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 Post subject: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Sun 06, 2019 6:25 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Hello All,

Yet another purchase due to "radio withdraw"... Saw this on Ebay awhile back and thought the large vertical cylinder tuning dial was interesting---and when I found out that it had vernier drive and internal dial lamp, thought it might be a neat radio to "play" with... Watched it for a few weeks and when no one else seemed interested, made an offer which was quickly accepted...

It uses the same chassis as the "upright" 4RG50 series which at least three people here have posted about with mixed performance experiences...

It arrived today complete with dead vintage batteries and finally was able to try it out tonight. Cleaned battery contacts and installed new cells---and was amazed by performance with original electrolytics ! The air-variable tuning cap is really noisy and plates appear dirty, but sensitivity excellent & selectivity sharp---receives stations nearly every 10 kHz, but need to see what happens tomorrow during daylight hours with favorite low-power DX oldies station. The friction-disk type vernier drive is nice & smooth---seems like several companies used this same tuning cap with attached mechanism and knob in '62-'63 as I have an Arvin & Philco which also do. Volume control shaft very wobbly, but it works fine... Tone is really "trebley" and hope that new caps will improve... The dial lamp is excellent and evenly illuminates the large numbers on tuning cylinder. Really like this plain but unusual radio so far !

Got the back cover detail cleaned and hope to get rest completed tomorrow...

Ebay pic below... Anyone else have one ???

John


Attachments:
ARF RCA 4RG61 EBAY PIC.jpg
ARF RCA 4RG61 EBAY PIC.jpg [ 252.43 KiB | Viewed 643 times ]
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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Sun 06, 2019 6:40 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11015
Location: Powell River BC Canada
A fine arts student or industrial designer might track the styling and branding of this
radio. Technically, it was what it was, but it must have started on the drawing boards just
like a line of clothes does.

Who in this forum studies this aspect ?

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Sun 06, 2019 9:24 pm 
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Joined: Nov Wed 14, 2007 11:37 pm
Posts: 1569
What is the black "thing" on the top left corner of the grille?


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Mon 07, 2019 3:24 am 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Steve---am liking the "simple" styling more and more since the radio performed so well initially. That vertical tuning drum with large numbers and internal dial-light, the excellent vernier drive and the tiny "pinpoint" arrow at "window" bottom is really neat... Am wondering if it was supposed to be some type of "retro" look ???

Metzman---the button at upper-left is for the dial-light which works very well evenly illuminating the translucent white numbers from the inside. Hope I can get a good pic of it when done !

Almost there !

Disassembled, detail cleaned, and replaced electrolytics today---radio is ready for reassembly once pics are taken. Had hoped to finish, but ran out of time...

Someone had done a bit of "hacking" on this set... Both PCB's had cracks and main was missing a corner near volume control which had been a mounting point---repaired affected traces with lead clippings. The battery contact PCB was actually broken in one place opening connection for .003 uF disk cap which goes between audio driver output and ground which could account for the very "trebley" tone. The main PCB was incorrectly installed with one edge just sitting on top of cabinet mounting slot. Several of the interconnecting wires had been replaced with heavier untinned solid copper wiring. Speaker loose due to mounting clip being turned around. Something had rubbed against edge of variable cap plates leaving tiny aluminum "flashings" which caused noise while tuning---carefully "shaved" them off with X-Acto knife. Also, one of the battery contacts had been "patched" with a small, bent strip of same material...

While replacing the electrolytics, noticed that the AGC filter cap was cracked open on one end. Radio must have been used around steel wool as the speaker cone dust cap is full of fine steel strands (see pic below). Center-tapped speaker on this set is interesting as it has a larger magnet and deeper "basket" than typical for others it's size. To clean the chromed metal tuning knob which is integral with variable cap and friction-disk vernier drive mechanism, cut a narrow slot in piece of thin plastic, placed it over knob edge, and used "stubby" toothbrush applying tiny amounts of Windex as needed to avoid it dripping where not wanted and wiping off with Q-tips.

Noticed on the factory RCA schematic in Beitmans that the polarity for AGC filter & audio driver emitter caps is reversed.

Am hoping to get pics taken and have radio back together this week as time allows. Since it appears that battery leakage had got inside of earphone jack and also corroded the external power connector, going to bypass both to prevent any future issues.

Stay tuned !

John


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Wed 09, 2019 2:58 am 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Reassembled & pics taken yesterday...

Removed the audio driver output disk cap from battery board and installed on back of main PCB since earphone jack not going to be used and to eliminate one interconnection. Replaced "hacked" wiring with Teflon insulated stranded.

Inserted batteries and turned on---volume much louder and sound quality now very good with that .003 uF disk cap back across driver output ! There was lower level audio with volume at minimum before, but it still increased substantially when turned up---now very loud at minimum and "blaring" when increased. Unfortunately, the volume control element is bad as I've read is not uncommon with this chassis---appears to be a special part which will need some "engineering" to replace. There is also still a bit of "scratch" left while tuning which needs attention.

But now the good news ! Performance is even better after electrolytic replacement---and even the ANT trimmer was nearly "dead-on" as it was ! Stations across entire dial, even in daylight---and the selectivity is so good that I clearly heard very weak signals adjacent to stronger. This is an excellent little radio and actually fun to tune with the vertical drum dial and super-smooth vernier drive. The tiny pointer at bottom of tuning window is just about as wide as the received signal's position which is a little thing that I like...

Still needs a bit of work with the volume control issue and noisy tuning cap---but WOW, what a great little set ! Think that anyone here would be impressed with this plain looking radio after dialing across the band a couple times...

Pics below...

John


Attachments:
1ARF 4RG61 CVR INS CLN.jpg
1ARF 4RG61 CVR INS CLN.jpg [ 185.95 KiB | Viewed 523 times ]
2ARF 4RG61 CAB INS CLN.jpg
2ARF 4RG61 CAB INS CLN.jpg [ 220.22 KiB | Viewed 523 times ]
3ARF 4RG61 SPKR SIDE CLN.jpg
3ARF 4RG61 SPKR SIDE CLN.jpg [ 202.32 KiB | Viewed 523 times ]
4ARF 4RG61 PCBS CMPLT.jpg
4ARF 4RG61 PCBS CMPLT.jpg [ 225.21 KiB | Viewed 523 times ]
5ARF 4RG61 TUN DETAIL.jpg
5ARF 4RG61 TUN DETAIL.jpg [ 216.93 KiB | Viewed 523 times ]
6ARF 4RG61 CMPLT INS.jpg
6ARF 4RG61 CMPLT INS.jpg [ 219.64 KiB | Viewed 523 times ]
7ARF 4RG61 CMPLT BK.jpg
7ARF 4RG61 CMPLT BK.jpg [ 240.19 KiB | Viewed 523 times ]
8ARF 4RG61 DIAL LITE.jpg
8ARF 4RG61 DIAL LITE.jpg [ 184.19 KiB | Viewed 523 times ]
9ARF 4RG61 CMPLT FRT HNDL UP.jpg
9ARF 4RG61 CMPLT FRT HNDL UP.jpg [ 219.51 KiB | Viewed 523 times ]
10ARF 4RG61 CMPLT FRT HNDL DWN.jpg
10ARF 4RG61 CMPLT FRT HNDL DWN.jpg [ 197.3 KiB | Viewed 523 times ]
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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Wed 09, 2019 3:15 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13694
Your work makes even the mundane eye catching, awesome restore!

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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Thu 10, 2019 12:13 am 
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Joined: Feb Mon 21, 2011 4:19 pm
Posts: 201
Location: San Marcos, CA 92069
I'm always impressed by how much you manage to improve the looks of your restorations!

I've an interesting thought, have you thought of changing the dial light to LEDs? What I am thinking is one wired to be on all the time for ambient light in the dark, and a second (or using the switch to bypass a resistor) brings up the brightness when the dial light switch is pressed?


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Thu 10, 2019 3:08 am 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Thanks much, Guys !

Tom---it's a set you need to put on your "list" !

Nash---Yes, did think of an LED since I have several left over from other projects, but the dial-lamp in this set is neatly installed in center of cylinder and works so well I hate to disturb it. But do like your idea about dual-brightness having it illuminated when power applied and using button to decrease resistance for brighter light---makes me think of the old W-E "Princess" telephone dial light where dial is lit dimly at all times but goes to full brightness when handset lifted...

John


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Thu 10, 2019 11:25 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Played with this radio again this afternoon tuning back & forth across band---it keeps pace (based on memory) with several sets that have a tuned-RF amp stage. Once I get the volume control and tuning cap noise issues resolved, will be interesting to compare it with the best...

John


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Fri 11, 2019 11:03 pm 
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Joined: Aug Wed 26, 2009 1:50 am
Posts: 1463
Location: Mesquite NV 89027 (from Coventry, UK)
Very nice John. I like the vertical tuning dial, don't remember seeing anything like it before.


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Sat 12, 2019 1:26 am 
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Joined: May Wed 01, 2013 10:05 pm
Posts: 1990
Location: Rayleigh, BC, CANADA
Same here, never seen a vertical drum dial like that either.

Very nice looking set John, Great job!

So the W-E Princess phones had a L/H brightness, interesting.

I remember well my parents had one in the bedroom, it never got brighter when you lift the handset, Northern Electric must be different.

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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Sat 12, 2019 5:28 am 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Thanks much Guys !

Colin---Same here on the unique good-sized vertical drum dial which is what sparked interest along with its dial-light.

Rocco---Haven't heard from you in awhile and was recently thinking of sending an e-mail to see if all okay ! There was a switch on back of the Princess base for the lower brightness "night-light" which could be turned off---maybe your folks didn't use it ?

John


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 Post subject: Re: Plain but interesting RCA 4RG61 project...
PostPosted: Jan Sat 12, 2019 8:33 pm 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 5767
Location: Indianapolis, IN
Just AMAZING !!!

Thought that this radio was "special" when first turned on after refurb as it received stations all across band during the day including a couple I didn't recall hearing before---and even though some were very weak, there was enough clean audio amplification to hear them clearly when volume turned up !

So today I pulled out the Panasonic RF-2200 for comparison around 1:30 PM in the afternoon---and was truly amazed that this little set kept up with it across the entire AM broadcast band without the help of any RF amplification ! Even the selectivity was a tiny bit better (by ear) with a weak station adjacent to 700 WLW ! Had slightly "tweaked" the IF's on RCA earlier and only the 1st showed very small improvement which was impressive since radio had been "hacked" with in the past...

The tuning cap noise is almost completely gone now from use and am contemplating how to replace volume control without having to heavily modify the knob...

Is this just one of those "rare" sets that is simply extra "hot" due to a chance assemblage of "more excellent" parts or is the design that good ???

Am now even more interested to hear from anyone else who has one or it's vertical, more stylish "sibling", the 4RG5x which uses same chassis...

John


Attachments:
ARF 4RG61 RF2200 COMP 1-12-2019.jpg
ARF 4RG61 RF2200 COMP 1-12-2019.jpg [ 229.6 KiB | Viewed 366 times ]
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