[Elecraft] RF gain sweet spot

[Don Wilhelm]

Dave,

By setting the RF Gain as you did, you have maximized the dynamic range 
of your receiver.
The lowest level signals that you will be able to hear (and understand) 
will be at your local noise level - there is no sense (to me at least) 
to use more than the amount of gain that will give you a small bit of 
atmospheric noise in the audio.

By reducing the RF Gain, you have set that point where signals stronger 
than your local noise will be heard - they just seem to "jump out of the 
noise".

Add to that the fact that your ear gets accustomed to hearing a constant 
noise level, and will ignore signals that have less intensity than that 
level - so reducing the noise into the ears is good.

The K3 has ample gain, and without human intervention, the band noise is 
just like another signal - if it is present, the K3 will amplify it.

Note that this is a different concept than "riding the RF Gain" - it is 
a simple, listen for the band noise, and reduce the RF Gain until it is 
at a tolerable level - then do not change the RF Gain for that 
band/antenna combination.  Use the AF gain to further vary the audio 
level - the AGC will take care of the rest.

73,
Don W3FPR

On 7/20/2011 6:55 PM, K7WIA wrote:
> I found something interesting when I was working the CQ VHF contest this last
> weekend.
> I live in the city in which my noise level stays around S3.
> while searching for weak signals, I started to reduce the rf gain. as I
> reduced the gain I watched the S meter go down  and as I contuned to reduce
> it more the S meter would start to climb back up.
> I found if I set the RF gain to where I got the lowest S meter reading ( S1
> ) and then Increase the gain ever so slightly just to the point to where I
> would get the 2nd bar on the S meter to flicker was the sweet spot. as the
> RF gain is reduced my noise floor dropped, but it had no effect on the
> signals, so it seems to improve the Sig to noise ratio.
> so I now I reduce the gain to the lowest S meter bar ( S1 ) and then add
> gain just untill the 2nd bar just wants to flicker.........so I guess this
> is called Dip the S meter
> I don't know how well this works on hf as I work mostly 6 meters.
> I thought I would pass this tip along. it might now work for everyone but it
> sure helped me dig out the weak ones..... maybe someone in the know can
> explain what is going on.......
>
>