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Re: [TowerTalk] Remote Preamp or In the Shack

To: <>
Subject: Re: [TowerTalk] Remote Preamp or In the Shack
From: "Dan Schaaf" <>
Date: Thu, 19 Jan 2012 21:39:05 -0500
List-post: <">>
In addition to my IF DSP, I also have the Timewave DSP-599zx and it has AGC
in addition to the noise reduction. It also has a CW Spotlight which makes
the weak CW pop right out of the headphones.
On top of all this, I have the APF turned on. The APF is a triangular filter
in the FT-2000 which really digs cw out of the noise.
So, when you add all of these together, a really weak CW on 160 meters can
sound like armchair copy in many cases.
This Timewave unit might be just what you are looking for.

Best Regards
Dan Schaaf
Cape Cod Instruments
Tel: 941-766-0706
Fax: 941-766-0707

"Problems cannot be solved by the same level of thinking that created 
them." - Albert Einstein

----- Original Message ----- 
From: "Rick Karlquist" <>
To: "Dan Schaaf" <>
Cc: "Pete Smith N4ZR" <>; "TowerTalk" 
Sent: Thursday, January 19, 2012 9:26 PM
Subject: Re: [TowerTalk] Remote Preamp or In the Shack

> Dan Schaaf wrote:
>> My take on this has always been, if the atmospheric noise can be heard in
>> the radio, above the inherent radio noise ( with no antenna connected )
>> then you don't need a preamp. The preamp will amplify the noise as well 
>> as
>> the signal.
> The problem with this concept is that you end up with no AGC,
> because of inadequate IF gain in nearly all receivers, especially
> when using 200 Hz CW bandwidth.  The correct fix is to add about
> 20 dB more IF gain.  I actually did this to my FT-757.  It worked
> great, I got AGC on the weakest signals.  You can also add
> enough preamp gain to get the AGC at the threshold on atmospheric noise.
> The problem with this is that your preamp is subject to overload.
> A third idea I have been thinking about is to build a audio AGC,
> which has the advantage that no receiver modification is necessary.
> It would likely be necessary to have an audio roofing filter to
> get rid of out of band audio hiss and hum.  It might be possible
> to find some off the shelf audio processing box with AGC to do this.
> Equipment for DJ's, radio stations and/or recording studios would
> be likely to have an AGC function.
> Rick N6RK
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