[R-390] sensitivity

[wb5uom at hughes.net]

Russ,
May I inquire if your statement is in reference to HF only or across the 
board on frequency? (VHF / UHF)

I mentioned a long time ago  (and took slome flack) that my R-390A as well 
as the Drake R8-B and the newer  WinRadio G313i all go to the bottom of my 
Aeroflex 3920 in lsb/usb mode  which is -138Dbm.
True its MDS ... but I am lucky to be out in the Country with an almost 
nonexistent noise.

With 350ft of wire in the air, if I turn off all other noise making devices 
(TV, A/C etc)
since I have spent 31 years listening to a 1Khz test tone making me half 
deaf, with headphones, I can copy signal down in that region.

I use the Volmet station in Hawaii (6mhz and or 8mhz or 13 Mhz)and just wait 
to see at what point can I hear and understand what is being said (since 
they broadcast at a predictable time all the time)

I know - most on here do not like the MDS method of test

Just random comments -

David/ WB5UOM


----- Original Message ----- 
From: "Roy Morgan" <k1lky68 at gmail.com>
To: <wb3fau55 at neo.rr.com>
Cc: "R-390 mailman" <R-390 at mailman.qth.net>
Sent: Friday, October 07, 2016 12:46 PM
Subject: Re: [R-390] sensitivity


>> ... sensitivity on all bands  as .07uV.  So the tightest filter in this
> is 300hz.  So now we are  talking incredible receiver  right?  I  have my
> suspicions on that.
>
> Russ,
>
> Claims of receiver sensitivity very much below one microvolt should be
> regarded with suspicion.  Some of the factors in making such measurements
> are:
>
> - actual input impedance of the receiver with respect to the test signal
> source impedance
> - method of predicting the receiver input signal level
> - possibility (likelihood!) of leakage in the test signal generation
> system at such low levels
> - bandwidth of  the receiving system
> - overall measurement system quality and capability
> - eagerness of the operator to proclaim astounding performance for his
> receiver.
>
> I know a fellow who owns a Ferrari Testarosa automobile.  I think it can 
> go
> nearly 200 miles per hours.  He seldom gets a chance to do that.
>
> Bob Camps just-posted comment relates directly:
> "If you are dealing with an HF radio below 10 MHz, none of this is all 
> that
> big a deal. Any time or place
> you would ever *use* the radio, the noise into any rational antenna is 
> well
> above the KTB
> noise floor."
>
> Now, I'm going to go refresh my memory about the meaning of "KTB nose
> floor".
>
> -- 
> Regards,
> Roy
>
> Roy Morgan
> k1lky since 1958
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