[Elecraft] Problem: K2 Audio Tuning Click or Warble

[Bill Acito W1PA]

>
> RFC15 supplies the 5V to the VDD pin of the MC14570...   how can there be
> 4.23V at the pin if RFC15 is open and there is no other VDD pin on the IC?
>


I'll answer my own question: apparently, very easily.

Power-off DC resistance check confirmed that the RFC15 was open. No visual 
indication of
any problem with it when examined.  I had a larger, green version of the 
100uH left
over from another mod, so I replaced it and low-and-behold, no warble. 
Someone
mentioned to me that later versions of the K2 have the sturdier part -- I 
hope so.

The MC14570 must have been getting DC from the inputs in lieu of no DC at 
VDD, hence
the near-5V reading.

A ham and builder for 25+ years, and worked in semiconductor manufacturing 
for 10+ years,
and still things to learn.

Thanks all for the help. Can I have some catsup for my crow, please?

Bill
W1PA