My impoved mystery crystal set by G0CWA

[W4HAY]

...Applying a bias voltage to them works well but that is definately cheating...

Even if you derive the voltage from lemons, strips of copper, and iron nails?

Some have used a second set tuned to a nearby "blowtorch" to derive the bias voltage.

[AF6LJ]

Sue, if you'd like, I can drop a microwave diode in the mail to you. I've gotten much better results with them than the 1N34A.

I have everything else save for the earphone and I know where to get that.
Sure

A nd yes...
I know not to check it with an ohmmeter.

[K1ZJH]

As a point of interest, the old microwave diodes in the ceramic cases dating back to WW11
are silicon devices.

I'm not convinced adding bias is "cheating." Carborundum detector assemblies included
a battery and rheostat for optimizing the detector.

Pete

[G0CWA]

Neat idea! Now we wanna see the back of the set.

A full write up is on http://makearadio.com/visitors/nick-mystery.php including photo's Good luck Sue

73 and by for now Nick G0CWA

[W4HAY]

I noticed that link after it was too late to edit my post. Black and blue text are difficult for my eyes to differentiate between on this old Trinitron monitor.

Sue, these diodes show a Vf of about 0.28 Volts. The one I'm sending picked up a couple of signals in the 41 Meter band on my "Tuggle Tuner" set.

[G0CWA]

I noticed that link after it was too late to edit my post. Black and blue text are difficult for my eyes to differentiate between on this old Trinitron monitor.

No problem I understand I was in the same position until I descided to udate my monitor

73 de Nick G0CWA

[KO6WB]

There have been quite a few experiementers that have reported better results with the Galena and cat whisker setup than any commerical diode. I'm not sure that's true and the Galena approach can be a pain at times. As for applying bias from lemon juice, rusty nails or another crystal set I would guess that's fine as long as you are experimenting. Even in that aspect using a battery would be okay, it's just not a straight detection method. For a crystal set adding an amplifier to bring the audio up is defeating the purpose of a simple unit but it is fun to do.
Just have fun
73
Gary

[W4HAY]

There's another little trick that lets you copy CW. Place an oscillator near the crystal set and tune it to the frequencies of interest. A signal generator fed into a solenoid or spiderweb loop for coupling works well. It's effectively a BFO and I've copied very strong signals on 80 and 40 by doing this.

I discovered this after I'd built a tone-modulated oscillator for the BC band to calibrate my sets. I had the tone turned off and as I swept near the frequency the crystal set was tuned to, I heard numerous faint hetrodynes, each corresponding to a BC station. It seemed to work best with the oscillator placed a foot or more from the crystal set. The oscillator was written up in the September '05 XTAL Set Newsletter.

[AF6LJ]

Sue, if you'd like, I can drop a microwave diode in the mail to you. I've gotten much better results with them than the 1N34A.

Thank you the diode showed up in the mail this morning.
Happy
Happy

[G0CWA]

Hi Sue

How's the set going?

Nick