[R-390] Antenna Noise

[Bob Camp]

Hi

Here's a link www.ofcom.org.uk/static/archive/ 
ra/topics/interference/documents/rsgb.pdf to a little four page thing 
on noise. One of the things it shows is that the picture changes fairly 
dramatically at about 15 MHz. Below 10 MHz the 8 db  number is probably 
optimistic most all of the time. The chart they give shows numbers in 
the 15 to 20 db range for most of the 500 KHz to 10 MHz region. The 
other thing they plot is man made noise. In that case you are talking 
about 50 db of noise by the time you get to 1 MHz. A lot is going to 
depend on how much noise you get from your neighbors.

	Take Care!

		Bob Camp
		KB8TQ


On Aug 20, 2004, at 12:46 PM, Kenneth G. Gordon wrote:

> Concerning noise levels below 30 Mhz: while I agree that noise
> in this range averages 8db, as implied by the word "average",
> there are times when it is both significantly lower, and
> significantly higher than 8db.
>
> Although, hanging a pre-amp on an R-390(A) is completely
> unnecessary, IMHO, there ARE times when, with OTHER
> receivers, a lower receiver noise level would be very useful.
>
> In my experience, some of these times were when I was doing
> 'phone patching into SEA during the Vietnam troubles. I was
> operating for AFMARS and working above the 20 meter band.
>
> I purposely modified the driver I was using, an SB-101.5 (!), for
> lowest receiver noise possible, and could often run phone
> patches long after the SEA stations could not be heard at all on
> a KWM-2A sitting along side the SB-101.5, because of the
> higher noise level in the KWM-2A.
>
> Admittedly, this did not often occur, but it did often enough
> that I thought the effort well worth while. Hopefully, the guys
> in SEA thought so too.
>
> Ken W7EKB
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