Same issue/problem on new K3.....
Charles Harpole
k4vud@hotmail.com
> From: hjohnc@gmail.com> To: tentec@contesting.com> Date: Sun, 11 May 2008
> 19:14:57 -0400> Subject: Re: [TenTec] AGC Threshold, RF Gain, Volume> >
> Thanks Merle!> > That was a good explanation of what I was experiencing. I
> like version 2 > firmware, but will try v1.373b5. I've tried it before, but
> never for long > enough to get used to it.> > 73 de K1ESE> John> > > -----
> Original Message ----- > From: "Merle Bone" <merlebone@charter.net>> To:
> <tentec@contesting.com>> Sent: Sunday, May 11, 2008 3:15 PM> Subject:
> [TenTec] AGC Threshold, RF Gain, Volume> > > > John,> > Yes the RF gain
> control changes the AGC threshold level - just like > > setting> > it in the
> AGC menu. One of the original Orion firmware developers, Doug> > Smith, wrote
> in a paper describing the Orion Digital AGC System:> >
> -----------------------------------------------------------------------> >> >
> "In digital AGC systems, it is relatively easy to provide a variable> >
> threshold or "knee." Input signals below the threshold do not actuate the> >
> digital AGC and are not compressed. At thresholds well above the receiver> >
> noise floor, a receiver therefore gets quiet when only puny input signals> >
> are present in the passband. At thresholds near the noise floor, all > >
> signals> > are boosted to meet the output-level criterion. The net effect of
> a > > variable> > threshold is very much like that of an IF gain control."> >
> ------------------------------------------------------------------------> >>
> > Consequently, if you "ride the RF gain" and set it for a good audio level >
> > on> > a stronger signal, weaker signals will not activate the AGC and they
> will > > be> > too low in volume. I've never been fond of this process. I
> think it was a> > "crutch" to offset the gain distribution issues in the new
> Orion V2> > firmware. There was an AVC loop in the V1 code that prevented the
> audio> > stages from being overdriven and distorting. That code was taken out
> of > > the> > V2 firmware and there have been peak signal distortion issues
> since. That> > started some people doing what you described with the audio
> and RF gain> > controls. Unfortunately you are seeing some of the unintended
> consequences> > of operating the radio like that. Hopefully Ten-Tec will
> address the> > distributed gain level issues in the next Orion V2 firmware
> release - > > maybe> > they will put the ALC code back.> > 73, Merle - W0EWM>
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