[Elecraft] "Hot" K3 [comments and suggestions]

[Don Rasmussen]

Interesting...

I can make K3 #2308 more like K3 #272 if I set the S-MTR Offset and range
to their limits AND, turn the AF GAIN to LO on K3 #2308.

If that's all there is to it, I'm fine. 

But it is shocking to see that much variance between seemingly identical units at first. 

I'd like to see more range in the S-Meter CONFIG controls to account for this. And maybe an AF LO MED and HI? 

In any case I'd expect #2308 and later to leave the factory (even though it's a kit), with the default settings of the CONFIG being somewhere S9 = 50 uv

I also strongly desire that the RF gain control would not affect the S-meter. 

All that having been said, if Wayne does not think the gain margin is a problem, I am relieved, happy, and suprised at not having to send the new radio in for repair. 


[Elecraft] "Hot" K3 [comments and suggestions]
wayne burdick n6kr at elecraft.com 
Mon Mar 16 18:10:58 EDT 2009 

Just to provide a counter-example....

I almost never back the RF GAIN control down on my K3. It has huge 
dynamic range. Unless I'm besieged by multiple S9+30 or greater signals 
within the crystal filter passband, I don't find it necessary. (Note: 
We're getting close to a new firmware release that provides additional 
DSP AGC tools that will make riding the RF GAIN even less necessary.)

The K3 is not substantially different in overall RX gain from other 
modern radios, although it may, as some observed, have a more accurate 
S-meter at the low end. During the design process we measured the 
antenna-to-AF OUT gain of several radios to make sure we were in the 
right ballpark.

I do turn the preamp OFF most of the time below 15 m.

I sometimes use the attenuator with monstrous AM broadcast signals (in 
the 0.5-1.6 MHz band), but rarely other than that.

I'm using all of the AGC defaults, and have CONFIG:AF GAIN set to HI.

NR is handy in many cases if you have high atmospheric noise. Try a low 
setting first.

If you think there's too much gain, you can set AF GAIN to LOW (making 
it more like a K2), turn off the preamp, and adjust the AGC controls.

Also, I suggest using only very low values of CONFIG:FLx GN, as well as 
small (+) values of MAIN:RX EQ, if you use these at all.

73,
Wayne
N6KR