LF: Re: Further MF impressions

["Alan Melia" <alan.melia@btinternet.com>]

Stefan, the groundwave does not change, but what you have is varying amounts 
of skywave and daytime "fading" The wavelength is only a quarter of that at 
136kHz so it only tales a quarter of the change in (apparent) reflection 
height to give the same sort of constrctive and destructive interference. 
500kHz does not travel over land so well as the surface "roughness" is 
bigger wrt a wavelength ( but even rough seas are generally less "rough" 
than land ) Yes 500k is an interesting frequency and quite different to both 
136 and top-band. There are times of the day when the fading can be vicious 
at relatively short range  Also with the shorter wavelength most antenna 
height limited stations can have up to 16 times more ERP than at 136kHz
Enjoy the new "playground"  :-))

Alan G3NYK

----- Original Message ----- 
From: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, June 17, 2012 3:03 PM
Subject: LF: Further MF impressions


> MF,
>
> 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. So now i see that the band 
> noise is about 5 dB above my soundcard noise with the current setup.
> What do others know about the ground wave range in summer and in the 
> afternoon? When does the band open? Similar to LF?
> BTW thanks to DF6NM for the grabber. Nice tool to get some experience in 
> these first days...
> 73, Stefan/DK7FC