Silvertone 1708 1941 5 Tube Farm Radio Restoration

[DavidBalding]

I recently was given my great grandad's (on my dad's side) radio that was pulled out of an attic in my grandparents house that they have lived in since 1976. There was a squirrels' nest that had been built in the back and sitting on top of the chassis. This radio is a Silvertone 1708 dating back to 1941. It had two tubes that had been replaced with dated labels of 1947. Overall the cabinet is in great shape. The radio chassis itself is rusted pretty good and will need to be recapped and restrung before anything else. I will be documenting the progress of the restoration thoughout here for anyone interested in seeing and learning.

 

[dcgillespie]

Ooh! Battery power! Will definitely be following along!

Dave

 

[63pontiacgp]

Nice looking radio, I don't think it's a 1708. The 1708 "Worlds Fair" radio is an AC set with 8 tubes from 1933.

Edit: It's a 7108, Uses 90 Volts for operation and 1.5 Volts for the filaments.

Mike

 

[gadget73]

the low volt filament battery stuff is interesting. Basically instant on too, they warm up very fast.

 

[Catmanboo]

The classic "farm" radio so- called because back in the day many farms / rural dwellers had no electrical service. You can build a quick power source from common d-cell batteries connected in series for the 90 volt b+ & parallel a handful for the filament voltage or just use a no.6 battery if you can find one. There's very little to restore there, whatever rodent brand nested in there was very kind to it. I've seen the horrible results when they were thugs. Clean it up, power it up & (hopefully) enjoy as-is. You will need a long wire antenna though.

 

[Catmanboo]

The cracked base on the tube 2nd from right should not be cause for concern, just thin brittle cracked brass. As these radios have no AC power supply, there's no associated components to foul things up, & these were not subject to heavy use back in their day, big battery blocks were expensive & didn't last long under extended load.

 

[electronjohn]

The classic "farm" radio so- called because back in the day many farms / rural dwellers had no electrical service. You can build a quick power source from common d-cell batteries connected in series for the 90 volt b+ & parallel a handful for the filament voltage or just use a no.6 battery if you can find one. There's very little to restore there, whatever rodent brand nested in there was very kind to it. I've seen the horrible results when they were thugs. Clean it up, power it up & (hopefully) enjoy as-is. You will need a long wire antenna though.

Common 9V batteries in series do a fine job for the B+. Current drain is low, so they should last a long time.

 

[Catmanboo]

Common 9V batteries in series do a fine job for the B+. Current drain is low, so they should last a long time.

I did that with a basic 4-tube Silvertone long ago , still have it. Makes for much smaller pack surely. They didn't seem to last, though, but may have been the batteries I used. Gonna give that another go someday with fresh alkalines & a few D cells paralleled just to hear this thing again. Thanks for the reminder!

 

[63pontiacgp]

Common 9V batteries in series do a fine job for the B+. Current drain is low, so they should last a long time.

I agree that the 9 volts would be good for testing. With any volume though they won't last long.

Mike

 

[DavidBalding]

Attached are more pictures of the radio removed from the cabinet. As far as powering, I will be using 10 9V batteries in series and two D cell batteries in parallel for testing. Once proven to work, I will build a Battery Eliminator to power it up permanently. The two D cells of course for the filiament power and the 9 volts for the grid and plates. Have new radio dial string here to restring it and all 11 caps that I will be replacing have arrived as well. Waiting on the rubber mounts to come in next. Just finished removing all the rust from the squirrel urine and oiled the tuner coil unit as it was very stiff. Now it moves freely so that the dial string won't break once replaced. Enjoy the pictures!

 

[DavidBalding]

The classic "farm" radio so- called because back in the day many farms / rural dwellers had no electrical service. You can build a quick power source from common d-cell batteries connected in series for the 90 volt b+ & parallel a handful for the filament voltage or just use a no.6 battery if you can find one. There's very little to restore there, whatever rodent brand nested in there was very kind to it. I've seen the horrible results when they were thugs. Clean it up, power it up & (hopefully) enjoy as-is. You will need a long wire antenna though.

Luckily as a Ham Radio operator, I have a 130 foot wire antenna up at 40 feet to bring in AM stations.

 

[Catmanboo]

I'd power it up for functional check prior to rebuilding the guts just for schitzengrins.You may find that it's still kicking. Then do your thing, see if it improves. That's the most elaborate battery radio of that Era I've seen yet, already looks damn good! Have fun, good luck, yer longwire should exceed expectations.
de K8CAT

 

[Catmanboo]

I agree that the 9 volts would be good for testing. With any volume though they won't last long.

Mike

That be a fact, my past experience.

 

[DavidBalding]

Restrung the radio dial with the new radio cord. Couldn't have asked for a better result on that. Will use rubber cement once the radio has been aligned to lock the dial indicator on the cord as well as the two eyelets. Rubber mounts have been installed. The mounts came from 'Renovated Radios LLC'. The dial cord I ordered from cdcandy on eBay. Got setup for the caps. Now some will argue that the modern film caps have no orientation, some will argue they do. The orignal have a mark showing the foil end. The modern ones do not. I did the same measurements as my last restoration before using a lamp with an incandescent light bulb. With the osciloscope, I put the ground lead on one end and the probe on the other end. As you can see on the scope, one direction had more noise induced from the AC line cord being held against the cap. The other direction had less noise. The configuration of the ground lead with the least amount of noise would be the foil end. I mark those ends with a sharpie and as I replace the caps one at a time, I make sure the foil end goes towards ground. Again, I'm not going to argue if it helps or not, but the scope doesn't lie. The console I restored this way previously has had no hum or noise within the unit. I figure with a few more minutes added to check, no harm if it doesn't do anything. I wound up reading the parts list inside the radio wrong and ordered three caps the wrong value, so I did not finish last night with the recapping. The three caps should be here in two days from Mouser.

My 10 year old son did find my next project radio today at the local thrift store; A Stromberg-Carlson 952-H from 1938! Kid is learning quick! I'm going to really enjoy fixing that one up.

 

[DavidBalding]

Restrung the radio dial with the new radio cord. Couldn't have asked for a better result on that. Will use rubber cement once the radio has been aligned to lock the dial indicator on the cord as well as the two eyelets. Rubber mounts have been installed. The mounts came from 'Renovated Radios LLC'. The dial cord I ordered from cdcandy on eBay. Got setup for the caps. Now some will argue that the modern film caps have no orientation, some will argue they do. The orignal have a mark showing the foil end. The modern ones do not. I did the same measurements as my last restoration before using a lamp with an incandescent light bulb. With the osciloscope, I put the ground lead on one end and the probe on the other end. As you can see on the scope, one direction had more noise induced from the AC line cord being held against the cap. The other direction had less noise. The configuration of the ground lead with the least amount of noise would be the foil end. I mark those ends with a sharpie and as I replace the caps one at a time, I make sure the foil end goes towards ground. Again, I'm not going to argue if it helps or not, but the scope doesn't lie. The console I restored this way previously has had no hum or noise within the unit. I figure with a few more minutes added to check, no harm if it doesn't do anything. I wound up reading the parts list inside the radio wrong and ordered three caps the wrong value, so I did not finish last night with the recapping. The three caps should be here in two days from Mouser.

My 10 year old son did find my next project radio today at the local thrift store; A Stromberg-Carlson 952-H from 1938! Kid is learning quick! I'm going to really enjoy fixing that one up.

Edit: With no model number listed on the next project I guessed at the model. Turns out it's a Stromberg-Carlson 410-H from 1940. Very close in comparision.

 

[DavidBalding]

Chassis has all new caps. Tubes cleaned up and reinstalled. Remounted chassis in radio cabinet. I did connect two "C" batteries in parallel to the A side and got .167 amps of power draw which is a good sign. I couldn't see filiment glow which is why I did an amp draw reading. The batteries also were not new "C" batts so could explain the lower reading. According to the specs .25 amp draw should be seen with full power on the A side and .0095 on the B side. I haven't picked up the 9 volt batteries yet so that will be the next test; applying 90 volts DC on the B legs with 1.5 volts DC on the A legs and see if she sings. Looking forward to alignment. This will be the first radio alignment I have attempted and the first time trying out the Siglent SDG 1032X and the Tiny SA.

 

[gadget73]

Not much visible glow on those 1.5v tubes

 

[Catmanboo]

Not much visible glow on those 1.5v tubes

As in very hard to see, even in darkness. If they had noticeable glow, battery life would be very limited. That is the most complex, deluxe model of battery radio from that era I've ever seen. Very cool piece indeed. For the filament supply, a no.6 dry battery or even 2 in parallel or a stack of alkaline or rechargeable D cells paralleled is the way to go. Hope all goes as planned with the test run. Just use a long wire for antenna. Grounding to earth may help but shouldn't be needed.

 

[63pontiacgp]

Not much visible glow on those 1.5v tubes

Also, the few battery sets I have had are almost "instant on" versus AC sets that need a bit of warm up time.

Mike

 

[Catmanboo]

Also, the few battery sets I have had are almost "instant on" versus AC sets that need a bit of warm up time.

Mike

Due to the miniscule filaments in the tubes. I "dissected" a dead one long ago, filament was akin to a cat whisker & was hard to find at first. Doesn't take much to heat that thing up. Feeling these types of tubes for operating heat to look for a dead one is an exercise in futility.