Dear Group:
I am about finished building my K2, but have encountered a frustrating
problem. Maybe someone can help me. I have performed most of the alignment
in Part III, but noticed the following when trying to receive signals:
When I turn the tuning knob, tuning is nonlinear. On some bands, it will
change frequency gradually, as it should, but then jump to another frequency.
On other bands, it never tunes linear at all, but just makes large jumps in
frequency as you are turning the knob.
I checked this jump, and sure enough, it was 5 KHz. So the PLL is working
ok. The problem is the lower bits of resolution that are processed by U5 (the
DAC) on the RF Board. On two of the bands, as the knob is turned, the output
of U5 (pin 7) varies from 0 to about 0.8 volts, then jumps to 4.0 volts. On
one or two other bands, it just jumps the 5 KHz -- no linear parts. And on the
other bands, the output of the DAC does not change at all that I can tell.
I checked the output of the encoder, and it seems to be working -- at least,
digital levels are sent to the microprocessor U6 on the control board. I don't
know if there's something messed up in the EEPROM or the DAC or the programming
of the microprocessor.
Have any of you had this problem or have suggestions?
Thanks for your assistance,
Norm
KE0ZT
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