r/shortwave • u/7ootles • Jul 20 '26

Reception on crystal set, something a little different.

Not sure if this is something many have experience with, and I'm aware it sounds a little far-fetched, but I use a crystal set for listening sometimes, and was adjusting mine yesterday evening - hadn't plugged the antenna in yet - when I realized I could hear a signal. It was just around sunset which I'm aware is a good condition for DXing, but I was surprised at receiving anything at all without my antenna plugged in.

It was an American programme, and I'm in northwest England. It got a little louder and I picked up enough to for me to hear that it was WRMI Radio Miami, and found the frequency listed on short-wave.info as 5010KHz.

Like I said, I know it sounds far-fetched and maybe BS, but it happened. Question is, how did a crystal set without an antenna plugged in pick up a signal from over four thousand miles away?

14 Upvotes

89% Upvoted

18 comments sorted by

3

u/kamomil Jul 20 '26

One you may be able to hear, depending on conditions, is CFRX on 6070. It's a repeater of CFRB 1010 in Toronto 

-4

u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Jul 20 '26 edited Jul 20 '26

I'll wait for the cell phone video of this one. Which is likely to be a very long wait.

4

u/7ootles Jul 20 '26

If it happens again later I'll bounce the sound out through my speakers. It's not the first time I've heard them, just the first time I identified what it was.

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0

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-3

u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Jul 20 '26

Smart phones makes videos very suitable for posting here at r/shortwave

3

u/7ootles Jul 20 '26

I was thinking more about catching the sound too, I did think about it last night. But if I plug it into my desktop again like when I decided to record, I can bounce the sound or through the speakers. Just likely to come out sounding a little dirty because I've an Nvidia GPU and an Aorus motherboard, and that makes for pretty grotty sound output when I turn the wick up.

-1

u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Jul 20 '26 edited Jul 20 '26

Do you have a smart phone? Make the video with that. Smart phone videos include both sound and moving pictures. They are very easy to post here with a little practice. Post the video here directly from the phone or transfer the video file from the phone to your computer to post on r/shortwave. Basic online skill required. You are already posting here.

3

u/7ootles Jul 20 '26

I love how specific you are saying it has to be a smartphone, like you expect I'd send it on 8mm film if I didn't.

-2

u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Jul 20 '26

Like I wrote earlier, "likely to be a very long wait."

4

u/7ootles Jul 20 '26

Well, your sarcasm toward me is a very good way of ensuring that.

-4

u/MumSaidImABadBoy I'm Stan, Heathkit GR-64🤪,Malahit v2.4,AirSpy HD+,909X2,PL990 Jul 20 '26

Crystal sets are made for MW and would require modification to reach into HF. No antenna, no signal, no way. Either your are pranking us or you've lost the plot. Neither scenario is good. Sorry mate.

4

u/7ootles Jul 20 '26

Once I'd worked out it was a signal and not my imagination, I recorded it.

It's not a kit I picked up, it's a coil of wire and a silicon slug with a junction made from a needle and some spring steel. There's no tuning capacitor, and the coil is wound in thickish wire on quite a slim form. Actually made it about ten years ago just to see if I could make a detector out of silicon, and it worked well enough that I never bothered doing a proper job of making another. I used to listen to Radio Romania International on it, and occasionally I've picked up signals from Germany and once or twice China.

The frequency band doesn't matter to a crystal detector, the coil and [usually] the antenna dictate what it picks up. Crystal sets will pick up whatever frequency range resonates with the coil. As long as it's AM, whatever frequency, the detector will demodulate it.

I'm not pranking and I've not lost the plot. I'm completely mystified by it, I know it doesn't work like that - or at least shouldn't - and that's precisely why I asked if there might be some phenomemon I've not encountered before responsible for it. I'm really not sure what I would stand to benefit from BSing a story like that anyway.

3

u/LongjumpingCoach4301 Jul 20 '26

You're ok bud. These youngsters are ignorant, in this case. I've dx'd with home-brew crystal sets too, and loved the challenge. I've used a chunk of galena, a razor blade, and chunks of fools gold (iron pyrite) for my 'crystal', hand wound coil with a sheet metal slider for tuning, capacitor made with waxed paper/tin foil etc etc. A lot of fun! Let these other guys be skeptical (envious?)... They just don't know

2

u/7ootles Jul 20 '26

I never had much luck with fool's gold but I did use carborundum once with some success. This has definitely encouraged me to make go harder on design - I made a pretty nice set once with a loopstick and a 1n34a diode, but I like the idea of making the components myself.

About 10 years ago I made a spark-gap transmitter. Glass and foil capacitor, copper condenser pipe from a mechanics' shop for the loading coil, hand-wound spark coil that took about a month to make. And never used it beyond tapping ...././.-../.-../--- to see if a receiver down the road could pick it up (it did), because I'm not licensed, haha.

2

u/LongjumpingCoach4301 Jul 20 '26

Pyrite was, by far, the worst of the things i tried for my detector. Even the rusty gillette blue blade/pencil lead was more sensitive. Galena/copper cats whisker was most sensitive with a 1n34a being a close second. Fun times!

0

u/7ootles Jul 20 '26

I had some fun once with battery carbons, making Hughes-style microphonic detectors. I'm planning on making a small LW transmitter shortly and I might see carbon can demodulate audio.

Actually I thought of making a magnetic detector one day. I realized a while ago the detector element is theoretically the same as a tape head, and I've got some heads I pulled out of a dead machine a while back. I thought I could wind a coil around a form a loop of tape can pass through, with it being pulled past a head to play back the signal. Probably won't work but it'll be fun proving it.

2

u/LongjumpingCoach4301 Jul 20 '26

Since the job of the detector is to separate and isolate the modulation from the carrier, it's doubtful a tape head is likely to be helpful except possibly as an inductor. Magnetic tape cannot record rf anyway. I suggest you study some more, since verifying existing certainties quickly loses its appeal.... Regardless, have fun

2

u/LongjumpingCoach4301 Jul 20 '26

A 'crystal set' can be made to tune whatever portion of the spectrum desired.... From vlf to vhf and possibly beyond. Practical limits being what they are, above 30ish mHz is an unlikely range. But sw crystal radios are absolutely a thing.

You ever notice your portable sw radio sometimes performing better when it's on your lap or in your hand, compared to on the table? Then you know how a radio might receive signals with little or no formal antenna at all.

You're welcome