YouKits TJ2B, Руководство по монтажу

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Tj2B is used with the advanced DDS as LO, the frequency is accurate, rock-stable; the
signal pure and clean, the tuning fast and smooth. However, the the accuracy of the
DDS depends on the precise calibration of the DDS clock. A good frequency counter is
required for this process.
After the clock calibration is saved, tune the frequency to the highest frequency of band 2
to see if the the frequency is still accurate. For Kit A the highest frequency is 18.199999.
The frequency counter reading should be 27.199999. If it is lower than this, you have to
calibrate the clock again: decrease the clock 10 or 100Hz for a try. Repeat the process
until both the lowest and highest frequencies are 12.000000 and 27.199999 respectively.
With 8-digit frequency counter it is not easy to find the small frequency error at the
calibration stage. The frequency counter displays 11.999999. It seems that an increase or
decrease of 10Hz in clock does not affect the "Hz" reading. In reality does. The small
error becomes bigger as the frequency increases.
After the DDS calibration, please calibrate the BFO. Refer to "Calibrating BFO" for
details.
Important: The accuracy of the DDS and BFO depends heavily on the accuracy of your
frequency counter. If your frequency counter is not accurate, your TJ2B's frequency will
not be very accurate, but this would not degrade the performance of the kit except for the
50 - 100Hz display error.