[Elecraft] K2 transmitter alignment problems

[Don Wilhelm]

Dan,

Did you find a peak on each of the bandpass filter tuning steps?  If 
not, go back and align the bandpass filters.  Set the power anywhere 
between 1.5 and 2 watts.  Keep the power low (less than 5 watts) and you 
can find the peak more easily.  When the power climbs (it will if the 
tuning was not 'right on'), exit tune and re-enter again to reduce the 
power.

With the bandpass filters peaked for certain, check the power out at the 
10 watt setting - if there is still a problem, go on to the next checks.

You may have one too many turns on some of the LPF toroids - that would 
explain 80 meters and 17 meters, but not 15, so check the values of C118 
thru C122 as well - on the toroids, count the number of times the wire 
passes through the center of the core.

Check T4 - the "link" wires should go straight through the hole in the 
core, they do not go through both holes.  Be certain Z1 and Z2 are in 
place and properly soldered.

If all that is good and the problem persists, report back, but this time 
do the power out check only at 10 watts and also tap display and note 
the current draw.  Depending on the results of that report, you may have 
to do some Transmit Signal Tracing, so build up the RF Probe from the 
parts provided with the K2 kit unless you have access to a 60+ MHz 
oscilloscope with a 10X probe of equal or greater frequency rating.

73,
Don W3FPR


Dan Grizzard wrote:
> Hello all,
> I have finally gotten to the final alignment portion of my K2 and have found power out problems on 3 bands, 80, 15, and 17 meters. The measurements follow:
>
> Band:        2 watts setting           5 watts setting         10 watts setting
>
> 80 m.         2.0watts  out            1.8 watts  out             1.8 watts out
> 20 m.         2.0 watts  out           5.4 watts out              10.7 watts out
> 30 m.     .   2.5 out                       5.8 out                        10.6 out
> 20 m.         2.3 out                       5.3 out                        10.6 out
> 15 m.         2.0 out                       1.9 out                         1.9 out
> 17 m.         2.0 out                       3.9 out                          4.0 out
> 10 m.         2.2 out                      5.2 out                         10.2 out
> 12 m.         2.0 out                      5.2 out                        10.3 out
>
> All power at the 2 watt output setting was adjustable at the designated pots or capacitors. 
> The rig had 13 vdc input and transmitting into a 50 ohm dummy load.
> Looking forward to suggestions.
> 73
> Dan
> af4lb
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