[R-390] r390a noise floor

[jgedde at optonline.net]

When mine is restored, (soon) I'll check it.  I have equipment capable of
measuring that low...  But, the following caution is made: -143 dB compared
to what?  dB is always a ratio...  Without knowing what Chuck used, we can't
speculate...  All that said, I wouldn't lose any sleep over the noise floor.
Suffice it to say, the r390a's noise floor - especially if you optimize the
tube locations - is more than sufficient for our modern day, noise filled
environment.  Disconnect your antenna, put the receiver in MGC mode,  then
short the antenna balanced inputs together.  Compare that to what you hear
to what you hear with the antenna connected on a dead frequency.  If it's
dramatically different - which I'm sure it will be - you needn't worry about
the R390a's noise floor.  -143 dB is crazy low (even compared to a
thunderclap) and will almost certainly never be achievable in real life
except in a screened lab.

-----Original Message-----
From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On
Behalf Of jm
Sent: Monday, April 22, 2019 5:15 PM
To: R-390 Forum <R-390 at mailman.qth.net>
Subject: [R-390] r390a noise floor

Hi guys,

Anyone has had some experiences about a noise floor better than -100 dbm?


  " the R390A is capable of copying signals down to its -143db noise floor,
close to the galactic limit " (C. Rippel).

Is there something I am missing?

Jose EA8DCP

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