[Elecraft] K2 IF Amplifier alignment

[Ron D'Eau Claire]

The peak is subtle, at best and it's not an important adjustment, once you
are in the general ball park. 

It does slightly affect the S/N ratio, but unless you have a really terrible
antenna, atmospheric noise limits the ultimate weak signal ability of the K2
across the HF bands anyway (try disconnecting your external antenna while
listening to band noise on a quiet frequency. if you hear the noise drop,
the band noise and not the K2's internal noise are limiting what you can
hear. Use the narrowest filter setting you normally use.)

One way offered by Gary at Elecraft years ago that I know works is to hook a
DMM to read ac volts across the speaker or phones jack, and with the AGC off
and gains up enough to produce a reading, adjust for a peak. Again it'll be
very subtle. 

Another way that is a little better at optimizing the S/N ratio is to look
at a weak signal on Spectrogram. An Elecraft XG generator is good for this.
You want a very stable and weak signal that is a bit above the background
noise (with no antenna on the rig) and, preferably, a 50 ohm dummy load on
the antenna jack. Most generators provide the load along with the signal. 

Watching the signal and the noise below it on Spectrogram, tune for the
highest peak above the noise. This will not necessarily be where the total
value is highest. Look for where the spike representing the signal stands
tallest above the noise, even if the absolute value isn't quite as high as
another setting. 

Again, it's broad. Did I mention that the peak is subtle ;-)

Ron AC7AC

-----Original Message-----
> -----Original Message-----
 
> Meanwhile back with K2 #5942)....
> I am realigning my K2 (had to tighten up the amp devices anyway) I was 
> never very happy with the IF Amp alignment (P64) when I first built 
> it. There does not seem to be a clear peak on L34 adjustment - just a 
> general area where it seems to be highest. I am using another rig on 
> LP into a dummy load as a signal source - I can hear the internal 7000 
> MHz signal but it doesn't seem to peak particularly..
> My one comment about the K2 is that it seems a little short 
> on gain (but OK with the DSP). 
> Do I have a problem with the IF amp alignment or my 
> experience the same as others please? Grateful for any advice 
> and comments (makes a change from K3 chat)
> 73 Nick G3RWF