12 Jun 2015

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 .

2 comments:

Unknown said...

Hi Roger,
re Crystal sets - I once saw a circuit that used a crystal set fixed tuned to a long wave station, rectified to provide DC to a second tuneable crystal set, with transistor amplification powered by the rectified DC.

Do you reckon you could get enough power from a quartz crystal by piezo electric effect (i.e tapping it) to make a Crystal Transmitter with no power source?

73 Ken

Roger G3XBM said...

There was once a schematic of a CW TX for 40m that generated the power by keying a large LS coil. When the key went down and up it moved the coil which, when rectified, powered the TX.It produced very low power but worked.

Michael Rainey, in the USA, has done experiments with sound powered voice rigs.

Not sure about your scheme Ken.