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From: rjr@mgweed.UUCP (Bob Roehrig)
Newsgroups: net.ham-radio
Subject: ARRL propagation forecast bulletin nr 29
Message-ID: <10881@mgweed.UUCP>
Date: Tue, 17-Jul-84 18:43:28 EDT
Article-I.D.: mgweed.10881
Posted: Tue Jul 17 18:43:28 1984
Date-Received: Wed, 18-Jul-84 03:31:21 EDT
Organization: AT&T Consumer Products - Montgomery Illinois
Lines: 28


qst de k9eui
hr propagation forecast bulletin nr 29   from arrl headquarters
newington ct  july 16, 1984
to all radio amateurs bt

the solar flux resumed its usual downward trend during the past
week,  moving from 101 on july 9 to 89 on the 15th.  this range
is slightly below the  base  value  used  for  the  propagation
charts  in qst for july 9, but not enough to make a significant
difference in midsummer dx conditions.

the state of the earths magnetic field is more  important  than
the  solar  flux  in  determining  the  usefulness  of  our  dx
frequencies in midsummer.  high  geomagnetic  activity  narrows
the  useful rf spectrum and causes erratic fading and increased
distortion  on  voice  signals,  especially  on  high  latitude
circuits.   these  adverse  effects were very marked july 13 to
15.  they will be in evidence often through july,  though  less
than in the days just prior to the issuance of this bulletin.

with the sun moving southward again, dx conditions will improve
gradually over the next six weeks.  the change will become most
obvious in early september.

american sunspot numbers for july 5 through 11 were between  52
and 82 with a mean of 65.7  ar