Message-ID: <9CA1BD0BAA5346E3B622FC21CB38ECCB@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <4FDDE3C9.8080505@iup.uni-heidelberg.de>
In-Reply-To: <4FDDE3C9.8080505@iup.uni-heidelberg.de>
Date: Sun, 17 Jun 2012 17:48:19 +0100
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Subject: Re: LF: Further MF impressions
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'''What do others know about the ground wave range in summer and in the
> afternoon? When does the band open? Similar to LF?''

Stefan,  Ground range is really  a  product of  erp + data processing (if 
your are digital)  , 75 miles  is about the  saturation range  , you  may 
remember the  'Beacon Bedlam'  when  500  was  first allocated  and  lots of 
qrss  beacons where  established (Luckily  Myself and  Gray are over 100 
miles  north of know  end of  civilisation   Watford-gap and  missed out on 
this !)

Next is the  skip  round  175/ 250  miles , there seemed  to  be a  belt 
round  that  distance  that  was  always difficult to  work, then  next 300 
miles  +  in the  night

There  where  a  good  set of  propagation/ time  delay / phase plots  on 
the  old uk500khz  web site  using the  ZL psk-software , showing  the 
phase  distortion at times of  qsb on  500  , that  gave a indication  as to 
why  psk-31  was  all ways  a very poor mode over  distance ,


This  plot  from  DK8KW , with  one  long  run of the  Op beacon  , gives  a 
good  over view of the  changes of  conditions  over the  night  , I only 
started to  decode off  air quite late on , But  I  could  copy your  CW 
much earlier in the  night, so I assume  the  station  is  working correctly 
, but  later  decodes  are  many  dB  down  on the  South  Uk levels , but 
skip  may of  been  the  simple  reason , I was  using a 40ft  x 2 inch end 
fed vertical  mast , 6 ft off  the  ground,  at the  time  , with  only the 
pre-selector in the  Rx as the  tuner

73 -G..

http://uk.groups.yahoo.com/group/rsgb_lf_group/photos/album/96277963/pic/1714843914/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc

--------------------------------------------------
From: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.de>
Sent: Sunday, June 17, 2012 3:03 PM
To: <rsgb_lf_group@blacksheep.org>
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
>