[Elecraft] K3 AGC and Apparent Noise and Signal Distortion

[N2TK, Tony]

Don,
I agree with that. When I am in a SSB contest from KP2M I have the RF gain
at 3 o'clock all the time. For 20-160M I have on the Attenuator. For 15M no
Attenuator. For 10M I have the Preamp on (maybe that will change once 10M is
alive again). Don't much vary the AF control - usually at 9:30 for my Heil
headset. If someone starts crowding me I may have to use the HI CUT control.
AGC SLP - 2 and AGC THR - 8.

73,
N2TK, Tony

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Thursday, February 04, 2010 10:14 AM
To: Wes Stewart
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 AGC and Apparent Noise and Signal Distortion

Wes,

I agree that constant "riding the RF Gain" should not be necessary,  But 
on any one band, reducing the RF Gain to the point where the atmospheric 
noise is not readily apparent does make a lot of sense to me.  Set in 
that way, one does not have to listen to a lot of band noise and the AGC 
still works (albeit at a reduced level), and there is still S-meter 
response for those who want to give reports based on the meter reading.
Once set for any one band, it does not need to be changed - AGC and the 
AF Gain will take care of the rest - I would not refer to that as 
"riding the RF Gain control".

Now --, if one wants to turn off the AGC altogether, yes, the only 
technique that makes sense is to use the RF Gain as the 'volume' control 
(in addition to preamp and attenuator controls) - the technique as I 
learned it is to disconnect the antenna and turn up the AF Gain to the 
point where the internal receiver noise is apparent, but not bothersome 
(leave it set there), and use the RF Gain to set the desired output 
audio level - in this case, changing the RF Gain is the only way to 
control the volume of what is coming out of the headphones (or 
speaker).  I cannot imagine anyone operating that way on a normal basis 
with a modern receiver with good AGC, but I know some do that based on 
habits formed long ago with old receivers using diode detectors - we had 
to do it that way because the BFO would overload the AGC and kill the 
receiver gain.

73,
Don W3FPR

Wes Stewart wrote:
> IMHO, riding the r-f gain control (really i-f gain in the K3) in a
properly designed receiver should be totally unnecessary.
>
>   
>
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