Instructables

Tube Radio Restoration

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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.
 
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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.   
dsandds200315 days ago

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!!!

zomfibame1 year ago
nice!
RangerJ1 year ago
Outstanding! Reminds me of the radio I built in high school. The second one; the first one blew up :(
thegoom1 year ago
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.
Sparker94 (author)  thegoom1 year ago
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.
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.
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.
Sparker94 (author)  mattthegamer4631 year ago
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!
Sparker94 (author) 1 year ago
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.
Phil B1 year ago
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.