[Elecraft] K2 - Best Practices - Optimization

[Don Wilhelm]

Drew,

When adjusting L34, the peak is quite broad and is difficult to 
determine exactly where to set it - if you can discern no difference, 
then set it somewhere between 1 and 2 turns in from the top and be done 
with it.   Even if you want to refine the setting, start with this 
'adjustment'.

When observing with Spectrogram, I find the best signal source is the 
7000 kHz birdie.  Set the bandwidth to 400 or 500 Hz, turn the preamp on 
and observe both the peak of the signal and the noise floor of the 
receiver (outside the receiver passband).  While the signal is still at 
its peak, you will find a point where the noise floor drops by a small 
amount.  If that ' best signal to noise ratio' is not found near the '1 
to turns in' setting you initially had, it is the wrong point.

As for the AGC Threshold setting, a small amount of difference between 
AGC on and AGC off is OK, but if the difference is large, decrease the 
AGC Threshold voltage from the 'standard' value of 3.8 volts.  Expect 
the S-meter response to change with each different setting of the 
Threshold level, and you will see more interaction between CAL S LO and 
CAL S HI.  If an S-9 response with a 50 uV input is important to you, 
then some 'playing' with the 3 settings (AGC Threshold, CAL S LO and CAL 
S HI) will be necessary.  If the AGC Threshold is set too low (usually 
below 3.65 volts), the S-meter readings may become quite 'squirrelly'.  
So you have 4 parameters that you must compromise with (the 3 above plus 
the S-9 response) - you may not be able to get them all to fall in line 
at your chosen AGC Threshold, and you will have to sacrifice one of 
them.  If you use between 3.75 and 3.8 volts as the AGC Threshold, you 
can usually get the others to fall in line - so take your pick.  That is 
the whole story as I know it.  Dave White recently posted a mod to 
increase the number of adjustment pots from one to 3 which can give more 
independent control over the AGC and S-meter settings.

73,
Don W3FPR

drewko1 at verizon.net wrote:
> I'd like to know of a good procedure for the IF Alignment (L34). I
> tried it with Spectrogram but I really don't see any definite "best"
> alignment point; same for doing it by ear.
>
> As for the AGC Threshold adjustment... I read somewhere (sorry, i
> forget who) that you should adjust it just to the point where turning
> on the AGC does not result in a reduction of low-level rcvr noise (no
> antenna). I tried this and it makes for a really hot receiver.
>
> 73,
> Drew
> AF2Z
>
>
>
> On Sun, 30 Sep 2007 12:30:40 -0400, David Wilburn wrote:
>
>   
>> I have been using my K2 for a bit now.  I have done a couple of 
>> alignments on it, as I learned lessons what I did not get quite right 
>> previously.  I listen quite a bit more than I transmit.  I do ok around 
>> 15wpm, but I'm not quite happy with where I am, so I listen and work on 
>> improving my copy.
>>
>> I have followed Tom and Don's alignments with Spectrogram, as I do not 
>> have much in the way of test equipment.  I am at the point where I would 
>> like to go back through and try it again, and play with the settings a 
>> bit more, to get them to fit what I like, where I stayed near the 
>> defaults previously.  I do have the XG2, the wide band noise generator.
>>
>> Additionally, I have played with the K2 quite a bit to understand how to 
>> best use it to pull in marginal signals.  This is where best practices 
>> would come in handy.  How do the folks that are more experienced, pull 
>> them in?
>>
>> Has anyone done any write ups on optimizing the K2?  Anything on 
>> settings for best pulling in the signals?
>>
>> Elecraft, thanks for the radio and the great forum.
>>     
>
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