[Elecraft] K2 PLL trouble

[Bill Coleman]

On May 9, 2005, at 12:34 AM, Ken Lotts wrote:

> The BFO test is also a wee bit out of range.
>
> The upper freq is 4917.81 (OK)
> The lower freq is 4915.04 (HI)

I don't know about all the PLL problems, but I do know how to deal  
with this problem.

Check that C174 and C173 are the right values - should be 82 and 220  
pf, respectively, for a Rev B K2. Some earlier models used larger  
caps. I think it depends on the type of L33 inductor used. The  
current design uses a pre-wound toroid.

If the frequency range is too high, parallel C174 and C173 by 47 and  
100 pf, respectively. You can safely add up to 56 pf and 120 pf,  
respectively.

If this doesn't help, then add a couple of pf between the joined X3  
and X4 landing to ground. I used 3 pf and this moved my lower  
frequency down about 800 Hz without really affecting the upper  
frequency.

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