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Re: Attenuator and RF Gain Settings

Posted by Joe Subich, W4TV-4 on Feb 03, 2010; 5:09am
URL: http://elecraft.85.s1.nabble.com/Attenuator-and-RF-Gain-Settings-tp4503505p4505604.html



> I wish I could set it higher than 008. I am also in a
> relatively quiet location but on 20m with an AGC threshold of
> 008 my atmospheric noise is normally above the AGC threshold.

If one looks at Jack Smith's graphs, the K2 threshold (between
-80 and -90 dBm) would be about 11 or 12 for the K3 and the
slope is about 5 or 6.  Jack's measurements show that even at
8, the K3's AGC threshold (onset of AGC) is down around -100dBm.  

Sherwood shows the K3's AGC threshold at 2.1 uV vs. 10 uV (no
preamp) for the K2 and .6uV vs. 1.7 uV with the preamp.  I
find it interesting that Sherwood's measurements of the
FT-1000D (6 uV) and FT-1000MP MK V (3 uV) also show higher
AGC thresholds with the preamplifier on.    

73,

   ... Joe, W4TV
 



> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of ab2tc
> Sent: Tuesday, February 02, 2010 5:08 PM
> To: [hidden email]
> Subject: Re: [Elecraft] Attenuator and RF Gain Settings
>
>
>
> Hi,
>
> I wish I could set it higher than 008. I am also in a
> relatively quiet location but on 20m with an AGC threshold of
> 008 my atmospheric noise is normally above the AGC threshold.
> So when I want comfortable listening I back off the RF gain
> until the S-meter shows about S4 or so. Not a big problem,
> but I would prefer that the AGC threshold could go higher.
> Having it stored per-band, too, would be really, really nice
> and it makes sense.
>
> Knut - AQB2TC
>
>
> Don Wilhelm-4 wrote:
> >
> > I just thought of something that might help those confused
> by the AGC
> > Threshold setting.
> > One other way to look at the required AGC Threshold level
> is to think of
> > it as an S-meter level
> > If your noise is S-1 or lower (on the K3's S-meter), you
> can set the
> > Threshold to 002 or higher and all may be well
> > OTOH, if you have an S-7 noise level indicated, the AGC
> Threshold should
> > be set to 008 or higher.
> > <snip>
> >
>
> --
> View this message in context:
> http://n2.nabble.com/Attenuator-and-RF-Gain-Settings-tp4503505
p4504035.html
Sent from the Elecraft mailing list archive at Nabble.com.
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