[Elecraft] K2 BFO Test

[Bill Coleman]

On Dec 9, 2005, at 8:56 AM, Don Brown wrote:

> I have used this method on 3 or 4 of the K2's I have built. I use a  
> 1pF or
> 2pF NPO cap to lower the bottom end of the range to get it to meet  
> the spec.
> I agree with you on pulling the crystal much with this method. I  
> would not
> recommend cap values above maybe 3 or 4 pF. I have never needed  
> more than 1
> pf. Padding C173 and C174 is a better method if the radio needs  
> more than 1
> or 2 pf. I believe this method was suggested by Gary at Elecraft  
> some time
> back. At any rate it is a little easier to do than the padding or  
> change out
> of C174 and C173

To get the BFO range I needed for RTTY, not only did I have to pad  
C173 and 4, but after I had added maximum capacitance there, I went  
ahead and added 2 pF to pull the crystal. I have not noticed any  
stability problems, and the BFO range is just about perfect.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901