pm 
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Joined: Sep Thu 11, 2008 4:43 pm
Posts: 343
Location: Miami, FL
The tubes have been tested. There is a slight hum at the center terminal, not loud. I do have two stations coming in. I sent you a PM.

Thanks,


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