[Elecraft] K1 still with no output on 20m

[Don Wilhelm]

David,

You are in for a bit of Transmit Signal Tracing to localize the problem 
further.
Yes, it is likely to be on the Filter board, but there are 4 main parts 
of the filter board.
1) The crystal oscillator
2) The Pre Mixer bandpass filter
3) The RF Bandpass Filter
4) The Low Pass Filter.

Turn your manual to the back and go through the steps in the Transmit 
Signal Tracing section to find the stage where the signal RF Voltage is 
substantially less than the expected values -  ignore those that are 
greater than the expected values.

You will need an RF Probe (schematic in the manual if you don't have 
one) or a 'scope with a 10X probe.  If you use a 'scope, multiply the 
expected values by 2.8 to obtain the peak to peak values you will see on 
the 'scope.

73,
Don W3FPR

On 3/18/2013 9:05 PM, David L DuPuy wrote:
> Don,  I appreciate your help.  I have the two-band filter board.  40m is
> doing just great. I just had a great QSO and good signal report on 40.
>
> I pulled the filter board and checked every single capacitor in the Band 2
> string, and all are the correct values.  One minor deviation is that C18
> calls for a value of 2.7 or 3.0 pF, and the only supplied capacitor I had
> close to that was 2.2 pF...  so I don't think that's the problem.
>
> I tried to tell if the three relays were switching bands by placing my
> finger on them, but I couldn't feel anything.  I hear a distinct click but
> don't know if all three are firing.  The coil pins are hard to reach from
> the top of the board, but maybe I'll try that next.  I also checked the
> continuity of all of the inductors and I checked it on the next pc board
> joint, i.e., not on the end of the wire.  Can't find any problems.  Sigh.
>   I also examined all of the soldered connections carefully with a good
> quality magnifying glass... can't find anything suspicious.  All three
> relays read 250 ohms across the coils.
>
> I am peaking the inductors by watching the S-meter on my FT-950, and I can
> clearly see the signal peaking.  I'm sending the K1 to a dummy load with no
> tuner.  The 20m band can now be set to indicate 5 watts, but there's
> essentially no output.  I'm almost out of ideas!  Any suggestions are most
> welcome.  David  AC4BN
>