ad7i (10/07/82)
qst de ad7i hr propagation forecast bulletin nr 40 from arrl headquarters newington ct october 4, 1982 to all radio amateurs bt the solar flux started rising september 19, at 137. except for two brief dips, it continued upward to 218 on october 3. this was the highest flux reading since july 14. as expected, this produced the best propagation on 21 and 28 mhz in at least five months. it also pointed to improved prospects for 50 mhz dx during the next two solar rotations. most likely periods would be october 28 to november 2 and november 25 to 30. more detailed predictions will be given in subsequent bulletins. one of the most severe geomagnetic disturbances of this solar cycle began september 5. a recurrence of this event is likely between october 4 and 7, probably at lower levels than in early september. watch for exceptional transequatorial propagation on the higher hf bands, and possibly on 50 mhz, in this period. when it subsides, there will be good to excellent conditions on all hf bands through the middle of october. the solar flux will be too low for good 50 mhz prospects at this time, but frequencies below 30 mhz will be quite good. the solar flux is expected to be lower during the forecast week, probably dropping to 150 or lower. this should make for good accuracy in the use of the current qst propagation charts. american sunspot numbers for september 23 through 29 were between 96 on the 23rd and 172 on the 29th, for a mean of 132 ar
ad7i@houxo.UUCP (10/04/83)
qst de w1aw hr propagation forecast bulletin nr 40 from arrl headquarters newington ct october 3, 1983 to all radio amateurs bt the solar flux averaged just over 109 in september, the lowest values since late 1947. solar activity was rising after the 20th, the trend continuing into early october. the flux reached 120 on the 2nd, the highest since the middle of august. the solar flux rise reported last week is expected to flatten off in the 120s and start down about the 4th. there will be another low period about the 7th to 20th. a rise expected at the end of october should bring the best overall propagation of the autumn season to date. above average magnetic field activity beginning about october 5, 13, 17, 23 and 28 will cause increased signal absorption and severe fading over periods of one to three days. the muf will tend to peak about october 4, 7, 14, 25 and 29, reaching its high for the month on the last two dates. american sunspot numbers for september 22 through 28 were between 39 and 54 with a mean of 46.7 ar