[Elecraft] Problem with KAT2 Bridge Null Adjustment

[Don Wilhelm]

Ted,

You will find the problem is with T1.  It must be wound and installed 
exactly as shown in the manual, and that includes the direction of the 
winding.

Your K2 is likely putting out all the power it is capable of, so do 
those TUNEs for only a short period or you will be replacing the PA 
transistors.

73,
Don W3FPR

On 5/7/2016 12:02 PM, Dauer, Edward wrote:
> Advice requested for the following problem:
>
> Completed and installed the KIO2.  That works fine, so far as it has been tested with the outboard ("twins") KPA100 and KAT100.  Next step was to put the amp and high power tuner aside and install a KAT2 in the base K2.  [In case it matters, the K2 does not have the battery option.]
>
> All went well with the KAT2 until the Bridge Null Adjustment.  There are two strange symptoms:
>
> First, adjusting C55 has no effect, and the display does not behave as it should.  When Tune is held, the display first says HiCur, then it quickly changes to ATU and then, again quickly, it changes to 000 and stays there.  Adjusting C55 to every possible position changes nothing.  Each try produces the same display:  about 2 seconds of HiCur, two seconds of ATU and then 000.
>
> Second, the DC voltage at pin 1 of U4 is way off.  In Receive Mode it reads 0.0, as it should.  But in Tune mode, at 5 watts indicated, it reads only 0.69 DCV rather than the 3.0 to 4.0 expected.
>
> I haven't put an external power meter on the rig yet but a 15-watt dummy load gets warm after a while so there does seem to be RF output.
>
> I see no solder bridges, no cold joints, no breaks or shorts thatI can see.  The plugs and sockets have been checked at least five times to assure they are properly aligned and properly assigned.
>
> Any ideas, anyone?  Thanks!
>
> Ted, KN1CBR
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