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cookiejar
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Old Electronics
cookiejar   11/15/2013 3:14:27 PM
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About 50 years ago, an old friend asked me about getting his old radios going.  They were obviously the Rolls Royces of their day.  Huge multi-ganged capacitors, 12" electromagnetic speakers.  The speaker's magnetizaton winding was used as a choke in the power supply.  There were separate chassis for the power supply and audio amplifier.  All very impressive.  One actually worked  with a very unpleasant sound from the disintegrated paper cone.  Moving any of the wiring resulted in bare conductors, the insulation was so brittle.  In those days before the Internet I couldn't find replacement tubes or speakers.  So I politely passed on the request to repair the beauties.  I believe they were trashed.

Today, all of my over 50 year old Heathkit tube equipment still works, when called upon a couple of times a year!  My EICO tube stuff has all packed it in decades ago (transformers).  You can still get all the tubes and most components you may need off the Internet today, though I've never had the need.

My 1969 vintage Quad electrostatic speakers and solid state preamp and amp are still in daily use, still supplying the best sound I've heard for 42 years.  I cannot believe how poor the quality is of current production speakers in comparison.  If need be, the discrete components used in this equipment are still readily available.  My only addition to our audio system was a Sony 15" sub-woofer that I got for $200 on clearance 5 years ago.

Any recent electronics with its custom ICs becomes unserviceable in very few years.  Many is the time I've requested a part from a reputable manufacturer only to be told that service parts are no longer available after only 5 years.

I certainly have no room in our house for all the pieces of unrepairable electronics I've been offered.  The real thrill is having an antique that works like new.



BobsView
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Nice Design
BobsView   11/15/2013 3:00:22 PM
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Since household radios of that era tended to be large and bulky, this looks like a first attempt at miniaturization. And what a fine example it is.  It's unbelievably small by the standards of the time and the internals are well protected by the wooden box.

The electrical design also appears to be well thought out.  From the three-section tuning capacitor, it appears to have a tuned RF amplifier on the front end.  Generally one section was for the Local Oscillator, one for the Mixer and the one for the Antenna input.  Later radios eliminated the RF amplifier resulting in less sensitivity and selectivity.

I didn't see a speaker so this was probably designed to be used with headphone, fairly common during those days.  I have to wonder if they offered an optional amplifier and speaker like the i-phone does these days.  The more things change...

When I was a pre-teen, I would inherit radios similar to this one from neighbors that were upgrading to house-powered units.  Batteries were always the issue.  They were expensive and didn't last very long.  I soon figured out how to make my own power supplies that could run off the mains.

 It's interesting to analyze the design to see how the engineers of the day were able to use their imagination to overcome lack of materials, components, and technology and end up with a pretty capable performer.

If someone had the inclination to trace it out, I would really like to see the schematic.

 

Ucster
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Rookie
Thanks for sharing
Ucster   11/15/2013 2:22:31 PM
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Thanks for sharing your Radiola 16.  I have a house full of old radios, it's an affliction that I've had for several years.  There is no known cure.

A lot of the metal used in these old sets was "pot metal" which is known to "grow" or creep.  Tuning condensers and pulleys, etc. are negatively affected by that.  The tube in image 13 appears to be equipped with an "anti microphonic" device. Audio output tubes were famous for microphonics and there were various cushions, sockets, and rubber covers available to cut down on howling tubes.

Best wishes with your radio.  It's very important to remember where we've been.

David

AA9UC

Crusty1
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CEO
Re: Old electronics
Crusty1   11/15/2013 12:29:07 PM
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@David : As a watch and clock repairer I never use WD40 on bearing surfaces it dries out and increases friction. Better to use Three in One oil, it gets in to joints frees and polishes. Mind you friction on that variable capacitor would not cause a lot of problem. Like you, I found some of the dial cords could be a big pain to replace

David Ashton
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Re: Old electronics
David Ashton   11/15/2013 12:25:03 PM
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@Grover....I will admit it's not the prettiest old radio I have seen.... but people from that era would probably say the same about our stuff.

Especially if it could be got working, I wouldn't mind having it around...  but then I'm just an old fart and you look like you're still a spring chicken :-)

David Ashton
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Re: Old electronics
David Ashton   11/15/2013 12:20:15 PM
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@Caleb - it looked like steel or metal of some sort was used for the dial cord - if so and if you can free that capacitor (WD40?) it should not take much more to get it going.  Otherwise you'll have a job renewing the dial cord - I used to do a lot of them when I was younger and some of them can be real sods to get right.

Crusty1
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CEO
Re: Schematic Courtesy the Museum of Broadcasting
Crusty1   11/15/2013 12:01:43 PM
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@Bert22306 : And the really odd thing is the volume control. It operates on the voltage appplied to the *heaters* of the RF amps. How weird is that?.

My Dad was an army radio operator on the North West Frontier of India, way before WWII.

I seem to remember he told me that a lot of houses of this era did not have an electricity supply.  So the sets were powered by a 2 Volt wet lead acid accumulator, a dry cell grid bias battery tapped at 4.5 volts to 9 volts and a dry cell HT battery with tappings at 120 v Dc  to about 200 V DC. The grid bias battery and the HT battery lasted a fair time, but the big drain was on the heater battery.

As you had to lug the battery down to a charging point, which in England was usually a bicycle and radio repair shop and pay for it to be recharged. it made great sense to reduce the current taken by the heaters and thus put off recharging the battery for a bit longer.


If anyone can confirm this, it means I did learn something about valves from my Dad, even though I quickly moved to the germanium transistor, as soon as it became available on the DIY market.

MeasurementBlues
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Re: Old electronics
MeasurementBlues   11/15/2013 11:48:39 AM
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Like old electronics, especially audio? Take a look at the sidebar at the bollom of this page.

Testing the pro's audio

 

MeasurementBlues
User Rank
Blogger
What's left of RCA
MeasurementBlues   11/15/2013 10:50:30 AM
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Not much other than a name. rca.com doesn't even have contact info, much like another name that exists only in a name: Westinghouse. I'm convinced that the names are owned by Chinese companies who use the name for the name's sake.

Case in point: my father-in-law has decided to replace his tube TV with a flat screen. He immediately gravatated to RCE because to him, RCE is symonymous with quality. I told him not to bother, it's just name now, bought by a company because there are people do relate to the RCA name.

MeasurementBlues
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Blogger
Re: Old electronics
MeasurementBlues   11/15/2013 10:44:41 AM
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If only I still had my father's Zenith Trans Oceanic. What a supurb AM/SW radio. I used it to pull in distance AM stations when I was in high school.

I don't know what happened to the Zenith. Maybe I gave it away when I cleaned out his house.

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