#223630 - 05/14/11 08:33 PM
Re: Emergency Radio
[Re: KG2V]
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Carpal Tunnel
Registered: 08/03/07
Posts: 3078
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I've always wondered "why doesn't someone make a small protable crystal radio? A diode as a detector, a High Z earplug, a small tuning cap, and a few other part - NEVER NEEDS power, and works with AM radios
Probably because they don't really work, and their performance is easily surpassed using a Ferranti ZN414 Tuned Radio Frequency Circuit Amplifier in a match box circuit. http://www.mds975.co.uk/Content/trfradios.htmlEven then the performance of the ZN414 was pretty woeful compared to superhet designs which are now standard in most AM radios.
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#223662 - 05/15/11 10:00 PM
Re: Emergency Radio
[Re: Am_Fear_Liath_Mor]
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Veteran
Registered: 08/19/03
Posts: 1371
Loc: Queens, New York City
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[quote] ...snip... Probably because they don't really work, ...snip... I don't know - I used to make them as a kid all the time (using a diode detector) and always got 1/2 decent reception
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#223858 - 05/18/11 10:45 PM
Re: Emergency Radio
[Re: MartinFocazio]
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Carpal Tunnel
Registered: 08/03/07
Posts: 3078
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If anyone is interested in listening to SW radio but does not have a SW receiver then this link might be useful. http://sdrspace.com/ListenForFree/tabid/425/language/en-GB/Default.aspxYou can download the SDR radio software and install on your PC, then connect to networked RFspace SDR-IQ or Net-SDR radio receivers etc then listen to a much wider set of SW bands that are commonly available on most SW receiver sets. It is very impressive as the networked SW receivers are at geographical locations all around the world. I think the idea is to tempt you to eventually get your own $500, $1000 or $3500 RFspace SDR receiver. Edit - BTW doe anyone know of a real time morse code translator application that will output text from the beeps from a computer sound card or .wav or mp3 file.
Edited by Am_Fear_Liath_Mor (05/18/11 11:13 PM)
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#223867 - 05/18/11 11:57 PM
Re: Emergency Radio
[Re: Am_Fear_Liath_Mor]
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life is about the journey
Member
Registered: 06/03/05
Posts: 153
Loc: Ohio
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Hi,
Two I know of are CWGet and CWDecoder. They work by interpreting data from sound card input. They are generally meant to work with CW received from a ham radio, that is, feeding ham radio output into the computer sound card input.
Not sure if this will work with audio coming "out" of the sound card.
If you don't have a physical SW Receiver, what probably will work is if you have two PCs/Laptops and fed the output from the SDR receiver machine (line-out) into the computer sound card (line in) with the CW software.
Note, these software packages are often volume sensitive. You usually have to fiddle around to get the volume going into the machine with the CW software just right (usually volume going in need to be very low – as in the just barely audible range). Also, it may not work well if you would try to use the Microphone in as opposed to the line-in. Some sound cards may only have one or the other. Others may only have one sound input port, but the sound card driver may have a software setting that allow it to be used as either a Microphone-In or a Line-In, at any one time
Edited to make a clarification
buckeye
Edited by buckeye (05/18/11 11:59 PM)
_________________________
Education is the best provision for old age. ~Aristotle
I have no interest in or affiliation to any of the products or services I may mention. Should I ever, I will clearly state so.
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#223891 - 05/19/11 03:38 PM
Re: Emergency Radio
[Re: bacpacjac]
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Veteran
Registered: 07/23/08
Posts: 1502
Loc: Mesa, AZ
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I really like our Grundig FR-200. A/C power, battery and crank. It's never let us down in the 6 or 7 years since we got it as a gift. I was REI yesterday and saw a Grundig and bought it based on your short recommendation on here. I got home and realized I didn't get the FR-200 but the super compact am/fm shortwave w/digital display. The MINI400. Did you realize that Grundig is an eton product? Anyway, its about the size of my iPhone, a smidgen wider but thinner. Do you know how hard it is to find a compact radio with external speaker? Pretty hard. I'm going to use it (with headphones) on my long runs were I can't get the radio through my iPhone app (Oo Tunes)
_________________________
Don't just survive. Thrive.
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#223897 - 05/19/11 07:02 PM
Re: Emergency Radio
[Re: comms]
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Member
Registered: 06/17/07
Posts: 110
Loc: Toronto area, Ontario, Canada
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Do you know how hard it is to find a compact radio with external speaker? Pretty hard. You're not kidding. (By external speaker, did you mean a built-in speaker? That's what I mean...) I have been looking for a real compact AM(/FM) radio, the kind that was everywhere 30-40 years ago, and even at RS say 10 years ago (no RS in Canada now). I have a "last resort" Optimus that works perfectly, just it's been beat to hell and I'd prefer a newer one for reliability. I have plenty of larger AM/FM/SW and ham radios, but this is for my backpack. I was pretty interested to hear of that ZN414. Never heard of it before. I used to be quite into AM radio chips, but mostly the superhet types. Anyway, I have a couple of those tiny "matchbox" AM radios, earphone only. One I got in Canada, it is the long-defunct Clairtone brand, probably from '68. The other I got in England, virtually identical electronically, Sinclair brand, '70. They still work, use button cells that last for ages. I always thought they were crystal-based with an audio amp, there's 1 transistor in there IIRC. Unless of course it's not really a transistor and something similar to that ZN414 came out in the late 60s.
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