Hello everyone, today my uncle brought down with him from Michigan where he lives an old Crystal kit Radio that he and his uncle (who passed away back in the late 1970s) had built together shortly before he passed away, and I'm trying to see if I can get it going for him again, it has what appears to be an old Germaniun signal diode in the radio's circuit (that acts as the "crystal" in the circuit) and the diode is unfortunately dead, and also I can't seem to figure out how the set is supposed to get power (what type of battery and what the voltage should be.)

If any of you guys recognize the radio design (if it was a design from something like an old Radio Shack magazine or some other electronics magazine from that time period) then it would be much appreciated if you could share any information with me about how this radio is supposed to work and what kinds of signal diodes could be used in this radio and what I could used as a power source if one is needed.

See Pictures below.

No battery needed. You just need a good ground, RF from an antenna, and high impedance headphones or an earphone. Those are the 4 connections it has. Power is from the rectified RF. And of course replace the bad diode if it is indeed bad.

No battery needed. You just need a good ground, RF from an antenna, and high impedance headphones or an earphone. Those are the 4 connections it has. Power is from the rectified RF. And of course replace the bad diode if it is indeed bad.

OK, thanks. What kind of diode should I use in this thing? The original one looked like an old Germanium signal diode, like what is used in old TVs and Radios.

Yep, a germanium diode. They rectify as low as .2 Volts. (Compared to silicon .6V)

Simple Boy Scout radio and improvements:

https://m.youtube.com/watch?v=mubvsqFrE88

jr

Yep, a germanium diode. They rectify as low as .2 Volts. (Compared to silicon .6V)

I think I might have some diodes that might work in this radio, but I'm not sure.

I just looked over at AES and they had 6 signal diodes listed there for sale, 3 of them of the Germanium variety (1N34A, 1N60, and 1N270) and 3 of the Silicon variety (1N4148A, 1N914, and 1N4448) and I'm curious as to which one of those would work best in this application, also I'm wondering where I might find some high impedance headphones like what this would use, or if this might even work with a high impedance speaker like the type used on the old 1920s radios used?

I would go with Germanium, or low voltage Shottkey diodes. You want the lowest forward voltage drop diodes you can get.

I would go with Germanium, or low voltage Shottkey diodes. You want the lowest forward voltage drop diodes you can get.

OK, so I'll order a few of the 1N34A, 1N60 and 1N270 Germanium diodes, and see which ones work best, and also try some 1N5158 and BAT41 Schottkey Diodes as well (they're only 10 to 15 cents a piece so they won't break the bank to buy about 10 or so of each type.) :thmbsp:

“I'm wondering where I might find some high impedance headphones like what this would use“
High impedance earphone :
https://www.tubesandmore.com/products/radio_antique_equipment_parts_0?filters=972a919c91 3a972

jr

No battery needed. You just need a good ground, RF from an antenna, and high impedance headphones or an earphone. Those are the 4 connections it has. Power is from the rectified RF. And of course replace the bad diode if it is indeed bad.

Crystal sets require a very strong signal, otherwise you will not hear anything. (I've had several and every one of them only received one station, a 500-watt local station about two miles away from where I lived at the time.) I don't know if the OP is near any very strong radio stations in northern Indiana, but if not, the radio absolutely will not work. Northern Indiana is close to Chicago, which has many 50kW AM radio stations, but I don't know just exactly how strong any of those stations would be in that section of Indiana. The crystal radio might work in the immediate Chicago area, but again, not knowing the geography of the northern Indiana area other than it is within a short distance of Chicago (I live in northeastern Ohio and have never been to Indiana in my life), I don't know how strong those stations would be where the OP is located.

BTW, I agree with Ed in TX about the diode used in crystal sets to rectify the received signal. If this diode is in fact defective (or installed backwards), of course the radio will not operate at all.

If the diode is installed backwards, the only result should be that the audio signal polarity will be inverted.

Did anyone mention that you need a long wire antenna, like on the order of 30-50 feet?

I also wonder how bad the local interference will be these days from fluorescent/LED lamps, other electronic gear, etc. Not sure how different the long wire antenna interference pickup will be compared to a regular AM radio.

As to recognizing the design, it is the very simplest possible crystal radio. As pointed out, it will only pick up strong local stations. If you look on the net you will find many variants, some of which are pretty sensitive. I built quite a few crystals sets and some of the more sophisticated designs work pretty well.

I can get WLS from Chicago in where I live, during the day and During the Night, I can also get WOWO out of Fort Wayne, Indiana where I live, I can also get WLW out of Cincinatti, Ohio really well in the evening and fairly well during the day, and I can get WGN out of Chicago really well during the day and night, as well where I live. Just to give you an idea of the stations I can get in where I live on the AM Dial, all of the Aforementioned stations are 50kW stations.

If the diode is installed backwards, the only result should be that the audio signal polarity will be inverted.

Did anyone mention that you need a long wire antenna, like on the order of 30-50 feet?

I have 3 top-hat style germanium signal diodes that according to my diode check on my DMM are still good, but I have no idea how to tell which way is the anode and which way is the cathode (they aren't marked.)

Did anyone mention that you need a long wire antenna, like on the order of 30-50 feet?I used to use the aluminum window frame in my bedroom for an antenna. Worked great! Growing up in a house within a few miles of AM transmitters at 1080, 1310 ans 1480 kHz I could pick up all 3 stations mixed together at the same time. Simple crystal sets are not very selective.

There have been reports of houses within a mile or two of 50 kW stations producing program sound in the heating ducts - not sure how loud or even how factual this was, but it's a neat urban legend, at least.

Check out this guy's crystal DXing setup:eek:..

https://www.youtube.com/watch?v=Bw4IiTR3Tqw

If you are a reasonable distance from a high power station you can take the rectified audio from one crystal set and use it to power a transistor on a regenerative reciever (and or an RF amp stage or AF amp stage) and get increased sensitivity, selectivity and audio output power in the second tuner.

I've heard of successful FM crystal radios using slope detection of the FM signal too (probably very rare beasts I'd imagine).

There have been reports of houses within a mile or two of 50 kW stations producing program sound in the heating ducts - not sure how loud or even how factual this was, but it's a neat urban legend, at least.

It's not just urban legend. I have read of people within a short distance of powerful AM radio stations receiving the signals on, believe it or not, the burner coils of electric stoves. I guess if the signal is strong enough, just about anything can receive it and be heard. There have even been reports of people receiving very strong AM radio signals on tooth fillings or braces, again if the signal is strong enough (50kW), and if the person is close enough (within perhaps 500 feet or so) to the station's tower(s).

In the early 1970s, I lived just about a third of a mile from a local FM station. I could see the transmitter tower from my bedroom window (I lived on the top floor of a three-story house at the time), and the signal came in like gangbusters. I was hearing the signal between stations on all my FM radios, as well as on channel 6 of an old color TV I owned and even, to my dumbfounded surprise, on the 10-meter amateur band on an old Hallicrafters amateur communications receiver in my Novice class amateur radio station at the time. The station's signal was so strong (and I was only within almost literally a stone's throw from the tower) that it was overloading (!) the receiver's front end.

There is a 1000-watt AM station near my apartment where I live today which, thankfully, doesn't cause me any trouble from strong signals (I am perhaps one or two miles from the station's tower), but I can imagine folks living a lot closer to that station's towers being able to hear it between stations and even, like my experience with the FM station where I formerly lived, hearing it on stove burners and even, if the person lived extremely close (within a few hundred feet or less(!)) to the towers, on bedsprings.

BTW, I no longer live anywhere near that radio station which was taking over my FM radios in the 1970s (thank goodness!); in fact, several years ago (in the 1980s, IIRC) the radio station itself was moved to another town a few miles away, and I now personally live in a very small town some 20 miles from the city to which that station is licensed.

However, you can be sure I will never forget the experiences I had when I lived literally in the shadow (!) of that station's tower. One of the other places in the Cleveland area where this kind of thing can happen is the city of Parma, Ohio, west of Cleveland, where many if not most of Cleveland's AM and FM radio stations' towers are located. Most of the AM stations are 50kW flamethrowers, with the FM stations having ERPs in the tens of thousands (!) of watts. Again, I am very glad I never lived in that area, and left the city many years ago where that 27.5-kW FM station was giving me more grief than I wanted in the first place; however, I had no choice in the matter when I lived there, as I was 16 years old and was living in that area (Cleveland Heights, Ohio) very much against my will (very, very long story, OT, and something I wish I could forget, but I know darn well I never will).

It's not just urban legend. I have read of people within a short distance of powerful AM radio stations receiving the signals on, believe it or not, the burner coils of electric stoves. I guess if the signal is strong enough, just about anything can receive it and be heard. There have even been reports of people receiving very strong AM radio signals on tooth fillings or braces, again if the signal is strong enough (50kW), and if the person is close enough (within perhaps 500 feet or so) to the station's tower(s).

In the early 1970s, I lived just about a third of a mile from a local FM station. I could see the transmitter tower from my bedroom window (I lived on the top floor of a three-story house at the time), and the signal came in like gangbusters. I was hearing the signal between stations on all my FM radios, as well as on channel 6 of an old color TV I owned and even, to my dumbfounded surprise, on the 10-meter amateur band on an old Hallicrafters amateur communications receiver in my Novice class amateur radio station at the time. The station's signal was so strong (and I was only within almost literally a stone's throw from the tower) that it was overloading (!) the receiver's front end.

There is a 1000-watt AM station near my apartment where I live today which, thankfully, doesn't cause me any trouble from strong signals (I am perhaps one or two miles from the station's tower), but I can imagine folks living a lot closer to that station's towers being able to hear it between stations and even, like my experience with the FM station where I formerly lived, hearing it on stove burners and even, if the person lived extremely close (within a few hundred feet or less(!)) to the towers, on bedsprings.

BTW, I no longer live anywhere near that radio station which was taking over my FM radios in the 1970s (thank goodness!); in fact, several years ago (in the 1980s, IIRC) the radio station itself was moved to another town a few miles away, and I now personally live in a very small town some 20 miles from the city to which that station is licensed.

However, you can be sure I will never forget the experiences I had when I lived literally in the shadow (!) of that station's tower. One of the other places in the Cleveland area where this kind of thing can happen is the city of Parma, Ohio, west of Cleveland, where many if not most of Cleveland's AM and FM radio stations' towers are located. Most of the AM stations are 50kW flamethrowers, with the FM stations having ERPs in the tens of thousands (!) of watts. Again, I am very glad I never lived in that area, and left the city many years ago where that 27.5-kW FM station was giving me more grief than I wanted in the first place; however, I had no choice in the matter when I lived there, as I was 16 years old and was living in that area (Cleveland Heights, Ohio) very much against my will (very, very long story, OT, and something I wish I could forget, but I know darn well I never will).

There's a couple of FM Stations near me that are 50kW Flamethrower Stations that also have many repeaters stations across Indiana, Michiagan and Ohio (going down as far as the Kokomo area of central Indiana most of Southwestern Michigan, the Richmond area of east central Indiana, Southeastern Michigan, and Northwestern Ohio and they are both Contemporary Christian Music stations that also play a lot of Bible Teaching programs throughout the day) which the stations I'm referring to is WFRN that is based out of Elkhart, Indiana (just down the road from where I live) and WBCL out of Fort Wayne, Indiana, and both stations of which have been around since 1970s (the early days of the Jesus Movement in America, which is where the concept of Contemporary Christian Music came from originally.)

And WFRN the first station I mentioned does the same thing that you mentioned that the station you lived near did to you, and that's because the frequency that their station broadcasts at is 104.7 is a "multiple" of the FM IF Frequency of 10.7 MHz so then basically their station comes in on pretty much every spot that is a "multiple" of the FM IF Frequency on a poorly aligned or poorly designed FM Radio.

I used to live across the street from a 5 kW am station. I was about 100 yards from the closest guy wire tiedown. I hooked up a good ground, a wire draped across the street connected to the guy wire as high as I could reach, a tuned circuit, a galena
(PbS)/tungsten-tip diode, and an output transformer. I got excellent volume on
my low efficiency stereo speakers.

It didn't work without a tuned circuit because I was 1/2 mile from
a different 2 kW station. That one produced loud signals on headphones,
but not a speaker.

Just go looking on the web for crystal set schematics. They all orient the same way.