Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [mf]

Medium Frequency: The frequency range from 300 kHz to 3 MHz

Medium frequency is lower than , and higher than in frequency. The common AM radio broadcast band falls within the MF band.

Jump to Frequency Bands: | Band | Frequencies | Wavelengths | | ---- | ----------- | ----------- | | | 3-30 Hz | 10,000-100,000km | | | 30-300 Hz | 1,000-10,000 km | | | 300-3000 Hz | 100-1,000 km | | | 3-30 kHz | 10-100 km | | | 30-300 kHz | 1-10 km | | | 300 kHz-3 MHz | 100-1,000 m | | | 3-30 MHz | 10-100 m | | | 30-300 MHz | 1-10 m | | | 300-3,000 MHz | 10-100 cm | | | 3-30 GHz | 1-10cm | | | 30-300 GHz | 1-10 mm |

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How can I do direct digital synthesis of a 630m WSPR signal?

I want to do direct digital synthesis of a 630m band WSPR signal. Specifically I'd like to use an Atmega 328 chip running at 20 MHz to produce such a signal. I will use standard phase accumulator algorithm which I believe I can get to run in less…
Eric Urban
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MF band mixer - feasible parameters

Trying to build an homebrew receiver for MF band broadcast (Navtext). Usually working on VHF, where all parts are easily found as an IC, but here I'm trying to get back to roots, so I may be missing something. I'm considering a superhet schema and…
gusto2
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How should two loopstick antennas be placed w.r.t each other to maximize transmission?

An engineer working in the RF industry told me something which left me very confused: He said that a pair of emitter-receiver beacons get the clearest signal when loopstick antennas in the receiver and the emitter are parallel. That is, when both…
Dugas
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What are the technical reasons that there are no FM transmissions on the long, medium, or shortwave?

Why are there no frequency modulated broadcasts on the long/medium/short wave, but only on VHF? I'm sure there are many historical and political reasons (long/medium/short wave were already in use for AM when FM radio was developed, VHF still had…
JanKanis
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Commercial Loopstick Antenna Manufacturers?

I am an electrical engineer working on a product that needs a loopstick antenna. I had thought that AM radios were so commoditized that I'd be able to find an off-the-shelf vendor. However the closest thing I found was a recommendation in silicon…
Aaron
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Can one send data over Short-wave frequencies?

I have an inkling of an idea- a modem system communicating over Short-wave. I know that WiMAX already exists, but the difference is that, while WiMAX works on the Gigahertz frequencies, and most concepts for Ham Radio ones think Megahertz…
Rory Yammomoto
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Why is QRN so bad on the low HF and MF bands?

If one tunes an HF/MF radio at night, the lower the frequency (or the longer the wavelength) of the band, the more QRN (static and atmospheric noise) there is. 80m is noisier than 40m, and 160m is noisier than 80m. (I haven't operated on the…
rclocher3
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Supershield or Superscreen coax: Does it exist? What is its common name?

I'm sure this seems like a Google question, but I've BTDT and come up empty. The problem I'm trying to solve is to obtain cables that are as "leak proof" as possible. Tried Pasternak "100% shield" and they leak like a sieve. Tried Andrew FSJ1-50…
user103218
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Ferrite unun transformer to match antenna resistance loads of <50Ω?

For LF/MF (2200m/630m), I am interested in the situation of a vertical antenna with capacitance hat top-loading, where the vertical antenna is VERY short compared to wavelength, and the antenna is brought to resonance across operational frequencies…
photosynthesis
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How much field strength to blow out a receiver?

I was wondering what calculations would need to be performed to find out if a receiver will blow out in the given conditions. Portable AM receiver with ferrite rod antenna 200 ft away from MW antenna producing 1kW RMS into 1/4 wave GP antenna. I…
Synaps3
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Receiving medium - low frequency CPU signal

I'm trying to listen to the CPU freq's my PC produces (kinda similar to what was done here: https://github.com/fulldecent/system-bus-radio) I do see a clear signal that comes from the CPU (I know that because I can control it by reading memory…
George Lashenko
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Utility pit MW/LW omnidirectional antenna

I am looking at antennas for a rather unusual application: mounted under a utility pit lid (manhole cover). The goal is to receive commercial MW/LW stations. The antenna has to be attached to the underside of the lid with a magnet. To make it easy…
user1211
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