[Elecraft] K2 DOA at second power up test

[Don Wilhelm]

Sorry for my oversight - It did hit me that you only had the receiver 
section built.

Can you follow on the schematic?  I doubt the fuse is faulty - it is 
probably working just fine and opens because there is more than 5 amps 
of current - it does act rather fast.

Can you follow along in the schematic?  chasing the source down will be 
easier and make more sense if you can.
I suggest you measure the resistance of the 12 volt line - it will 
probably be close to zero.
Then start lifting one end of selected components to isolate each stage 
that uses 12 volts.  Stop when the resistance on the 12 volt line goes 
up - you have found the troublesome stage.
I would start with lifting one end of RFC11 (that is the toroid on the 
bottom) to remove the Post-Mixer Amp.
Then lift one end of R74 to remove the Preamp.
Then lift one end of R97 to remove the TX Buffer.
The last component is regulator U2 which feeds the IO Controller.

That should be all the stages that you have built at this point which 
draw directly on the 12 volt line (other than the regulators on the 
Control Board.

73,
Don W3FPR

On 11/7/2011 5:53 PM, ke4d wrote:
> Thanks Don, Elecraft told me the same thing. However, as I told them, I'm on
> the second power up test in the manual, there is no T3 or PA transistor in
> on the board at this time.  I've built the front panel, the control board
> and the receiver, no transmitter yet. I'm pretty sure its something in the
> 12v line, I just can't find it. I wondered about F1 but I show 12 volts on
> both sides of it so I guess its ok. And the power supply is fine, I have 12
> volts on the RF board until I push the on switch on my front panel. Then the
> voltage drops to about 2.5.  I figure something is pulling it down, I just
> need to find it!  Thats what I get for building when I have to have my
> magnifying glasses on the see anything on those boards!
>
>