Tube Radio Restoration





Introduction: Tube Radio Restoration

This instructable is for a 1948 philco 48-200i case restore.The "i" in 200i stands for Ivory. This is a fairly common radio but it immediately interested me when I first saw it. Only it wasn't in the best condition cosmetically but it reminded me of a old truck in some ways. And I like old trucks. These radios came in two colors orignally, which were mahagony, and ivory. Restoring these old radios is a hobby of mine and I just love seeing them go through the before and after. In this I will briefly show you how I did it. The cost of this restoration as far as the cosmetics go was less than $10 total.  In the picture I have posted my finished product as well as what the radio looked like before I redid it.

Step 1: Preparing the Case

The first thing you got to do is remove the chasis before you can proceed with the case. These radios are great for that reason. They are fully serviceable. Just four screws under the case and it slides right out. Something you can't do easily with more new radios. While I had the chassis out, I went ahead and redid the capacitors(although it didn't hum) and cleaned out the tuneing components. All this was a job unto itself.  Other than that It needed a new tube installed and a dial light bulb. The rest of it worked as it should.  I didn't do anything to the dial face because I wanted it to have some originallity left in it for that nostalgic feel. As you can see from the pictures how they built these radios in the day was great, nothing in it was cheaply made, all the components were metal and made to be replaced if broken.  The hardest part is locating them if they are broken in todays world. But the engineering was just well done and in the USA.   

Step 2: Power Cord

The power cord was appauling. Years old and grimy it was just nasty. It had to go!! Replacing a power cord was easy in this situation. It doesn't have a transformer to connect to in this model, instead it connects directly to the on/off switch and also to a tube. I found that interesting but hey it works. Just two solders and a knot to stop it from pulling out and thats that! The pictures speak for themselves.

Step 3: Prep Time

With that all done I was ready to paint. I turned on the chasis in the background while I worked to make sure it was ticking properly before putting it back together. Preping the radio wasn't hard. Just a good ol' scuff sanding. I covered the dial lense and holes with painters tape to keep out paint where it shouldn't be. From the picture you can see the ivory color but it had been repainted sometime ago. Once I prepped it, I just had to choose a color for it. I wanted to two tone it to give it some personality. So I chose blue and white. White for the speaker grill and blue for the rest of the case. I used krylon peekabo blue. Both were a gloss finish paint. With the music going in the back ground I went to town on it. For the white I just went over the entire case with it getting it nice and wet with two coats. After it dried enough, I taped off the grill area with painters tape and scuff sanded the rest of the case and followed suit with the blue, and for that I did 3 light coats. The white undercoat gave it a nice brightness under the blue. The knobs I did separately and those were more of a challenge due to years of oil and who knows what.

Step 4: Finshed!

After a good day of drying I put it back together. And behold its glory! So much better than it was. It definetly was one of my more easy restores. A lot of these old radios don't have spare parts and some parts are impossible to find so it does come down to having to get creative and make your own parts sometime. Knobs are a huge issue with radio restorations, they are the most handled part of any radio and easily get broke or lost. So it was amazing to me how complete and well taken care of this one was when it came in my path. A lot of my other radios that are waiting for restoration are missing knobs and other pieces that they just don't make anymore..unless I had a time machine... but I don't so unless I could just print them out like on paper I'll just have to come up with other solutions.



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    1 Questions

    Hi i have quite a few tube radios that simply will not power on. The cord is good but there is no power into the chassis. How can i test the components to find what needs to be replaced? Thanks any info is appreciated

    Hello, I would first say does any of the tubes get warm or light up? if they do, you got power coming into the chassis, however if all tubes or cold and none light up, I would see if it has a transformer (some do and some don't) like the one in this instructable does not. If you got a DMM handheld meter I would start by seeing if the wires coming into the chassis from the wall outlet have voltage. If It does, then see if the transformer (assuming it has one) has voltage coming out of the output side. if nothing is then i would say it has a bad transformer. sometimes the on/off switch is part of that circuit and may not be working either and you would know when its switched and has no voltage on either side. Now a radio that does not have a transformer you would do the same test only instead of the wall outlet wires going into a transformer, one goes to the on/off switch and the other goes to a tube. use the DMM at both ends to see if it has power applied when on/off switch is switched to "on". if it does have power the wires are good but the first tube the wires go to after tha are probably bad. Thats the same method i would try with either type of radio. Generally with a old unrestored radio, its the transformer, power switch, bad power tubes (most common and most easy to fix), and least likely would be a broken connection somewhere in the chassis so give it a good look over first then try those steps. Feel free to let me know how it goes. Thanks!


    Check on Ebay for vintage knobs...there are all kinds out there, and some reproduced to suit the old radios. Since this is a rising hobby, and the old is being restored now, there are actually parts out there...who knew, eh? Good luck and I loved the project!! Thanks for the hints from those below to get the right voltages etc...thanks guys! Cheers to all!

    Try getting access to a 3D printer, they are fairly accessible nowadays, for the plastic parts at least.
    And unless you are a purist you could use replacement transistors in stead of those hard to find tubes.

    3 replies

    I have heard of people subing out the tubes with transistors and I have considered it, but to me it takes away from the originality and sound. Its funny but I enjoy flipping it on and waiting for it to warm up. Luckily I got a place here in town that has new old stock for cheap! As far as the plastics go, that is the hardest part if the radio is rare, unlike this one however, this radio is like old mustangs, they are a dime a dozen in many different conditions.

    could you tell us where you have some old stock supplied? Would be nice to order a few for others too? Just wondering if you are willing to give the information:) I have 2 old radios I would love to restore, one is from the early 1940's. Cheers and thank you!

    Its certainly not an easy conversion. Frankly, it makes no sense to do since tube amps and solid state amps are very different. Drop-in tube replacements aren't common and cost a fortune. The point-to-point wiring and wax capacitors don't really stand the test of time either. A non-working tube amp doesn't have much going for it these days. Gutting a tube amp is a particularly heinous crime but if it can't be fixed then its not as bad.

    Excellent paint job! How did you get the clean lines between the two different colors?

    1 reply

    use automotive paint tape to mask off areas around the edge, and either wax coated auto paint paper to mask off the rest as you paint one color:) Hope this helps you in your project:)

    You should consider adding a 1:1 isolation transformer for safety.

    The intriging question ot the line cord connection to radio is because this kind of receiver were called "transformerless", meaning that the tubes filaments are designed to get certain amount of voltage, (35, 50 and 12 volts) and since they are all series connected, the total amount is around 127 volts. The first tube connected is the rectifier, and it draws the neccesary voltage to make the circuit works. Of course, when one filament is gone, the whole receiver becomes "dead."

    Well considering I have repaired hundreds of these tube radios. I have LOTS of tips I can share. Contact cleaner works great for the scratchy volume controls. If the tuner is full of dust you use a pipe cleaner the clean between the plates for better reception.

    For tubes you can leave the original tube in the set a 1n4004 works for bad section of tube diode, triode or pentode.

    have lots of repair tips

    LOVE them old radios!!!

    Outstanding! Reminds me of the radio I built in high school. The second one; the first one blew up :(

    For safety of you and loved ones in your vicinity, I recommend that you replace that rubber grommet with something to keep that metal chassis from slowly cutting its way through that new cord every time it moves, especially since it has no ground safety. Ironically the old cord was saver than your new one. Electricians are shaking their finger at you.

    Otherwise, great work. Glad to see someone fixed up a wonderful old device without making it "better" by gutting it and putting in some $5 powered speakers and an iPod connection, and painting it some ridiculous Andy Warhol scheme. Classy baby blue is definitely a '40s look. Well done.

    1 reply

    You got me there. I will definetly have to go and insulate that area eventually. I do have some ugly models I will "redo" but the case will be the only altering, the chasis will of course be all orginal. I appreciate your comment and glad your like it!

    Thanks for the info. Yeah I understand the tubes in series. Of all my radios, its the only one with out a transformer, but it's also the oldest of the ones I have. I am planning on adding a input on it like I have done on some of the others due to the AM stations here in las vegas are mostly different from what I listen to. And adding a input is easy as tapping into the transformer tube and bypassing the receiving tube with a simple flip switch.

    I was in my middle teen years when transistor radios became available, even though rather expensive for the first few years. I remember being fascinated by tube radios, though, and wanting to learn about how they work. If you have not done so already, find a simple clear explanation of how a superheterodyne radio works and what its advantages over other types of radios are, like a regenerative circuit or a tuned radio frequency circuit. The idea behind using a beat frequency oscillator and how it works to improve performance in the whole radio is genius.

    As concerns the lack of a transformer, these radios economized to make a less costly design. There are usually five tubes. The heating element in each is designed to consume 25 volts. The tube heating elements are in series, so in a 125 volt household circuit, 125 volts is consumed and no transformer is needed for a power supply.

    It has been about twenty years since I had to buy an electron tube. They were becoming less available then. I am surprised you were able to get the tube you needed, but, maybe I should not be.

    When I listened to "popular" music during my teen years, it was most often by means of a tube radio. A few years ago someone gave me a couple of old tube radios. From the two I was able to make one work pretty well, at least for a while. I listened to an oldies station with it and was surprised to rediscover favorite music as I originally heard it with all of the pops, wows, and hisses that are part of AM tube radios. The super-clean sounding FM oldies stations are nice, but, the extra noises made the experience a real authentic trip down memory lane.