[Elecraft] K2 PA repair kit

[Don Wilhelm]

Jerry,

I really don't know how/where you got those bits of information from the 
archives - because it is definitely not correct.

That is a 1.5 ohm resistor (1/2 watt) included with the kit and is to 
replace the emitter resistor of Q6 if needed - so check while you have 
the rear cover/heat-sink removed.  If R50 is a 1/4 watt resistor, 
replace it with the 1/2 watt - if it is already a 1/2 watt, check to see 
if it is open - if so, replace it with the new one.  If neither of these 
conditions apply, you have a 1.5 ohm resistor for your junk box.

No need to remove T3 - that is simply one technique to remove the 
voltage from the collectors of Q7 and Q8 while troubleshooting the 
problem, but since you will be removing Q7 and Q8, there is no need to 
do anything with T3, just leave it in place.

Be careful when removing components not to damage the thru-plated 
holes.  If you do not have good de-soldering tools, cut the leads off 
the components and remove them from the holes one lead at a time - clean 
up the holes with solder wick, or if necessary a stainless steel needle 
or a wooden toothpick pushed into the hole while the solder is molten 
will clean them nicely.

Before replacing Q7 and Q8, replace Q11 and Q13 - then with Q7 and Q8 
removed, measure the DC voltage at the base of Q7 and Q8 during a TUNE 
operation.  If the voltage is 0.60 to 0.63 volts, all is OK, but if not 
find the problem with the Q11,Q13 bias circuit before proceeding.

When that is done, solder in the new Q7 and Q8, put the heat sink back 
on and try transmitting.  DO NOT attempt to transmit without the heat 
sink on Q7 and Q8 - if you do, they will only last a couple seconds.

73,
Don W3FPR.

n0jrn wrote:
> Gang:             Got the repair kit in the mail yesterday for my K2.   ( 
> Thanks Elecraft for the speedy delivery )     I see a 15 ohm resistor in the 
> kit and I'm curious what that is for.
>
> Researching the archives tells me that's to be install for troubleshooting 
> if I pull T3 from the board but wanted to be sure before proceeding.
>
> IF  that's the case,   is it installed as a jumper between the base of Q7 & 
> Q8 ???
>
> Thanks and enjoy the game:     ( if your a football fan )
>
> 73     Jerry          N0JRN 
>   
>