Posted by
K2bew on
Jan 23, 2019; 2:57am
URL: http://elecraft.85.s1.nabble.com/K2-VCO-Alignment-T5-L30-tp7648249p7648415.html
Don Et Al,
So, It is with some embarrassment, and much relief, that I can report it
was operator error and my BFO is now working perfectly.
I got home from work and was getting ready to do some continuity checks to
all the circuits surrounding and including U11, but decided I better check
all the components again in that section with the RF board disconnected and
out of the case.
I found much to my chagrin I had not installed D37 and D38! I had them
checked off in the manual as being installed, and I even wrote in pencil in
the margin on the next step where you put the rest of the V149's in the RF
board that I had 2 left over, but I failed to notice I had them left over
because I did not put them in the step before!, good grief.
Anyway I have a high BFO reading of 4917.60 and a low reading of 4911.98
with a difference of 5.62.
Thank you Don and to others that gave suggestions, and I do wish those
having similar problems well in their trouble shooting.
Upward and onward 73,
Tom Bewick, K2BEW
On Sun, Jan 20, 2019 at 8:22 AM Don Wilhelm <
[hidden email]> wrote:
> Tom,
>
> Good work on the VFO.
> Before you replace U11, measure the resistance from the wire on the
> carrier board to the lead of the SMD IC. Do that for all pins. The PC
> traces on the carrier board are not thru-plated holes and sometimes
> become damaged with soldering.
>
> 73,
> Don W3FPR
>
> On 1/19/2019 6:35 PM, K2bew wrote:
> > Don et al,
> >
> > I tried a 15pf cap ( what I had on hand) at the source of Q19 to
> > ground and I got .025v on R30 that did not change with the adjustment
> > of L30, essentially no voltage.
> > So, I took it off and it went back to 4.5 volts. So, then I tried
> > Vicenç, EA3ADV's suggestion and I put 17 turns on the red wire of T5.
> > That got me a voltage of 8.5V on R30 with L30 bottomed out that I
> > was able to easily back off to a stable 6 volts.
> > I went ahead and did the voltage tests on the other bands and had a
> > nice range of 1.844 to 6 volts as my low and high on the VCO.
> > So, that's all set.
> >
> > However, new problem. I went on to the test the BFO and I have 0000.04
> > kHz. on TP2, so it's not working.
> > I went to the trouble shooting guide and I have 0.058 Vrms on pin 6 of
> > U11 with the RF probe.
> > Looking at the archives of the reflector that would indicate that U11
> > is bad and I need a replacement, correct? or are there other things I
> > should look at first?
> > The good thing is I'm becoming very accustomed to the radio and
> > enjoying the trouble shooting.
> > Thanks for all the help, I really appreciate it.
> >
> > 73,
> > Tom Bewick, K2BEW
> >
>
>
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