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Re: Topband: Sherwood data...Recovery time???

To: "Barry N1EU" <barry.n1eu@gmail.com>, <topband@contesting.com>
Subject: Re: Topband: Sherwood data...Recovery time???
From: <wb6tza@socal.rr.com>
Reply-to: wb6tza@socal.rr.com
Date: Fri, 16 Feb 2007 16:31:57 -0800
List-post: <mailto:topband@contesting.com>
cleanest and simplest answer is to run with the AGC off.  I almost always 
use an external receive antenna with lower overall level signals, and when I 
add in the TX antenna as a choice on the receive antenna selector, I usually 
pad it down to be similar in overall level to the average receive antenna at 
the station.  Then selecting antennas with the AGC off doesn't blow my ears 
off.

Even when using the TX antenna to receive, I find it is nearly always better 
to run with the AGC off.  One of the shortcomings of modern receiver design 
is the inability to deal well with that mode.  Allowing the strong noise 
spikes, key clicks, etc, to clip in the audio stage causes the hole made by 
the spike to be only as long as the spike itself, instead of spike plus AGC 
decay timing.  Personally, I find Fast AGC to be very unpleasant to listen 
to.  Fast AGC tries hard to make the audio level of the desired signal and 
the noise level the same,  a no good way to hear a CW signal.  When you add 
in the pumping effect caused by strong signal from the jerk who keeps 
calling the DX right through the DX transmission to YOU, its intolerable.

Use the pad selection, IPO, etc controls available to reduce the overall 
signal level so that the audio level with the AGC OFF is reasonable.  Keep 
the audio gain control as low as you can, and then raise the RF gain until 
the audio level is enough, but not clipped on normal signals.


See how that does for you

Robin WA6CDR


I notice the recovery time I guess you would call it in simplex pile  ups
>> after I call, and begin to receive..it seems like the receiver is deaf 
>> for a
>> fraction of a second and do not hear the station coming back to me, than 
>> the
>> second request I hear perfectly.
>
> This is a glaring deficiency in the AGC design.  >  But then I made a 
> series of
> measurements and comparisons and conclusively characterized the AGC
> problem.
>
> 

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