[Elecraft] K2: Flakey PA Output

[Don Wilhelm]

Clark,

Intermittent operation does usually mean a marginal solder connection - 
particularly those that might have a heat characteristic to them.
Q6 is quite husky, so I would not suspect the device itself.  Check R50 
for good soldering, also look at the schematic Sheet 4 of the RF Board 
to identify the other components associated with Q6.  How is the tinning 
of the red leads on T2?  The Green leads of T1?
Q10 and R46, R47, R48 are also suspects.

73,
Don W3FPR

Clark Macaulay KE4RQ wrote:
> Was operating the ARRL CW contest and output on my K2 QRP rig dropped to
> zero.  Bummer. Anyway, I took it to the bench and started to check it out
> when it began to work.  Put it back together and took it to the operation
> position and it failed. I'm thinking a cold solder joint or something.  
>
> Tonight I stared signal tracing and found the output of Q6 to be zero under
> key down after a few seconds.  I as about to order a new Q6 and it started
> working again.  I've been poking around, pushing this component and that
> one, hoping to find an intermittent but with no success.
>
> Could Q6 be failing internally--that is the little beastie is going bad not
> because of a solder joint (which I have reheated) but because of something
> inside?  Is there another component in the driver circuitry or PA that could
> be causing this?  
>
> I really wanted to use the K2 this weekend for the QRPARCI contest but may
> have to rein in my big rig.  
>   
>