Question about Radio Stations and Bands...

[Dawny]

Hello. Really not sure if this is the right forum for this...

I half expect this question to be beyond the scope of this site and for it to end up in the trash can but in the small hope that someone might be able to answer it I’m going to ask it anyway…

As some of you might have noticed from my other posts I tinker a lot with building radios, Anyway the other night with a home made coil I wound I was picking up a cluster of Radio stations the consisted of an English radio station that seemed to come from China, an English that only spoke about Africa and drowning everything else out was a radio station that was called Voice of America. Now with me being from Australia does anyone happen to know what band (E.G. MW, SW1, SW2, SW?, FM, LW) I might be receiving?

Thanks in advance for any help anyone might be able to give.


Dawn.

 

[HiTech]

VOA is a powerful world-wide broadcaster. There frequencies are numerous and can be looked up here: **broken link removed**


They have broadcasts in 45 languages, AM, FM, SW, television, and Internet!! That's how indepth and large that network is!

 

[audioguru]

MW and SW bounces off the ionosphere at night sometimes. FM is at a frequency too high to go far or bounce.

There are many websites with spec's about making coils and what frequency a certain coil will resonate at when it has a certain parallel capacitor value.

Since one station drowns out everything else then the selectivity of your radio is very poor.

I hope your "radio" is not a super-regen.

 

[JimB]

If the radio you are using to hear these stations is the circuit you showed in the post about using a frequency counter to measure the frequency of a radio, then I am not surprised.

That radio is a simple crystal set with one tuned circuit.
The selectivity will be very poor. (Selectivity = the ability to discriminate between stations on adjacent frequencies.)

THe frequency of the stations you heared is anybodies guess.
If you can give the details of the coil and capacitor, it may be possible to calculate the approximate frequency.

JimB

 

[CheapSlider]

The terms SW1 or SW2 dont have any particular meaning. Some radios will go from SW1 to SW9 but may not cover any more band than another radio with SW1 and SW2.

Some modern radios will tune continuously from 30kHz to 30MHz (or more to GHz). They can vary their bandwidth for receiving different types of signal and use various modes for detection.

There are many web sites devoted to SWL.

Due to the ability to propogate over long distances short wave used to be the only way to get news from overseas (or news from home if you were an ex-pat) .
In the tropics, short waves are still favoured, over broadcast band, due to electric storms.

With modern technology and developements Short Wave Listening comes under the hooby of international or long range (DX) reception. It includes TV as well as voice and other more exotic modes.

DRM is a mode being tried out by some international broadcasters which can give near FM quality over SW.



Satelites have made programme distribution much easier and broadcasters can have local relays in or near their target countries - thats why its possible to get good reception of BBC World Service in places far from London. China Radio International can be easily received in europe courtesy of Albania. Some International broadcasters even use local relays on FM.

WRN distributes International radio services world wide.

VOA operated TV Marti which broadcast to cuba using a tethered ballooon to support aerials 16km (10m) high above Cudjoe Key, Florida. (The aerostats were blown away by a hurricane)

 

[audioguru]

I didn't see the schematic for that crystal "radio" before. The AM detector diode feeds the very low input impedance of the transistor. Then the detected level and selectivity are ruined.

I have never used an AM "radio" that doesn't have automatic-gain-control. Strong close stations will be much louder than weak distant ones.

 

[stevez]

Your post said it was night and if it was several hours after sunset and before sunrise I'd say you can eliminate anything from 15 mHz up based on my listening experience over the summer. That may not be much help but it eliminates some possibilities.

If you were able to occasionally monitor the behavior of signals related to sunrise/sunset you might also be able to determine direction. Here in the northeast US I'll hear broadcast stations from Europe on 40 meters (7 mHz) as late afternoon approaches - it's dark there and beginning to get dark. Those same stations fade as sunrise comes over the Atlantic.

 

[Hero999]

You mean 15MHz and 7MHz, please don't say 7mHz and 15mHz as it's totally incorrect.