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

To: topband@contesting.com
Subject: Re: Topband: Sherwood data...Recovery time???
From: "Barry N1EU" <barry.n1eu@gmail.com>
Date: Fri, 16 Feb 2007 21:33:27 +0000
List-post: <mailto:topband@contesting.com>
On 2/16/07, HFDXJUNKIE@aol.com <HFDXJUNKIE@aol.com> wrote:
> I use a Mark V with no filters at all into an inverted V
> with the apex at 55 ft, scary huh? Well anyway, not being an electrical
> engineer, 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.  I tried two late
production MP's and both rigs were plagued with receiver recovery time
in cw mode (fast agc) on the order of hundreds of msec in weak signal
conditions.  Recovery was equally slow from both transmit turnaround
or from strong signal bursts.  Partial work-around is to minimize AGC
action using less RF gain, more AF gain if possible.  It was very
frustrating and I sold both rigs.

It was so bad I originally thought it was a problem with the antenna
relay, since I routinely missed the first few cw elements of weak
stations answering my cq in contests.  But then I made a series of
measurements and comparisons and conclusively characterized the AGC
problem.

73,
Barry N1EU
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