Satgen107 HF SATS and SOLAR FLUX by GM4IHJ 15th April 91 As the very high level of Solar flux continues to affect HF satellites ,I am collecting a batch of questions which need answering . So here goes:- Solar flux versus Sunspots . What is the connection for those using one or other in their propagation prediction software . Flux Spot No. Flux Spot No. Flux Spot No. Flux Spot No. Flux Spot No. 70 8 140 94 210 166 280 231 350 289 80 22 150 105 220 176 290 239 360 297 90 34 160 115 230 186 300 248 370 305 100 47 170 126 240 195 310 256 380 313 110 59 180 136 250 204 320 265 390 320 120 71 190 147 260 213 330 273 400 328 130 82 200 157 270 222 340 281 410 336 Best source for this data is PA0HIP whose solare bulletins appear on UK packet addressed " 50MC " and titled " Solarinfo day/month" Using my own software as long range satellite sub horizon events occur has been very revealing. I knew from experience that as we went from Winter into Spring our local GM HF propagation Maximum usable frequency dropped rapidly and stayed down till October despite the high solar activity, whilst by contrast the Australian MUF soared as they began to go into their Winter ( our Summer ). Unfortunately this means as my software shows that recent MUFs over Australia have been so high that the 21MHz uplink to RS12 KT never got up through the ionosphere to the satellite until long after dark over Australia. So while propagation was favourable all the rest of the way to Southern Europe , the sat signal never got started until long after the rest of the path to Europe disappeared. PLEASE NOTE these remarks refer only to satellite signal not terrestrial DX. At the European end particularly in GM , MUFs only just support satellite 29MHz propagation ( it should be better for G). So it is no surprise that the only RS12 signals getting into GM have been as follows :- From RS12 as it came north into the Southern Indian Ocean having just left Antarctica. Eg 4Apr 1700 ut sat heard at 66S 304W for several minutes there after, then again at 1841ut from 78S 350W . Next day 5Apr 1544ut 64S 286W and then 1730ut 60S 310W. A pattern which repeated every day (except 11th Apr) up to 12th April , ie all Greyline solar day/night edge stuff . Away from Scotland. Following Pat Gowen's super contact with ZL on 21 March other stations are seeing the same north south paths as GM EG SM0KV/0 got an RS12 QSO with CE3FIP . Books. A modern description of the HF satellite sub horizon propagation situation will be found in the RSGB Space Radio Handbook. For a full description of the terrestrial situation at times of high solar flux, I know no better source than George Jacobs , old but still very clear, ShortWave Propagation Handbook (CQ Technical series , Cowan Publishing USA) . See you at Kelso Rally May 5th . 73 de GM4IHJ @ GB7SAN