RCA X551 Humming

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Re: RCA X551 Humming

Post by 75X11 on Thu Sep 11, 2014 10:12 pm

Thanks. It's the one shown in alignment step 4. to be adjusted using a 1400 khz signal.
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Re: RCA X551 Humming

Post by jerryhawthorne on Fri Sep 12, 2014 12:08 am

Frank, the fact that other tube radios you have do not have the problem I would not spend time on "power line" problems or speculating where the problem is coming from until you use your signal generator to move it along. It will simulate a radio station you can inject and see when it starts to fade. Start with the first grid on the IF with a modulated signal and see if does the same thing. I have no experience with your particular radio and perhaps many have that would provide you with their common failures. Nothing beats a systematic approach to repairing radios and it goes from amplifier forward toward the IF and then antenna. You have the stuff to do it and determine which area the problem is in.
Of course it great to check solder connections. But nice to figure out where to look as there are a lot of them.

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Re: RCA X551 Humming

Post by frank1956 on Fri Sep 12, 2014 11:28 am

I am going to attempt an alignment on this radio. After reading a few article on vintage radio's it is probably wise to do so. I am just a little puzzled after looking over the schematics for this radio. It states and I quote.

Test-Oscillator-- For all alignment operations, connect the low side of the test-oscillator to the receiver chassis, and keep the oscillator output as low as possible to avoid a-v-c action.

I understand and know what the low side of the generator is and how to keep the output as low as possible, what is a little confusing to me is the low side connectivity. Is is just to the chassis any were, or is it to the  chassis ground as indicated on the schematic (the little rack looking symbol) It not very clear to me. Thanks

Frank
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Re: RCA X551 Humming

Post by Wildcat445 on Fri Sep 12, 2014 11:38 am

Chassis is chassis, Frank. That little rake symbol indicates chassis connection. You can connect the low side of the generator to any convenient location on the chassis. Good luck.

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Re: RCA X551 Humming

Post by frank1956 on Fri Sep 12, 2014 12:31 pm

WC, Thanks. One more question before I began. Step 2 says Stator of C1-2 through .01 mfd.

Got the high side of the generator and the .01 mfd, where is C1-2 located on the radio. I see it on the schematic (C1-2 10.3-598 it looks like) and have traced it down to 12BE6 pin 7 after that I am lost??? Sorry for all the question.

The rest of the alignment I should have no problems with (I hope lol! )
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Re: RCA X551 Humming

Post by 75X11 on Sat Sep 13, 2014 1:04 am

I would connect it to the fixed frame of your tuning capacitor, with maybe an alligator clip.
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Re: RCA X551 Humming

Post by Wildcat445 on Sat Sep 13, 2014 1:57 am

75 is right. If you look on your schematic, at the top of the page, there is a drawing of the radio chassis, showing tube locations, etc. Look in the middle at the tuning capacitor. You will see "C-1 ANT." and "C-2 OSC." Those connections are the C-1 and C-2 the alignment instructions are referring to. There should be a wire going down into the chassis on those connections. The oscillator connection should eventually end up on the grid terminal of the 12BE6, you are right about that. These instructions are asking you to tune each IF transformer seperately, just like you were doing with your Silvertone. I hope this answered your question. If not, please feel free to ask until you understand what you need to do. Good luck.

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Re: RCA X551 Humming

Post by frank1956 on Sat Sep 13, 2014 12:50 pm

WC, 75X11 Thanks for the advice. I see exactly were it goes. Since this is my first alignment and really the very first time to use my signal generator for this type of procedure.

I have been trying to find online something to show how to read the dial on the generator. I get the 455kc, 600kc etc. What I don't get is  confused when it says to set the generator to 1620kc. On the eico 324 band B goes from 400kc to 1.2mc, so where in between is such settings as 1400kc, 1620kc etc. Is there something I can get fro a reference from here on out?

Frank
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Re: RCA X551 Humming

Post by 75X11 on Sat Sep 13, 2014 1:50 pm

1400 Kc is 1.4 Mc. 1620Kc is 1.620 Mc.  If you can access the instructions for your oscillator, you can see if it will create a harmonic at those frequencies.  An oscillator usually generates harmonics that are extra signals that are like ripples that form on each side of the center frequency.  You may be able to find one by using a known good radio tuned to each of those frequencies, and tuning your oscillator so the radio would recieve it.  That is a dirty way to do it without a frequency counter or spectrum analyzer.  It should quiet if you have no tone on the signal or get the tone if you have one injected on the RF.  Just lay your output line near the radio or antenna.
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Re: RCA X551 Humming

Post by frank1956 on Sat Sep 13, 2014 2:22 pm

75, Thanks. I need to go up one band width. Band C cover what I need in order to do this alignment. I really appreciate this. I have started me a TRF radio DIY book, so next time I can just refer back if that subject was covered.

Frank
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Re: RCA X551 Humming

Post by Bill Cahill on Sat Sep 13, 2014 2:50 pm

What about your intermittent hissing? Did you fix that?? Aligning won't likely fix that problem. Fix that problem first. Most of my AM radios after restoration, don't need much more than a minor touch up.

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Re: RCA X551 Humming

Post by frank1956 on Sat Sep 13, 2014 3:07 pm

Billy, as far as I can tell the intermittent problem has been fixed. Re checked solder joint and corrected any problems. Radio ran for 2 hours the other night with no problem except stations not coming in clear. That is way the alignment.

Frank
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Re: RCA X551 Humming

Post by Bill Cahill on Sat Sep 13, 2014 3:24 pm

Please call me Bill

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Re: RCA X551 Humming

Post by 75X11 on Sat Sep 13, 2014 3:46 pm

That's good. The way you had put it, I thought the band you mentioned originally was the highest and some contingencies were in order. Good Luck!
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Re: RCA X551 Humming

Post by frank1956 on Sat Sep 13, 2014 4:40 pm

Bill Cahill wrote:Please call me Bill

Sorry fat fingers.
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Re: RCA X551 Humming

Post by frank1956 on Sat Sep 13, 2014 4:44 pm

The only problem I can see, is in the day stations are slightly weaker then night. Volume is lower even at max output in the day except when attenta board is touched or held then volume is louder at max output as the other tube radio's I have.

Frank
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Re: RCA X551 Humming

Post by Wildcat445 on Sat Sep 13, 2014 5:01 pm

Your alignment may not be perfect. What you are experiencing is pretty much normal. No harm will be done leaving it like that.

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Re: RCA X551 Humming

Post by 75X11 on Sat Sep 13, 2014 5:28 pm

You can always return to it as you get more experience.
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Re: RCA X551 Humming

Post by frank1956 on Sun Sep 14, 2014 8:24 pm

I believe the alignment worked and the radio seems to be doing ok. Keeping my finger's crossed. Thanks for the help.

Frank
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Re: RCA X551 Humming

Post by Wildcat445 on Sun Sep 14, 2014 8:45 pm

That's great, Frank! Very Happy

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Re: RCA X551 Humming

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