[Elecraft] K2 Noise Solved

[Don Wilhelm]

Don,

I have a strong suspicion that the solder pad did not receive enough 
heat initially.  It can happen that the solder looks nice and shiny, but 
the solder does not have good flow onto the pad.  I have seen that 
condition more times than I would like.  It is the result of too low a 
soldering temperature.

A word to potential builders - keep the soldering iron temperature 
greater than 700 deg F (750 is better).  You will not damage anything if 
the soldering temperature is 800 deg F or below *and* the soldering time 
is kept short - contrary to popular belief, damage *will* occur with a 
low iron temperature applied for a long period of time.  Also use a 
small diameter solder so you can control the amount and watch as the 
thru-hole is heated, it will wick a bit of solder into the hole when it 
receives adequate heat, but too much applied solder will mask that 
process and can hide a bad solder joint.

73,
Don W3FPR

DDWEBB at aol.com wrote:
> A few weeks back I wrote that I was experiencing  a most unusual noise 
> problem. I had hoped that someone else might have had  the same problem and would 
> have the answer. This didn't happen.
> The  noise was noticeable when the volume control and RF Gain were at minimum 
> and  even the antenna disconnected.   
> I want to thank Gary,   KI4GGX, who was of great encouragement to me is the 
> solving of this problem. He  even suggested I record the noise.  I did and sent 
> it to him to hear.
> I  finally decided to use the bruit force approach and used a 1000 UF 
> capacitor  with one side grounded.
> Starting at U9 the audio amp, shorting leads to  ground through the 
> capacitor, I discovered the noise was coming in via the  CW side tone path. I traced 
> the noise to the input to U 10B pin 5.
> Under a  high intensity light and a magnifying glass, all solder pads looked 
> clean and  shiny.
> Not knowing where else to go, I resoldered all the pins of U10 plus  C36. I 
> suspect C36 may have been my problem but all that noise has now gone  away.
> Don Webb...KA7L  
>
>   
>