I wonder if this is phase noise caused by a very strong signal rather close to 1.8 MHz. 

----- Original Message -----
From: Bob Sikkila <[log in to unmask]>
To:  [log in to unmask]
Date: Monday, Nov 8, 2010 8:06:24
Subject: 160 meter noise

>
>
> hi All, I recently put up an alpha delta dxlb antenna for 160, 80 and 40 =
> meters. It's only 100 feet long and very narrow especially on 160. I =
> have made several cw contacts and I am satisfied with the antenna, but I =
> have had an annoying swishing or rushing noise that crawls down the band =
> and covers my operating frequency right at about the time the other =
> station is passing along his name and qth. It happens every time I =
> transmit. After the noise passes, the band is clear again. I have tried =
> listening with another antenna and using a different rig with the same =
> result. I hear that noise constantly from about 1.830 to 1.840, but it =
> doesn't seem to move until I transmit. I operate in the bottom 25 khz of =
> 160. Has anyone had this problem and do you know what it is and how to =
> get rid of the noise? Thanks.=20
> 
> Bob K8MXC