On Wed, 2 Feb 2005 23:46:12 -0500, "Brian Denley"
wrote:


My WR-G313i does indeed have the advertized -138dBm noise floor, and
even the S-meter reliably measures down to that level - with 1dB
accuracy.

Not speaking of the ultra-sharp continuously variable IF filters down
to 1Hz bandwith.

Now *that's* what I'd call winning the contest hands down. ;-)

Geoff

Geoff:


-143 dB was the noise floor of the R-390A, according to web info.
Otherwise, of course, it was an old tube (32 of them!) boatanchor with
mechanical tuning, weighed a ton, and had none of the amenities that modern
digital radios provide. But it WAS quiet!

--
Brian Denley
http://home.comcast.net/~b.denley/index.html


Thanks for the info Brian, sounds indeed awesome, I think I'd love to
own this radio (and I thought I had no space left! :-).

But frankly, I am still a bit confused about the noise floor. Yes I
did see the Web pages which mention -143 dBm and one even says
-147dBm, but some other pages specify less, for example -127 dBm,
which seems to me more realistic, considering the sensitivity specs,
which appear to be poorer than my WR-G313i (I have verified its
sensitivity with a good signal generator, and it is actually about 2-3
dB better than specified):

R-390A specs:
http://members.aol.com/tcsopr/r390a.htm
WR-G313i specs:
http://www.winradio.com/home/g313i-s.htm

How could a receiver with a higher noise floor have a better
sensitivity?

See also the original military specs on:
http://209.35.120.129/mil-r-13947b.pdf

and this table
http://www.sherweng.com/table.html
which shows the noise floor as -137dBm,
i.e. about the same as the WR-G313i.

Confusing, eh?

I also note the dynamic range of the R-390A is rather poor:
according to the specs on
http://members.aol.com/tcsopr/r390a.htm
it is only 52.7 dB (but this can't possibly be correct?),
and on http://www.sherweng.com/table.html
it is more reasonable 79dB (or 81dB wide-spaced), but it is still
nothing compared to the 95 dB of my WR-G313i...

Geoff