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| To: | "LF-Group" <[email protected]> |
|---|---|
| Subject: | LF: SAQ |
| From: | "Dick Rollema" <[email protected]> |
| Date: | Sun, 30 Jun 2002 16:40:51 +0200 |
| Cc: | "Cas Caspers" <[email protected]>, "Jaap Kroon, PA0IF" <[email protected]>, "Jan Harte" <[email protected]>, "Jan Hekkert, PA3HCD" <[email protected]>, "Koos Fockens, PA0KDF" <[email protected]> |
| Reply-to: | [email protected] |
| Sender: | <[email protected]> |
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To All from PA0SE Today I had good reception of SAQ on 17.2kHz. I used a Wandel & Goltermann SLM type SPM-12 connected to the aerial system for 136kHz with 26nF extra in parallel with the loading coil. Replacing the aerial by a one-turn untuned square loop of 1 x 1 m the signal was sufficiently over the noise to be measured at 0.174 microvolt (25Hz I.F. bandwidth). From this follows a field strength of about 482 microvolt/metre (53.7dBµV). This makes it possible to do some speculation as to the power radiated by SAQ (Effective Monopole Radiated Power, EMRP). The coordinates of SAQ are given as 57.07N, 12.24E. Using a computer program written by Harry, PA0LQ, I find as QTH locator JO67CB. My own locator is JO22GD. Again using Harry's program yields a distance of 735km. We can now enter these data into the graphs of CCIR Recommendation 368-7 for ground-wave propagation. This results in: Type of ground dielectric constant conductivity (mS/m) EMRP Perfect ground - - 1.4kW Land 40 30 3.0kW Land 22 3 3.7kW Medium dry 15 1 4.7kW ground Dry ground 7 0.3 5.9kW ground If we estimate from these data an EMRP of 4kW then with an alternator output of 200kW the efficiency of the aerial system is (4/200) * 100% = 2%. For an aerial at such a low frequency that seems not too bad. It could well be that the aerial system was designed to give some directivity towards the USA. In that case the power must be higher than assumed. Well, take it for what it is worth! It would be nice if someone nearer to Grimeton would measure the field strength outside the near field area, for instance at 5 wavelength distance, or 87km. At that distance at 17.2km perfect ground can be assumed for calculating the EMRP (1kw produces 300mV/m at 1km distance, decreasing in a linear way with distance). I also managed to work SA6Q in the 136kHz band. Sent RST459, received RST429. I have made a WAV recording of SAQ of 1 minute duration and have sent it to SAQ. It is much too to pass the reflector. 73, Dick, PA0SE |
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