EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Wil_Bloodworth on November 13, 2023, 10:02:33 pm
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I have the chance/opportunity to pick up, what appears to be, a nice 1933 Philco Model 44 radio. I'm not sure it still works but it appears to have been keep indoors (not in a garage) and is in good shape.
The schematics seem to be somewhat available. Have any of you ever worked on one of these? Would you do it again?
[attachimg=1]
Thank you,
- Wil
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3-gang tuning capacitor so it almost certainly has a tuned RF stage. Better than most, so it should be a good performer.
Edit -> on closer inspection it looks like the tuning capacitor has two large and two smaller sections, the smaller ones possibly for short wave bands.
https://philcoradio.com/gallery2/images/1933d%20-%20Fall%201933/1933d.h%20-%20Model%2044H/image_04.jpg (https://philcoradio.com/gallery2/images/1933d%20-%20Fall%201933/1933d.h%20-%20Model%2044H/image_04.jpg)
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I scrapped one for parts nearly 60 years ago as a teenager. Yours looks very nice and worth restoring. Electrolytic capacitors will be dry and dead, and the tubes of that era are getting hard to come by. The one I parted out had many mica capacitors which should be just fine today, unlike the wax dipped paper used in later models. Resistors could be fine, or could have drifted badly over the years. By the way many of the components appeared very different than later decades. This radio was fairly early in the standardization of the electronics industry and styles in use then didn't last too long. By todays standards the circuitry is very simple, though the wiring methods are confusing to those who entered the hobby after PWBs took over. Be cautious of the high voltages. One hand in the pocket, be wary of charge stored in capacitors. The main object of my scrapping was that big power transformer seen at the left of the chassis top view. I still have the high voltage power supply that resulted.
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These big old radios sound great. The big ones are usually not as valuable as the smaller table top ones because it is hard to find the room to collect more than one or two. But they do have better sound.
The speaker is usually an electromagnet rather than a permanent magnet and the high voltage supply goes thru it. It uses the speaker electromagnet not only for the speaker but as a big choke inductor to filter the High Volts. So be careful. If the speaker is damaged there are lots of people who have used different materials to replace even the cone.
Real purists will gut the old cap cans and stuff in new caps for the look. Others will just disconnect the old caps and wire in new caps under the chassis. The old big electrolyte caps had quite a large range of tolerances in their capacitance, so do not be too fussy in choosing replacements.
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I haven't opt'd to purchase this one (yet). He wanted a bit too much for it in my opinion so I'm going to finish the one I'm working on now before tackling anything new.
- Wil
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I haven't opt'd to purchase this one (yet). He wanted a bit too much for it in my opinion so I'm going to finish the one I'm working on now before tackling anything new.
- Wil
Out of curiosity, what is he asking? I do expect prices in this market to drop as people of the age are starting to drop out and AM broadcasts are declining.
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https://dallas.craigslist.org/dal/ele/d/plano-philco-radio-model-super-cool/7681831515.html
$65
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https://dallas.craigslist.org/dal/ele/d/plano-philco-radio-model-super-cool/7681831515.html
$65
That actually seems like a good price to me. If I lived in the area I would buy it, largely because of the connection to my past. Cabinet is in great shape and it appears to all be there. The biggest holdup is whether you have room and interest to keep it.
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It's not the price that concerns me at all. My main concern, which causes the reservations of purchasing the Philco, is that I am in the middle of attempting to fix the first radio I've ever tried to restore and I'm not sure I'm going to be able to pull it off. I just don't have the necessary tools or knowledge so if I fail, it will all just go in the trash and I'll probably just end up learning how to fish instead.
- Wil
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It's alright to fail more than once in a project.
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That is true. However, if I get stuck with something that isn't working, I don't have any local resources who can help get me unstuck. The online resources I feel that I could rely on are probably going to ask things I don't understand or have no way to measure. All the pessimism aside, this is purely conjecture on my part as I don't even know if I will get stuck.
It's akin to a blacksmith stumbling across a Ferrari that has been left in the forest for 50 years and he's decided to get it running. While the blacksmith has amazing intentions, hopes, and dreams... reality always shows up.
- Wil
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If you are careful with the mechanical work you will not destroy the value. If you come up against a bigger obstacle than you wish to cross you will have little trouble recovering your investment.
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Wil: Do not despair and do not sell yourself short.
Your first attempt is not the easiest one but it is not horribly complicated.
People designed and fixed these things with the limited test equipment available at the time.
Things like oscilloscopes were not available. A nano VNA was as far away as "Star Trek", you could probably buy a running automobile for what it cost for a top of the line multimeter.
The best repair technician I have ever met mostly used only a 30 MHz scope, he was very disabled by arthritis and could not walk and could barely light a cigarette with his gnarled hands, but he always fixed the thing. He did have digital multimeters but he used an analog multimeter because he did not like the digital readout ones.I use both analog and digital, digital meters are better, I buy interesting analog meters at Hamfests for $10 because they are cool and do not take up much room in the shack. Besides, some of the military ones have Kilo Volt capabilities that I use once or twice a year. You need special High Volt probes and test leads for this. You don't need this now.
This is part of the Test Equipment Anonymous (see the Test Equip Forum) it is referred to as GAS or Gear Acquisition Syndrome and cannot be treated with conventional psychotherapy.
On your first repair: Replace the components one by one, and try to understand where they go on the schematic while putting them in the actual radio, that thing is eminently repairable.
Remember, you are in it as a hobby, there are lots of people here who are professionals and have worked in electronics for decades after getting various degrees. This is their living. Yours is a hobby. Hobbies cost money and it is quite rare for a hobby to generate money or even break even. I have managed to make a little money fixing things to buy more stuff, but I do not think I could actually make a good living doing this stuff.
Stick with your first repair attempt, Old Radios are out there and will come to you when they feel like it. If the neighborhood finds out you are interested in old radios, so many will appear that you will be sorry anyone knows about your hobby.
After you have replaced the components you think need replacing, and the tubes light up, you can see what sort of test equip you need. On your radio either all the tubes will light up or none, as you know (see, you already know something that most people do not)
Sometimes the thing comes to life and needs very little adjustment.
All you need to tune the thing is a signal, whether that is a good AM station or a generator with AM modulation. If you get some sound out of the speaker, you can tune the radio.
Again, go to some Hamfests and talk to people, someone WILL have some stuff that you can buy cheaply.
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Wil, that is very, very cheap for its state. I was tempted to get it but, as you can imagine, the problem is the large room to work on this (and the wife approval factor, which is close to nil for a new project).
I can help with repair tips if needed (I live on the same general area).
Good luck in your decision!
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Wallace has excellent advice. Do note that all or none tube lighting up is a feature of most AM radios from the mid/late 1930s through the end of the tube era, but is not true for the Philco 44 you are looking at. The transformer has a 6.3 VAC winding and all the tubes are connected in parallel to that winding. This does make it easier to find a tube (or tubes) with a burned out filament as they will be the ones that don't get warm/light up.
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If I don't have a tube tester, can I not just pull out each tube individually and apply the appropriate/required amount of DC voltage to the filament pins to make sure it lights up? Is there any reason to even do this if I have already tested continuity on the filament pins?
- Wil
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The "cold" heater resistance of these tubes is not specified, so a "continuity" test is not conclusive, unless the resistance is essentially infinite (blown heater).
If you want a definitive test, you can apply 6.3 V DC through an ammeter, since the current at 6.3 V is defined on the datasheet.
(That would be safer if you use a lab supply with an adjustable current limit.)
On your earlier radio repair, the heaters were in series.
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Thank you Tim. I do have a bench DC power supply where I can limit the voltage and the current so I will try that!
- Wil