''But G4WGT and G0NBD'', // ''is over hilly, lower conductivity ground.''
Steady on Jim , your 'not' suggesting Gary and myself are 'over the
hill' !!
We did have on the uk500khz site , the beacon plots , that where
produced by Andy and Gary, using the G3PLX software and a Tx
timing cct from Andy (G4JNT)
I think theses are still saved in zip files , or we may still have
them saved, these showed quite nicely the path changes over time and
the noise level variations ,
Quite a change to when 'we' first came on 500 with micro erp levels
and no dedicated software !
Unless you have quite reasonable power levels and antenna systems ,
other than local qso , plain CW is not really a option on 500 ,
luckily with the recent developments, narrow data communications will
be possible for all.
73 -G..
--------------------------------------------------
From: "James Moritz" <[email protected]>
Sent: Sunday, June 17, 2012 9:06 PM
To: <[email protected]>
Subject: LF: Re: Further MF impressions
Dear Stefan, LF Group,
I just thought my receiver isn't working correctly. I thought the xtal
does not start to oscillate due to the higher ambient temperatures in the
afternoon. But later i found that the band noise on MF is significantly
lower than in the evening, at least 20 dB.
As well as the natural band noise being lower at MF (I estimate the noise
FS is about 10dB lower), there is also not the constant presence of
man-made noise, such as Loran and DCF39 sidebands. So the spectrum around
500kHz does sound much quieter, especially during daytime.
What do others know about the ground wave range in summer and in the
afternoon? When does the band open? Similar to LF?
As others have said, broadly similar to LF - sky wave is very weak until
darkness has arrived, so ground wave dominates daytime communication.
Ground wave signal levels seem to depend greatly on the type of ground at
distances more than 100km or so. For example I can easily hear G3KEV
during the daytime here, and the path from Hatfield to Scarborough is
over flat, high-conductivity ground down the east of England. But G4WGT
and G0NBD, and stations in Wales, are extremely weak in daylight at
similar distances, although they are quite strong after dark The ground
path to these stations is over hilly, lower conductivity ground.
Sky wave signals over fairly long distances show very deep fading over
periods of a few minutes - signal levels are usually constantly changing,
and I have often seen variation of over 30dB in one minute on beacon
signals. This can make QSOs difficult, with a signal that was R5 suddenly
disappearing completely and not even visible on the spectrogram. Over very
long distances, trans-atlantic for example, the fading seems less severe
although signals are usually quite weak and propagation is very variable.
For contacts around Europe, I would say 136k actually gives more reliable
signal levels, but for many stations 500k is easier because higher ERP can
be achieved with a small antenna, and noise levels are often lower.
Cheers, Jim Moritz
73 de M0BMU
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