Do you speak Chinese?

My Chinese is non existent, but I see AliExpress is selling a multi-band crystal set with a Band II FM stereo radio included for good measure. All the markings appear to be in Chinese, so I cannot tell what they say. The price seems very high.

Crystal receivers

This was one area of radio that fascinated me, although I have not explored it recently. At one time, my ambition was to build a crystal set that covered VLF to over 1 GHz with maximum sensitivity. 

Remember, crystal sets are passive receivers generating all their power from the TX. Some designs use the rectified signals from many stations to bias the detector on or to power a small amplifier.

These days there are fewer English language broadcast stations on short wave.

In my time I have received stations from all over the world, not via relays that can be much nearer. I have heard amateur and commercial stations too.

Most crystal sets can copy about 1mV signals, although I expect optimised systems can receive far weaker signals.

There is a page on my website about these.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/crystal-set-dxing

1923 crystal set

This was crystal set was made by BTH . 

Imagine the thrill in those early days of radio. 

When I retired some years ago I was bought a Gecophone 1920s crystal set that worked.

I had a webpage for the Gecophone on my old website that I must put on my more recent site.

My old website is still there, but the links may not work as this site is not being maintained.

See https://sites.google.com/site/g3xbmqrp3/home/other/gecophone-crystal-set

Crystal set DXing

 

Many years ago I tried making and using a short wave crystal set. It is on my website.  As you can see, it does not cost much to have fun. I had aims of making a crystal set that covered VLF to VHF. Then my stroke scuppered plans!

Short wave radio is changing and there are far fewer English language broadcasters. I was pleasantly surprised by what I could hear back then. It is not just broadcast stations you can hear.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/crystal-set-dxing .

Crystal Set DXing

Many of us "cut our teeth" by making crystal sets on medium wave to receive a local station. As you know, crystal sets require no power. All you need is a sensitive headset or earpiece as all the power comes from the transmitter.

What is less well known is that a short wave crystal set can be made and great fun had.  This is totally different from conventional SWLing. Signals have to be mV, not uV. It is possible to hear amateur and utility signals as well as broadcast stations. Sadly, there are fewer English language broadcasts to be heard.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/crystal-set-dxing

Time to update the rig?

Wondering about upgrading my rig, but can't get on with these new fangled things, HI. 

DX crystal set

This is a circuit I have never built. It was in QST some years ago and uses a zero bias MOSFET to give better sensitivity. You may want to have a go. Please read the ARRL article below.

See http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

DXing with a twist

One facet of HF radio that you may want to try for fun is DXing with a crystal set where all the power comes from the TX. 

Although you are most likely to hear broadcast stations, you may also copy amateurs. These days it is harder as most speech is on SSB, so you can only copy the muffled sound of envelope detection, but I have copied AM amateurs on 160m. For envelope detection, you may need a "proper" RX to identify the signal.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/crystal-set-dxing .

Crystal set DXing

Many years ago I tried this. Most reception was of HF broadcast stations, but, surprisingly, some amateur stations too. I am sure, with some serious designs, plenty could be copied from VLF to VHF with a crystal set. 

As signals have to be very strong, low level interference is unlikely to be a limitation. It was all fun and a different sort of challenge.

Remember, all the power comes from the broadcaster, unless you find a way of harvesting power from other broadcasters. Certainly, nothing comes from the receiving end!

These days there are far fewer English language broadcast stations on HF.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/crystal-set-dxing .

Crystal set DXing

It is some years since I last tried this, but it was fun. 

Although it is possible to envelope detect amateur stations if strong enough, identifying amateur SSB stations can be quite hard. The first amateur stations copied were on 160m AM way back in the 1960s.  Since then I have copied amateur SSB stations on 80m at some distance. Signals need to be S9++. 

In a crystal set all the power is from the TX end, with nothing at the RX end. No batteries, nothing.

I have seen broadcast signals from all over the world and these were genuine in original country broadcasts, not via relays.  These days there are fewer English language broadcasters as more and more people move to the Internet. 

The circuit shown here is capable of hearing this DX even though it is ultra-simple. For the detector I used a germanium diode, but a hot carrier diode might be suitable. The secret is choosing a diode with a very low turn-on voltage. Silicon diodes are not suitable.

I am sure there will be better circuits around.

See https://sites.google.com/site/g3xbmqrp3/hf/crystalset .

See also http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

Gecophone crystal set

When I retired in 2008 I was bought a Gecophone crystal set as a leaving present. This is almost 100 years old and still works.

It is in a polished wooden case and looks magnificent. They don't make things like this nowadays.

See https://sites.google.com/site/g3xbmqrp3/hf/gecophone

Crystal sets

Some years ago I tried my hand at crystal set DXing on HF. Results surprised me. I was even able to envelope detect some SSB amateur signals on 80m. 

Broadcast stations from their originating countries (many use relays) were copied including Australia and India. The only power is that from the TX with no batteries or other source of energy at the RX.

See https://sites.google.com/site/g3xbmqrp3/hf/crystalset

See also http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

ARRL website - high sensitivity crystal set

The ARRL website has much to commend it, including this article that was in QST some years ago on a high sensitivity crystal set using a zero bias MOSFET.

There is more about crystal sets on my main website. They are capable of some quite remarkable results.

See http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

Crystal sets

It is some years now since I last played with crystal sets. If you have never tried these I urge you to have a go. These are powered entirely by the received signals, so no batteries or power source of any kind is needed.

Being envelope detectors, they are only really suitable for AM, although I have detected SSB and CW signals on mine in the past. There are even designs for band 2 FM using high-Q circuits and slope detection!

In the past, I have copied all over the world on a short wave crystal set. These were genuine receptions from the originating countries and not from relays nearer home. I have copied several amateur signals on 160 and 80m too.

See https://sites.google.com/site/g3xbmqrp3/hf/crystalset

See also https://crystalradio.net/crystalplans/index.shtml

A better crystal set?

Some years ago QST had a circuit for a better crystal set that used a MOSFET. I have never tried this, but I should. It is supposed to be more sensitive than conventional designs, and uses no batteries.

See http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

DXing with crystal sets

Shortwave broadcasting has changed a lot in recent years as more switch to the internet to get their message across. The internet is lower cost and generally much higher quality.

Having said that you may be amazed just what can be heard on a humble crystal set on HF. A few years ago I had quite a bit of success.

There are bigger schematics and photos on the webpage below. Remember all the power comes from the TX end.

See https://sites.google.com/site/g3xbmqrp3/hf/crystalset

MW broadcasters going?

Several broadcasters are leaving MW, instead concentrating on FM, DAB or the internet. The latest reported via Southgate News is a Belgian broadcaster on 621kHz.

This will eventually free up spectrum, perhaps for amateurs (?), but it also means the end of reception on extremely simple receivers like crystal sets.

I well remember falling asleep listening on my crystal set.

A high sensitivity MOSFET crystal set

Firstly, I should say I have not built this, but it looks interesting.

See http://www.arrl.org/files/file/Technology/tis/info/pdf/culter.pdf

Crystals sets

A great deal of fun can be had with the simplest of receivers. I had some great fun DXing with a shortwave crystal set. These days, there are fewer SW broadcasters sending in English, so IDing is harder, but not impossible.

See https://sites.google.com/site/g3xbmqrp3/hf/crystalset

DXing with crystal sets

OK, a confession: it is a long time since I last listened with a shortwave crystal set.

One thing is certain: at the right time it is possible to hear true worldwide DX, and not via relays.

These days there are fewer English language SW broadcasters and it is much tougher. We are also in a period of declining solar activity, so fewer HF bands are open and these stay open for less time. Nonetheless, crystal sets are easy to make and require no power. DXing with crystal sets is a fun activity.

One of my many planned projects is a multi-band crystal set capable of covering from VLF to VHF. It may never get made, but this would be fun.

See https://sites.google.com/site/g3xbmqrp3/hf/crystalset .