[Elecraft] SSB xtal replacements

[Ron D'Eau Claire]

Be sure the AGC is OFF when using spectrogram to adjust L34 that way.
Otherwise the AGC will "fight" you ,trying to keep the audio output
level constant as you adjust L34. 

Personally, I prefer the simpler way suggested by Gary Surrency a year
or so ago:

1 - On the Control Board, connect your DMM to the end of R2 the farthest
from the top edge of the board. R2 is one of three resistors in a row
near the top edge of the Control Board on the right side looking down
into your open K2. You must connect the DMM to the lowest end (farthest
from the board). 

2 - Turn on the K2 and let it warm up a few minutes.

3 - Tune in the 7.MHz "birdie" with preamp ON.

4 - Adjust L34 for MINIMUM reading on your DMM. 

What you are doing is measuring the AGC system's response to the birdie
and adjusting L34 for the greatest response, meaning that L34 is
"peaked". On my K2, the reading I see is about 3.649 volts at the
"bottom" of the dip in the voltage. Turning L34 1/2 turn off of the
"peak" produces voltages at R2 of 3.657 in one direction and 3.693 in
the other direction, so the "dip" is very easy to spot on a DMM capable
of showing four digits. For me, that's easier than trying to see the
peak of the spike on the PC monitor. 

Ron AC7AC
K2 # 1289


DHK2BOB wrote:

>1.  Using Spectrogram6 I still can't tell when L34 is aligned! I just 
>left
it 
>one and one half turns from the top!  This is not a problem but just an
>observation which I'm sure relates to my inability to detect the subtle

>differences. I had AGC off and fiddled with the RF gain control. I
thought 
>that the only difference I noticed was not in the "height" of the spike
but
a 
>slight change in the distance between the top of the spike and the 
>"noise"
>down below. That is, tuning L34 seemed to change the noise but not the
spike. 

I installed Spectrogram on my notebook and on my desktop (with CRT
monitor). On the CRT monitor it is indeed almost impossible to see
differences when fiddling with L34. On my notbook however this is quite
easy: the notebook is equipped with a TFT monitor and I can see the peak
becoming just one pixel higher or lower when fiddling tuning L34. So
with Spectrogram I could find the peak while monitoring the noise level.
Works great.

Piet, PE1OQX



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