We picked up this radio from the local antique shop for just £3. The internals don't work anymore, though they sure do look cool.
The total cost of everything was around £60 - £70. Everything was bought new, and this speaker system only uses one speaker, so we're left with a spare.
6.5" speaker. This is the same diameter as the original, so it could use the existing clasps.
180w Amplifer. This is one of those dirt-cheap ebay ones. I'm sure it won't actually pump out 180 watts (per channel), but for this kind of basic system, it's fine.
12V SLA battery. a 1.3Ah battery from maplin. It's small and cheap. 1.3Ah may not be enough though, we'll see.
Cigarette lighter. A standard 12v cigarette light from a car. This provides somewhere to plug the battery in to a charger.
Fancy Missile-style switch. This switch will be the main power isolator for the battery.
Cables: Short length of speaker cable, mono 3.5mm couple and 2 3.5mm jack-jack cables.
These are the main things. Not included about is bolts, washers, screws, or the scrap bits of wood.
Step 1: Disassemble the Radio
I removed the screws holding the back panel on, and then removed the internal parts by removing more screws, unattaching the tuning needle, undoing the speaker, and taking the knobs of the dials on the front.
Our internal parts, the actual radio, don't work, but since it's very old it'll be destined for either a car boot sale or freecycle as I'm sure someone will want it.
I kept the knobs for the front dials because I will put them back on the front to make it look more genuine.
I had planned to undo the rotary switches from the amp and wire them up to the front, but after doing this, I noticed the sound quality dropped significantly, due to interference I would guess.
The next step was to vacuum out 50 years of dust from the radio.
Step 2: Something to Mount the Parts To
I cut a piece of wood to fit in the cabinet to mount the amp, battery and such on to. It bolts on to the underside where the original internals mounted to.
I cut groves, albeit too big, in the wood so it would slide right in around exisiting parts.
I didn't take a pic of this before I began mounting parts to it, but as you can see, it's an old shelf cut to size. It doesn't need to be anything fancy as it won't get seen.
Step 3: Installing the Amp and Battery
The amp was screwed on to the board, and the wires to the speaker connected to one of the outputs.
Now would be a good time to talk about the fact there is only one speaker. This cheap amp can't be bridged, so only one channel is being used. Because one shouldn't really leave a channel without a load on it, I will put a LED or bulb on this channel, to use up the current.
And to get around the fact that just the left or right channel is going to be heard, I will use a mono 3.5mm jack coupler to merge both the left and the right channel into eachother to create both stereo signals on each channel.
To install the battery, which I wanted to keep upright, I placed it on the mounting board and then glued and screwwed scrap pieces of wood around to keep it in place. It shouldn't come up over the scraps of wood because the battery is heavy, but I can strap it down with a piece of bungee if needsbe.
Step 4: Installing Parts 2
I wasn't sure of the draw of the amp, so I didn't both putting a fuse in, the amp is pretty low power so it shouldn't be too dangerous. It's also low-powered enough that I can use a power switch inline with the circuit, rather than through a relay.
I wanted to make the original tuning board on the front of the radio light up, so I installed some LEDs where the original illumination light was. When charged, the battery holds a 14.7V charge, so using http://led.linear1.org/led.wiz I calculated what resisitors to use.
Step 5: Installing Parts Onto the Back
The rear of the unit is a piece of hardboard that has several holes in from previous ports.I blanked most of these off with a strip of hardboard cut to size. Holes were drilled in this piece for amp controls.
I drilled one of the holes at the top bigger and put the cigarette lighter in there.
The switch was wired in near this, which switches the amp on and off, bypassing the original switch on the amp which I removed.
I also mounted my 3.5mm jack coupler on the back too. In hindsight I should have got a proper surface-mounted connector, rather than one that just wedges in. I will secure this with a bit of hot glue and maybe a cable tie or two.
The rear of the coupler, using a jack-to-jack cable, was wired straight to the amp.
Another jack-to-jack cable needs to be carried around with this amp to plug things into it. One could have a wire that sticks out and can't be removed, or maybe a retractable one, like one a ski-pass.
The mounting board with amp attached was installed for the last time in the cabinet, and then I lined up the dials with the bottom of the back-plate. I made markings and drilled them out.
The amp came with some shiny knobs which I have installed for now. It's not hard to replace these knobs with some nicer looking ones if I find some on the bay.
Step 6: Bonus Step
Hopefully, your resurection of an old valve radio shouldn't include this step.
This step shows how I went about replacing the broken cloth of the front of the unit.
First thing to do was remove the speaker and speaker bracket from the front piece of wood.
Then I removed the piece of wood by rotating the clasps 90 degrees to loosen the wood and remove it.
I then removed the speaker mounts which are just bolts with a fancy flush-mount plate.
The existing cloth was unceremoniously torn away from the hardboard.
I used a belt sander to remove the felt, being careful not to damage the wood. I touched it up with some sandpaper and made sure it was smooth.
After reattaching the flush-mounted plates, I used instant contact adhesive to glue a sheet of new cloth to the hardboard. It's important to use an uncut bit of cloth, rather than attempting to pre-cut it.
I placed a heavy weight on a flat piece of wood over the glueing area to make sure there were no bubble or seams.
Once the adhesive has dried, I went round the outside of the wood with a scalpel to remove excess cloth.
I used a reamer and a pencil to make the holes in the cloth. Don't use a drill, it will snag and rip your cloth apart.
I then put the piece of wood with new cloth attached back in the cabinet, reattached the clasps on to the lugs and then reattached the speaker.