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| 136 kHz DX |
| Weather forecasting |
| 144 MHz DX by forecasting Auroras |
Get 30 hours notice of auroras, and possible VHF openings in the UK, by monitoring the strength of U.S.A.
VLF signals on 17.8 or 21.4 kHz. During the day look for a solar flare causing a
sudden change (usually an increase) in signal strength of about 6 dB from the usual night time level,
and recovery after about 1 hour.
Get the receiver working on 60 kHz and then retune with additional capacitors,
C2 + 180 pF, C4 + 47 nF, C8 + 47 nF, C9 + 47 nF, C10 + 100 nF.
You can just about hear the USA stations in the UK
with the built-in ferrite rod antenna, but you will need a few metres of external antenna
to detect changes in signal strength.
You will not be intercepting any messages from these U.S. Navy transmitters,
just monitoring the level of their 24 hour/day world wide signals.
You can use this circuit to feed a chart recorder or A/D converter.
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136 kHz DX and Weather Forecasting
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Receive amateurs on the 136 kHz band or receive weather facsimile forecasts on 131.8
kHz (France) or 134.2 kHz (Germany). The modulation is white + 150 Hz, black - 150 Hz.
Get the receiver working on 60 kHz and then retune with capacitors,
C4 470 pF, C7 180pF, C9 2200pF and T4 2N2369 or equivalent high speed transistor.
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For further details and discussions please e-mail.
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