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 th
ere 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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