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Electronics Forum / Basics / March 2006Crystal Radio Pre-Amp
Is that what you would call a device that takes the signal directly from the antenna before passing it on the the rest of the circuit? My little one (11 years old) recently built a crystal radio but even with my long wire antenna from my shortwave radio the signal is weak. Also the kit does not have any ground and from what I remember from years ago that these types of radios have to be grounded? No reference to grounding it at all with the instructions? The kit consists of a variable capacitor, diode and a couple of coupling capacitors. It has a pre-wound "AM Inductor", everything is correctly installed and there was no poor soldering? Can anyone point me to a amplifier that I could put before everything in the circuit? Thanks JimD > Is that what you would call a device that takes the signal directly from > the antenna before passing it on the the rest of the circuit? [quoted text clipped - 16 lines] > > JimD ground it..  SignatureReal Programmers Do things like this. http://webpages.charter.net/jamie_5 > ground it.. Exactly. Must be the lawyers. >> ground it.. And if that doesn't do it try going here http://www.techlib.com/electronics/crystal.html Also go to Google and search for crystal radio amplifier. Mike > Is that what you would call a device that takes the signal directly from > the antenna before passing it on the the rest of the circuit? [quoted text clipped - 16 lines] > > JimD Before you go looking for an amplifier, ground the other end of the coil. How far are you from a radio station? Tom The ARRL Publishes The Radio Amateur Handbook every year. Circuits for RF preamps are in that book. Go to your local library. Or http://www.arrl.org. Raymond Borowiak KC8OJU => My little one (11 years old) recently built a crystal radio but even =>with my long wire antenna from my shortwave radio the signal is weak. ...snipped... My experience with these little marvels many years ago was that one needed a good ground (near a radiator or water pipe seemed to work well) and you needed some relatively high-quality headphones. Hi-impedance units worked better than 3.2- to 8-ohm phones. And the question of transmitter power and distance from the antenna comes into play as well. Don't expect modern communications-receiver performance from a crystal set. The more wire you have in the air the better, also! Is your "crystal" a packaged diode or a hunk of galena on which you have to find the "sweet spot" with your cat's whisker? Oops. I just dated muself! Cheers-- Terry--WB4FXD Edenton, NC Well I'll tell you about my loop I added to my AM radio. I took the railings from a baby bed/crib. Which are about 3' by 5'. I wound 5 turns of wire around the circumference, like 16 feet per turn. I link couple that loop with a smaller loop to my AM radio loop stick. I measured the resonance freaquency with a grid dip meter, resonated at 1050 Khz right in the middle of the AM band. Nice thing about big loops they have all that wire you are talking about packed into a small area. My loop really increased the signal into my AM radio. I heard more stations coming in for sure. There's no grounds for dismissing a loop antenna. Later |
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