http://elecraft.85.s1.nabble.com/K2-Can-t-get-frequency-counter-to-work-on-TP2-tp392499p392501.html
You are a genius! Thanks your suggestion worked. I replaced Q9/Q10
with spare 2N2222s and the counter started working again. Thank you!
> Carroll,
>
> Unless you are using someone else's email, it is neat to know that there is
> another Wilhelm in the K2 family - I started with SN 20 and it is still
> going strong.
>
> If your RF Probe is anywhere near correct, it would seem that you have
> plenty of RF signal at TP2, so the problem must be in the counter itself.
> In the long past, there were problems with the gain of the 2N5179
> transistors Q9 and Q10 on the control board - we thought that problem had
> been squashed, but perhaps it has reared its ugly head again. As a side
> note, I had purchased some stock 2N5179 transistors, (Fairchild
> manufacture), and found that they do not work well in the counter input
> circuit either, so that circuit is evidently sensitive to the transistor
> type and one 2N5179 is not necessarily like another for that application.
>
> If you have some 2N2222s around your workbench, try replacing the 2N5179s
> with 2N2222s. The counter high frequency limit may be reduced a bit, but if
> it is only used internally in the K2, the 40 MHz limit is not required, the
> highest frequency needed is less than 25 MHz. Contact
[hidden email]
> and I am certain you can have replacement transistors on their way to you.
>
> Just a side note - in your measurements of RF Voltage at Q24, it would seem
> that you crossed the gate and drain voltages. Check the lead orientation on
> the K2 schematic key and let us know if there was no typo. If you are truly
> getting RF Voltage on the drain, Q24 may be the problem (but then the K2
> would have no transmit output in that case)
>
> 73,
> Don W3FPR
>
>
> > -----Original Message-----
> >
> > 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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