I'm building K2 #5290. Have made it through the second session on the
RF board (Assembly Part II). The VCO freq is wrong....
The PLL Ref Osc range is 12098 to 12084. I'm seeing a stable 12445 on
the VCO (TP1), VFO set for 4000.1.
I've eyeballed the RF board carefully with a magifying lens & didn't
find anything conclusive. I looked at U4 with a scope and am not sure
if I'm seeing my bug, have my setup wrong, or the voltage chart is wrong.
U4 pin 5 (SDO) is zero and goes high (+5) with pulses on band +/-
(measurement chart says +5)
U4 pin 7 (SCK) is +5 and goes low with pulses on band +/- (measurement
chart says 0)
Given that the MCU can 'move' the PLL Ref Osc, that pretty well says
that the SDO and SCK lines are OK, right?
All the rest of the pins on U4 look reasonable per the measurement chart.
I've double checked L30, T5, D23-D26
I suspect I'm barking up the wrong tree with the SDO and SCK lines...
Where next?
Thanks! 73, Bill N2BC
PS: My first big kit was an SB-100 in 1965 I think. It's first power
on was much more dramatic than the K2. Smoke curling up from the
chassis. A hunk of miniature coax carrying low B+ was shorted. That's
when I figured my homebrew power supply should probably have some fuses....
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