Posted by
Spence Wilhelm-2 on
Jul 27, 2006; 10:03pm
URL: http://elecraft.85.s1.nabble.com/K2-Can-t-get-frequency-counter-to-work-on-TP2-tp392499.html
Hi,
I finished construction of my K2 (serial #5400) last month and all was
working well. At the time of construction all of the filter alignment went
well. It has been lots of fun... I'm selling my Yaesu. :-)
Since then I decided to calibrate the VFO on my K2 to get the frequency
better aligned. I don't have an accurate frequency generator so followed
the instructions in the manual and used WWV as my source. That all went
fine but when I went into Cal Fil and wanted to make a change to one of the
filters got an 'info 230' message. I searched the list and found that was
related to the microprocessor not seeing the BFO frequency during a CAL
FIL. I verified that the frequency probe works by doing a CAL FCTR with the
probe on TP1. When I move it to TP2 it always shows 00000.00. When I first
aligned it last month it worked but not now.
So... I checked the following... I verified that Q24 is getting turned on
via V ALC when CAL FCTR is enabled. I see 7.26V DC when V ALC is on, zero
otherwise.
Used my RF probe to find the following RMS voltages for Q24.
V ALC On
Q24 drain 5.99 V
Q24 source 2.02 V
Q24 gate 0 V
V ALC off
Q24 drain 9 mv
Q24 source 15 mV
Q24 gate 0 V
It looks like the FET is turning on and off according to V ALC. I used my
scope to look at TP2 and can see a nicely formed wave form at around 4Mhz,
But can't detect it with the internal frequency counter and probe. So to
verify the probe and counter works I used the frequency probe to verify
04913.34 MHz on pin 6 of U11 but it shows 00000.00 when moved back to TP2
Really confusing...
Nothing jumps out at me. Its been years since I did any serious
troubleshooting. :-) Anybody have any ideas about what I can do?
73,
Carroll (W7CSW)
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