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 .

Crystal set DXing

This is not as easy as it once was as there are fewer English language AM broadcast stations left on the traditional shortwave broadcast bands. Nonetheless, you may be surprised by what you hear.

My best DX on a simple crystal set is Radio Australia (broadcasting from Australia, not via a relay), All India Radio, Cuba and the VOA from Liberia years ago. You can even envelope detect amateur SSB signals although IDing these can be tricky. Remember, all the power is provided by the TX with none required at the RX end.

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

Crystal Sets

It is some years since I last made a crystal set, but I well recall a UK book called "The Boy's Book of Crystal Sets" which I think was first published in 1954. It is available on-line.  At the time "Boy's" was OK. If published now, we'd have to say "Young Person's".

Years back I made a short-wave crystal set and heard some impressive DX with it including Radio Australia and Radio Havana. Both these and many others were NOT more local relays. Radio Australia was a real catch and totally amazed me at the time.

See http://www.vintageradio.me.uk/crystal/boys_book_xtal.htm .

There is also some information on my main website. Crystal sets are easy to make and capable of surprising results.

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

DXing with crystal sets

Yes, it is possible to hear a long way on a crystal set. The equipment needed can be extremely simple too.  What is needed are a good pair of ears and sensitive headphones.   My ears are getting old and if I can hear this DX then younger ears certainly can. I have found a low cost very high impedance crystal earpiece worked well. You may have better headphones?

Copying amateurs, most of whom use SSB, is more difficult. Remember, a simple crystal set is only able to envelope detect, although in the USA 75m AM signals are regularly copied at great range. Some SSB signals on 10m Es should be strong enough to envelope detect. Based on my tests, if stronger than 500uV to 1mV the signals should be copyable. Quite a few signals can be this strong.

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