[Elecraft] K2 RF board resistance check - RYCOM

[Charles Vollum]

Masleid, Michael A. wrote:

> Next thing to do is put a bright light behind the board and a good 
> magnifying
> glass on your side and look for little solder wiskers or debris 
> anywhere along
> the trace.

So far, I see nothing that could cause this.  The trace has only 2 
sections, both are clean and clear. The only places I couldn't inspect 
visually were on the top side under the U1 socket and under the K10.

> If nothing shows up, there are ways to inject current into the trace 
> and see
> where it goes.  I just measure resistance to ground along the trace.  
> It will
> be lower at the end close to the short.

The resistance was about 0.1 ohm less at the relay end than at the U1 
end, so I started there.  In the end, I desoldered K10 (I hope it 
wasn't damaged in the process... looks OK, anyway.)  This didn't change 
any resistance readings, but allowed inspection of the top side of the 
PCB under K10, which appears fine to me.

I'm not looking forward to trying the same thing with the U1 socket, 
however.  I think the difficulty of component removal goes up 
exponentially with the number of pins!

I think I'll sleep on it, and look again tomorrow.  Any further ideas 
would be appreciated.

Charles N7BPT

ps -- although it doesn't seem to be part of my problem, I'm still 
curious about RYCOM.  It can't just float, and the 160 board can't be 
the source for it, but I still haven't found where it comes from.  Can 
anyone direct me to the right part of the schematic?  I signal index 
would be useful for this kind of stuff.
----
Charles Vollum
http://xsw.com/boojum -- Boojum, a trailerable offshore tug yacht