Antique vacuum tube radio gets a guitar/aux jack input! Coronado/Philco/Zenith

This is an antique 1940's Coronado/Skogmo model 970-B AM tombstone radio. The cabinet was really in disrepair with heavy chips along the bottom, loads of stains and scratches.

See a diagram here: https://joyemusic.com/wp-content/uplo...

See FAQ below...
The electronics didn't really work either. All the bulbs were burned out, of course, so I replaced them all with LEDs, because the bulbs were really hard to replace -- You had to remove the radio chassis to access them! The volume control was shot; it was skipping and scratchy, and even my tricks to restore it failed, so I replaced it with a new unit. All the copper, glass and plastic was cleaned. Power supply caps were bypassed. Actually, the main power cap was severely overheating, which caused the main voltage to drop so the radio to not work. The antenna was missing and was hot-wired in an unusual manner too.

The main speaker cone was shredded since the grill cloth was destroyed, but the speaker didn't have a permanent magnet, so the magnet coil was a critical part of the radio circuit and had to remain in the cabinet. I replaced the speaker with a vintage 1960's Hammond Organ speaker and tapped it into the speaker transformer. The power cord was replaced, a new antenna installed, and the chassis cleaned out.

An auxiliary stereo/mono input jack was installed to bypass the radio so you can play your music via smart phone, guitar, laptop, etc. through the vacuum tube amplifier and built-in cabinet speaker. It actually sounds really nice and works well. I just had to find a vacuum tube between the AM radio and amplifier stage to tap in to. I installed a stereo jack with switches so either a stereo or mono jack could be used.

The cabinet itself was refinished by a friend of mine. He stripped it, added a new mahogany veneer, stained the whole thing and poly-coated it for a nice finish. It looks like a million dollars!

This restoration job was a gift for my neighbor who retired from the Air Force and moved to Alaska. It'll be a great piece for his man-cave!

FAQ:
Q1: I have a radio like this, can I do something similar?
A1: Absolutely! If you have a working radio where the amplifier and radio portions are not clearly separate (all on one chassis), then I would recommend going straight to the volume control. Most likely, all you need to do is hook up a switched auxiliary jack to the wire in the middle of the volume control. If the volume is too weak, you may need to add a gain stage for the signal coming in the jack, or -- for more advanced people -- see if there's an earlier gain stage before the volume control you can tap into for more gain.

Q2: Can I have a diagram showing how to hook it up?
A2: Here's a diagram: https://joyemusic.com/wp-content/uplo...



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