Sparton Junior restoration
 

I picked this radio up a few months ago from a local antiques shop. Right away I noticed the switch sticking out the side and the 183 output tubes were missing.
I pointed this out, negotiated a better price and took it home :)

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It's in pretty good shape overall. Just a little separation of the cabinet and some corrosion on the chassis. Underneath, there's evidence of some old repairs.
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It's fused and supports multiple line voltages.
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First up, I tacked some new caps in place just to try it out. I don't have a pair of 183s, but thanks to other forum members I was able to sub in some 71As :)

Notice the metal bracket coming off the volume control ? That's where the power switch would normally be located. Someone had removed it, drilled a hole in the side of the cabinet and remounted it there. More on that later.

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I powered it up with a variac and dim bulb. No smoke so I increased the voltage until the filaments were glowing nicely and I had reasonable B+. Nothing but static out of the speaker though.

I touched the grid caps on the 224s and got a hum at the 2nd stage, but nothing form the first. A little investigating turned up an open coil :tears:
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Luckily, the break was just at the end and I was able to repair it. It's alive :hdphones:
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Now to restuff those old caps. I clean out the little metal box, stuffed 4 new 0.033 uF caps inside and filled it with wax. A power resistor gave out and I had to use a modern looking one.
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That left the big filter cap. Sparton mounted it by punching a hole in the chassis with bent over flaps and shoved the soft aluminum can in. I've had to deal with this once before. They are a bitch to get out.
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Finally I managed it and was treated to a nice label which had been hidden before - 16 whole microfarads :D
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Now, I can cut off the bottom and restuff it.
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I used a little JB Weld to reseal the can.
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That leaves the scratchy volume control. I carefully unsoldered it and popped it open. I was quite surprised at what I found inside. That is one sweet potentiometer :yes:

I used a little deoxit and no more scratchies.

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Next, I polished up the chassis. First a little naval jelly, then Noxon metal polish and finally some simichrome polish.

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Finally, I determined that the power transformer and shields were originally painted silver/grey. I chose to use some Rustoleum specialty metallic silver.

I left the transformer soldered in - just removed the bolts and slipped some paper in to protect the rest of the set.
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I still need to track down one of the missing tube shields. Here it is with the one good 183 tube I do have. I'm tempted to sell it rather than find a twin. They are quite expensive. Besides it has more than enough volume with the 71As.

Now back to that power switch and the hole in the side of the cabinet. After a bit of detective work and tinkering, I was able to remount the power switch on the volume pot and make it work - most of the time. Every 50 or so flicks the little wire stub wouldn't flick the switch over. When this happens, the only way to fix it is to remove the chassis and manually flip the switch. I suspect this is why someone relocated it to the side of the cabinet.

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I've gone back and forth over what to do about it. Currently, I'm going to leave it mounted in the side. I'm not going to refnish the cabinet and any patch job I do is going to be very visible and I'm not crazy about having to pull the chassis next time it gets stuck.

Maybe build up the ball on the power switch with a little bit of epoxy-then you can shave it down until you have the perfect fit.

This switch requires a lot of force to flip. The little "L" wire is adjustable in and out. The problem seems to be that if I extend the trip wire too much, it won't make it past the switch ball. If it's in too far, it will slip past without tripping the switch. If I could locate a power switch that requires less force, I bet it would work a lot better.

Of course, I could replace the whole assembly with a more modern combo pot + switch, but where's the fun in that :D

I wonder how other manufacturers managed it :scratch2: The other late 20's - early 30s radios I've seen have dedicated power switches.

As for the cabinet, I only used Howard's Restore-A-Finish walnut, Feed-N-Wax and a whole lot of elbow grease.

It does a great job on blemishes and scratches. With a little steel wool and rubbing it smooths out alligatoring too.

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Before
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After
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I also replaced a couple missing braces and tightened up some loose joints.
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Here it is ready for the chassis. I really like that patina.
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I think is the way the repwood grill is supposed to go :scratch2:
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Nice job on that set. I have one I got about 20 years ago. The are realty great performers kind of a mix of 20s t r f meets 30s ac. Allways wondered what that big empty hole in my chassis was for.does anyone have a spare lyric to fill in that hole?

I wonder if the switch would work better if you bent that metal tip just a further outward so it makes better contact with the switch ball?

I like what you're doing with this set, preserving as much as possible the original finish.

A lot of early sets had a power toggle switch on the side so this one doesn't really look out of place. That switch has a long threaded shank which is used for just such a purpose, going through thick wood. Why would they use such a long shank if it were to be mounted on the volume control? Is there evidence that a switch ever was originally mounted there? Or did someone substitute the long shank switch? The wiring might give a clue. That being said, you could try a modern short shank toggle on the pot; should have less force required. Maybe a ready-made wooden button plug properly finished wouldn't look too awful stuck in the switch hole?

BTW, that pot was designed by an engineer the week that the bean counters were on vacation. Built to last!

Ah, I hadn't thought about that long shank - good point. I got the idea that it should be mounted on the volume control from a couple places. "retrochad" demonstrates one in a YouTube video with the switch on the control. I also found this photo online with a switch on the control.

That being said, the mounting ring on my control sure looked virgin. No scuff marks at all. The wires look original and are long enough to mount the switch in either position.

I thought about plugging the hole with something like that. It's a little jagged around the hole, but I suppose some filler could take care of that.

LOL - I was reluctant to seal that pot back up and hide it away. It should be out on display.

I wonder if the switch mounted on the side was factory. Maybe they found that positioned on the volume control it wasn't reliable causing callbacks and so went to the side mount in later production.

That restoration job really looks nice! On mine, yes there is a toggle switch mounted on the volume control for the on/off function.

I'd been holding off on finishing this project lo these many months in the hopes of finding a matching 483 output tube. It doesn't seem like that's ever going to happen - at least not one I can afford. I never found a tube shield either. Ah well.
So, I left it modified for the 71As, installed a new power cord and buttoned the set up.

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Wow, I'm amazed how nice the finish came out on that set! Where'd you find that cloth wire for the line cord?

-Jason

Bob,
I hope this sheds some light on your switch dilemma. This is a photo of the switch originally used in your set. It has a notch in the handle for actuation by the wire link. The collar on this one is ¼ inch long. If you can find a short collar switch it’s easy to file the notch in to the handle and the short collar will make for easy operation by the wire link. The long collar shaft takes a lot more force to flip.

That is a great set. I have one I’ve yet to restore but there have been several on my bench over the years. Sparton was good at coming up with their own tubes hoping to corner the renewal market. National Union is about the only maker I’ve found that supplied replacements for some Sparton numbers. The 183 tubes are non existent as you’ve discovered. Luckily they were in my set when I bought it about 6 years ago. The first one I restored was back in the early ‘80s and they were missing. I found a long ago published hint in a radio magazine concerning availability of these tubes that was written by a service man who could not find them- even then. His remedy was to wire the filaments in series and use a pair of 45 tubes. It worked quite well and the power transformer didn’t seem to mind at all. 45’s are pricey but also easier to find. 71A tubes have a maximum of 180 plate volts. Check the voltage on your set to be sure it isn’t pumping out around 250 which is the maximum for the 183’s and maybe the 45’s as well. If you don’t play the set very much it may be a non issue in the long run. Most Sparton sets of this era tend to run tubes at or near maximum operating voltages- another stab at selling replacements, no doubt.

Best regards,
Rick

Thanks! I was lucky in that none of it had flaked off - just some alligatoring.
I got the line cord from Antique Electronic Supply. I've also used some from radiodaze that's very nice as well.

Thanks for the info Rick. I suspected this wasn't the original power switch since it requires so much force to flip. I picked up a Ware B-1 chassis recently that has a toggle switch with notch just like yours.

I'll be sure to check the voltage ASAP. I do have a single NOS ST 482, two fair ST 182s, and two fair globe 182s. I'll be using a pair of those in my 931 Equisonne.
I think I'll just sell the one sweet globe 483 I do have.
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Looking at this thread again I think I need to replace the paper caps in mine. When I got it about 8 or 9 years ago I think I just put new electrolytics in it and for some odd reason didn't think it had paper caps...now that I know they were inside of a metal box I will replace them. Mine has problems with intermittent changes in volume and it must be due to those caps.

Cloth-covered line cord was used up to the mid thirties. About 1937 radios pretty much had rubber-covered line cord and molded plugs (except for resistance line cords which continued cloth-covered.) Here's another source for cloth cord including several types and colors. I've used their black twisted stuff for 1920's fans.

http://www.sundialwire.com/