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Re: [RFI] Damned Amtrak

To: rfi@contesting.com
Subject: Re: [RFI] Damned Amtrak
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Sat, 29 Dec 2012 16:46:08 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On 12/29/2012 1:25 PM, dalej wrote:
You might consider a Timewave ANC-4 noise canx device.

Perhaps -- the MAJOR problem with these boxes is that the RF detection circuit that does T-R switching is a NASTY key click generator that will make your neighbor hams very unhappy. An easy cure for this is to put the noise canceller in the RX antenna input, if you have one.

The MFJ equivalent is supposed to be better at noise cancelling, but I haven't seen one and don't know about clicks. And, of course, be aware of their QC problems and prepared to fix cold solder joints.

As Dale has mentioned, the key to these working well is having a noise sense antenna that is as close as possible to the noise. You want the ratio of "noise" to desired signal on that "sense" antenna to be as high as possible so that you cancel more noise and less desired signal. :)

73, Jim K9YC
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