[Premium-Rx] DXing in MW nearfield

[Carcia, Frank A. HS]

That is why most receiver specs measure
dynamic range with 2 signals spaced 100 KHz. to take advantage of the filter
in the first IF.     fc

-----Original Message-----
From: michael j brown [mailto:piggin at mindspring.com]
Sent: Thursday, May 29, 2003 11:32 PM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] DXing in MW nearfield


My situation is similar to johns.One mile from a 5kw on 570, and three
others in that class within a couple of miles.In the specs for the 3031A
they specify the strength of the wanted signal@ 31.6microvolts and then use
two signals at +30 and +60 kc at a strength of 100millivolts(in the 100 to
525kc band) This should still keep products below the wanted signals level.
Mackay also says A 1 millivolt signal will change less than 3db with a
100millivolt signal 10kc away.These are the only specs I have ever seen
written in this manner.Note it does not address volts of RF.Blocking
performance is ok in my real world signal hell.But the preselector really
helps.Most radios without massive LO injection and giant dynamic range, in
combination with some preselection can't hack it.The 3031A does not feature
massive dynamic range.Or watts of LO injection.But the preselector works.I
imagine many premium RXs would fare poorly within the distance John is
coping with.But I doubt many write specs that would really tell you what
happens with 2 volts of rf 10kc away will cause your radio to do.....

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