On Wed, 3 Feb 2010, Don Wilhelm wrote:
So the problem is that the BFO is not oscillating.
Searching some more, I am no longer certain that this is the case, I have
been using a Fluke 77 for AC voltage measurements. Checking the spec
sheet, it appears thaat AC voltages are measured from 100mV to
Conway,
If you have an oscilloscope, dragging it out is *not* overkill - it will
show you the peak to peak RF voltages as well as the waveform.
Lacking the 'scope, you can build up the RF Probe - the parts are
supplied with the K2 kit and the circuit board is part of the 'switch
spacing tool'.
expected - Q24 does not pass the BFO signal on receive due to the
absence of voltage on the VALC signal line.
Thats it! Your clue led me to trace V_{alc} back to the control board.
I NEVER had a non-zero measurement on V_{alc} even though I was in CAL
FCTR.
It turns out that I forgot to
Conway,
It is great news that you have found the source of the problem.
Onward to the rest of the K2 build, and I wish you no more unsoldered pins.
73,
Don W3FPR
Conway Yee wrote:
expected - Q24 does not pass the BFO signal on receive due to the
absence of voltage on the VALC signal line.
Does your counter probe report a frequency reading when plugged into
TP1? If so, the probe is working, if not, then your problem is with
either the probe itself or the Q9 and Q10 circuits on the Control Board.
The frequency probe is fine.
TP3 shows 12099.11
when I switch to TP2, I read zero.
Conway,
The DC Voltages are OK - even for Q24. Recall that I asked you to
measure while in CAL FCTR. That places a voltage on the VALC signal
line. It normally is used for power control and is developed on the
Control Board at Q8.
So the problem is that the BFO is not oscillating. First
Conway,
Does your counter probe report a frequency reading when plugged into
TP1? If so, the probe is working, if not, then your problem is with
either the probe itself or the Q9 and Q10 circuits on the Control Board.
If (and only if) the probe works in TP1, then do the following -
otherwise
TP2 reads 0 MHz.
Checking the components involving the BFO, No obvious missing components.
No obvious cold joints.
I checked the to pads adjacent to L33 which I believe to be the pads to
the BFO crystal filters (two more are hidden under L33). With power on,
the voltages are different making me
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