No power output K2 Part III of assembly

[W7is]

I completed assembly of the K2 all the way through Part II testing and
everything came  up perfectly.   With the 40M SG2 sig gen I  got a perfect
S9 receive with the gen set to  50uv and very good  sensitivity of S2
on the 1uv gen output.   A really hot receiver and all tests  came up
perfecty.
 
Then I finished the assembly Part III, taking great care for the placement  of
all parts.  With special care to be sure the toroids were  done correctly.
  When I went to the final test and alignment Part III,  to  my
disappointment there was no power output on any band and the 40M  receive
had dropped from S9 to S5 when using the Sg2 sig gen on 50uv output.
There is 250ma receive and 440ma  xmit but no power output into a
50R dummy load.    The xmit tune 440ma xmit dosnt change at any  power
control setting.  
 
Receive alignment works on all bands 80 through 10M ...   except  for the
reduced
sensitivity after I completed Part III.     So  whatever is wrong is loading
down
the receiver on all bands.   Instead of S9 on 50Uv output from  the sig gen I
get S5 and no power out on any band.  

Unfortunately I wont be able to spend anymore time working on it  during
the next 3 weeks.   I spent a lot of tedious time being sure  everything was
assembled perfectly.   So its very unlikely to be a parts  placement
or soldering problem.    
 
Has anyone seen this sort of thing before?
 
Frank W7IS  
 
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Wilhelm-3]

Frank,

It is unlikely that the transmit problem and the receive problem are
directly related, but it is possible.

I suggest that you ignore the receive problem until you resolve the lack of
transmit - if they turn out to be related, the receive problem will also be
fixed.

On the transmit problem, first check to see if the fragile glass diode on
the bottom of the RF Board is still a diode - it may have been cracked
during assembly.

If the diode is good, and transmit problems still exist, use the RF Probe
(parts were shipped with the K2 kit), set the K2 power at 5 watts and turn
to Appendix E page 14 in the manual.  Starting halfway down the first
column, check the RF Voltages (during a TUNE) at the points listed.  If the
RF Voltage at a point is as high or higher than that listed, move on to the
next point until you find out where the RF signal is getting lost.  If the
RF Voltages at the Xmit Mixer is less than the value shown, stop and go back
to the start of the Transmitter section on page 12 and do all the steps from
th ebeginning until you find the problem.

Once you locate the failing stage, we can help further if the bad component
is not immediately obvious.

73,
Don W3FPR

> -----Original Message-----
>
> I completed assembly of the K2 all the way through Part II testing and
> everything came  up perfectly.   With the 40M SG2 sig gen I  got
> a perfect
> S9 receive with the gen set to  50uv and very good  sensitivity of S2
> on the 1uv gen output.   A really hot receiver and all tests  came up
> perfecty.
>
> Then I finished the assembly Part III, taking great care for the
> placement  of
> all parts.  With special care to be sure the toroids were  done
> correctly.
>   When I went to the final test and alignment Part III,  to  my
> disappointment there was no power output on any band and the 40M  receive
> had dropped from S9 to S5 when using the Sg2 sig gen on 50uv output.
> There is 250ma receive and 440ma  xmit but no power output into a
> 50R dummy load.    The xmit tune 440ma xmit dosnt change at any  power
> control setting.
>
> Receive alignment works on all bands 80 through 10M ...   except  for the
> reduced
> sensitivity after I completed Part III.     So  whatever is wrong
> is loading
> down
> the receiver on all bands.   Instead of S9 on 50Uv output from
> the sig gen I
> get S5 and no power out on any band.
>
> Unfortunately I wont be able to spend anymore time working on it  during
> the next 3 weeks.   I spent a lot of tedious time being sure
> everything was
> assembled perfectly.   So its very unlikely to be a parts  placement
> or soldering problem.
>
> Has anyone seen this sort of thing before?
>
> Frank W7IS
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com