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 Post subject: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Jun Tue 18, 2019 11:49 pm 
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Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
This radio has a Westinghouse logo on it but it was made by RCA. Circuit diagram is here. http://www.nostalgiaair.org/pagesbymode ... 040311.pdf

All the resistors in this radio are on a "resistor board". Here is a picture of the board.

All the resistors in the radio are on this board and appear to be 1 watt in size except for the one on the left which looks like it is 2 watts. The 2 watt resistor is R4. Do these resistors need to have this wattage?

Thanks, Bob


Attachments:
Westinghouse-RCA R-5AC resistor board (2) - resize.jpg
Westinghouse-RCA R-5AC resistor board (2) - resize.jpg [ 369.01 KiB | Viewed 742 times ]
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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Jun Wed 19, 2019 1:46 am 
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Joined: Nov Tue 14, 2017 5:09 am
Posts: 2017
Location: Austin, Texas
It appears that you have all the information to calculate the resistor wattages.
For instance R2 is 600 ohms and the voltage chart shows 3 volts on the cathode of the tube 1.
The power would be (3 x 3) / 600 = 0.015 watts
R4 is about 1 watt but the others appear to be much less than a watt.

Jay


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Jun Wed 19, 2019 6:59 pm 
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Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Thanks Jay for pointing out the voltages. I think I've got all of the resistors figured out except for R10 and R11. What is the voltage drop across these two?

Thanks, Bob


Last edited by rck46 on Jun Wed 19, 2019 8:52 pm, edited 1 time in total.

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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Jun Wed 19, 2019 8:50 pm 
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Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Another question. I have checked out continuities of all the coils. I find that L3 shows 8 ohms while the circuit diagram indicates it should be 91 ohms although my copy is hard to read. Could it possibly be 9.1 ohms or is the coil shorted and needs to be rewound?

Thanks, Bob


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Jul Tue 16, 2019 12:03 am 
Member

Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
I went through this radio and replaced all the caps and resistors. I replaced C18, the 2 mfd paper cap with a 4.7mfd, 450 volt electrolytic.

I get some reception at the lower end of the dial but nothing at the upper end of the dial unless I touch the grid cap of tube 1. When I do this I get no reception at the lower end of the dial.

I get a good response across the dial when inputing a signal at the antenna lead from my signal generator.

I tried adusting the two trimmers, C3 and C10, at 1400kc but did not improve results.

B+ measures about 230v.

Could the problem lie with L-3 which measures about 8 ohms rather than 91 ohms as shown on the circuit diagram? All other coils ohm out ok.

All tubes test good.

Any suggestions will be appreciated.

Thanks, Bob


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Jul Sun 21, 2019 10:39 pm 
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Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
I am bumping this up with the hope that someone has some ideas on my reception problem. I pulled L3 from the radio. It is on the same coil form as L4, L5, and L6. It is the light colored coil in the following photo. On close inspection I do not see any problems with it. As I mentioned earlier it measures about 8 ohms rather than the 91 ohms indicated on the circuit diagram. The yellow cap you see is C-13.

Bob


Attachments:
Westinghouse (RCA R-5 AC) coils L3, 4, 5, 6 (2),resize.jpg
Westinghouse (RCA R-5 AC) coils L3, 4, 5, 6 (2),resize.jpg [ 343.81 KiB | Viewed 553 times ]
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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Sat 17, 2019 7:14 pm 
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Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Got back to this radio yesterday and determined the following:

a. Coil L3 is ok. I believe the resistance for this coil shown on the circuit diagram should be around 9 ohms rather than what appears to be 91 ohms.

b. Alignment instructions call for adjustment of the two trimmers while the chassis is in the cabinet. This requires a right angle wrench which I don't have. I adjusted the trimmers with the chassis out of the cabinet. Would this make a significant difference in reception?

c. The chassis needs to be grounded to get decent reception at the upper end of the dial. If not grounded there is no reception at the upper end of the dial.

d. I can barely hear a strong local station at the lower end of the dial. Removal of the ground makes no difference.

I am using a 25 foot long antenna strung across the inside of my workshop. Would a longer outside antenna improve reception at the lower end of the dial?

Any suggestios or comments will be appreciated.

Thanks, Bob


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Sun 18, 2019 12:04 am 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 903
Location: Keystone Heights, FL, USA 32656
First off, I do not have any experience with this radio, but I am fairly good at reading the schematic. If you look at the NA information, resistance checking, steps 5 and 6, it shows that the resistance of L3 should be 91 ohms. I don’t think the light colored coil is L3.

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Jeff
“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Sun 18, 2019 7:54 pm 
Member

Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Jeff:

Thanks for taking a look a this.

The reason I think the light colored coil is L3 is that it is connected to the plate of the RF tube - the 224 tube. The circuit diagram shows L3 connected to the plate of this tube. I get a reading of about 8 ohms for this coil.

I measured the diameter of the wire in the light colored coil, along with the diameter of the coil, and the number of turns to determine if 8 ohms or 91 ohms was a reasonable estimate of the resistance of the coil. Wire diameter is somewhere between .004" and .005", number of turns is 51, and diameter of coil is 1.3". This gives a length of wire in the coil of about 208" or 17.3 feet. Wire diameter indicates 37 gauge wire (.0045" dia) at 523 ohms/1000ft. Total resistance computes out at 9 ohms.

This is how I concluded that the 91 ohms shown on the circuit diagram and resistance table for L3 is in error and that it should be 9 ohms.

I also measured all the resistances at the points indicated on the resistance table you referred to. They all checked reasonably close to the values shown on the table except for plate of the RF tube to 80 filament (L3).

Bob


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Sun 18, 2019 11:01 pm 
Member

Joined: May Sat 30, 2015 11:49 pm
Posts: 903
Location: Keystone Heights, FL, USA 32656
That coil assembly has 4 coils, 3, 4, 5, and 6. Are you able to get a measurement on each one of those?

_________________
Jeff
“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Sun 18, 2019 11:13 pm 
Member

Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Jeff:

Yes I was able to get measurements on the four coils.

They are:

L3 = 8 ohms
L4 = 7.6 ohms
L5 = .8 ohms
L6 = 21.8 ohms

Bob


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Mon 19, 2019 5:04 pm 
Member

Joined: May Sat 30, 2015 11:49 pm
Posts: 903
Location: Keystone Heights, FL, USA 32656
Maybe the fact that it is a different color means it is a different type of wire? All the info I find online shows that L3 is 91 ohms, no space for a missing ".". Wish we had another one to measure.

_________________
Jeff
“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Aug Tue 20, 2019 12:17 am 
Member

Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Jeff:

Even though the coil is a different color it looks like normal coil wire to me. I don't know how to tell if it is different. I agree with you that all the info I could find shows L3 as 91 ohms. I thought maybe someone, when preparing the circuit diagram, just made a mistake. As you suggested maybe someone out there has one of these radios and can measure it.

Thanks for taking the time to look at this.

Bob


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 Post subject: Re: Westinghouse (RCA R-5AC) restoration questions
PostPosted: Oct Thu 17, 2019 2:10 am 
Member

Joined: Mar Thu 03, 2011 8:53 pm
Posts: 1102
Location: Davis, CA
Got back to this radio today. I found that my problem with reception was due to an inadequte antenna. The antenna I was using is a 25 foot long wire inside my work shop. When I strung a wire outside reception improved very noticeably.

Bob


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