http://elecraft.85.s1.nabble.com/K2-VCO-Alignment-Issue-tp7651214p7651284.html
> Don,
>
> Finally got back to the K2 this afternoon. I have confirmed that T5 is
> on the yellow core, with 16 turns through the center on the red and 4
> turns on the green. I mentioned earlier that I got all the toroids
> from the Toroid Guy, so I felt confident that it was correctly wound.
> I checked all the relay pins on K13, K14, and K15 and did not see any
> solder bridges on any of them. Next, I pulled T5 and removed one turn
> and re-installed. Unfortunately, nothing has changed. I'm still
> getting that same 8.37 V at R30. Incidentally, I'm getting the 8.37 V
> on either side of R30. Is that normal? I can also pull T5 and wind a
> new one with the parts that came with the kit if you think that might
> help, but something tells me that the problem lies elsewhere. I also
> thought about pulling C72 and replacing it with another one, but
> unfortunately there was only one of that value in the kit and I don't
> have anything like it it my parts stash. Any new thoughts?
>
> de John, WB4GLJ
>
>
>
> On Sat, Apr 27, 2019 at 6:00 PM Don Wilhelm <
[hidden email]
> <mailto:
[hidden email]>> wrote:
>
> John,
>
> Both frequencies are too low.
> You have either too much capacitance or too much inductance in the
> VFO.
> Count the number of times the red wire goes through the center of
> the T5
> core - it should be 16.
>
> Check relays K13, K14 and K15 for solder bridges.
>
> Make sure the core of T5 is yellow.
> You might have to try removing a turn from T5 if you can find no
> other
> cause - there have been a few K2s in the long past where the
> permeability if the T5 core was higher than expected, and removing 1
> turn from T5 corrected things - I have not seen that recently, but
> I do
> mention it 'just in case'.
>
> If all else fails, you may have to "wind your way" through the relay
> connections for the VFO Range Select area using the Relay Table on
> the
> Schematic Key page as your guide for the paths through the relays.
>
> 73,
> Don W3FPR
>
> On 4/27/2019 5:37 PM, John Wingard wrote:
> > Hi Don,
> >
> > Thanks for the quick response. I did check C72 again. It is a 271
> > value. I then spread the red turns on T5 as far as I could. I'd say
> > they cover about 90+% of the toroid. I put the L30 slug at
> mid-point
> > of travel and measured voltage at R30 and it is still right at 8.37
> > V. While there I checked the frequency at TP1 and it was 8247.90,
> > which is considerably lower than the 8913 that you expected.
> >
> > Next I went up to 7100 and measured the voltage at R30. Still
> right at
> > 8.37 V, no change. Frequency at TP1 @ 7100 was 11558.11.
> >
> > So, it appears that the frequency at 4000 is not within the
> expected
> > range, and likely not at 7100 as well. Hope this tells you
> something
> > because I'm stumped.
> > I've got some plans for this evening so I may not get back on it
> until
> > tomorrow afternoon, but if you've got any more things for me to
> try I
> > will do them then.
> >
> > John, WB4GLJ
> >
> > On Sat, Apr 27, 2019 at 1:57 PM Don Wilhelm
> <
[hidden email] <mailto:
[hidden email]>
> > <mailto:
[hidden email] <mailto:
[hidden email]>>>
> wrote:
> >
> > John,
> >
> > That high voltage is trying to reduce the capacity of the
> varactors.
> > Which means there is either too much capacity or too much
> > inductance in
> > the circuit.
> >
> > Check the value of C72 first - it should be marked "271".
> Then set
> > the
> > L30 slug to about mid-position and spread the red turns of T5
> > enough so
> > the starting and ending turns are adjacent. What is the
> voltage when
> > tuned to 4000 kHz? Measure the frequency at TP1 - it should
> be near
> > 8913 kHz.
> >
> > Then change to 40 meters - 7100 kHz - What is the R30
> voltage and
> > what
> > is the VFO frequency measured at TP1.
> >
> > The answer to those questions will help in determining what
> to do
> > next.
> >
> > 73,
> > Don W3FPR
> >
> > On 4/27/2019 1:32 PM, John Wingard wrote:
> > > Working on my 2nd K2 (S/N 7869) and have run into a
> problem with
> > the VCO
> > > alignment. I'm getting a constant 8.37 V at R30 at 4.000 MHz..
> > I cannot
> > > change it with the full range of L30. Correct type inductor is
> > installed at
> > > L30. Dropping the VFO down to 3.500 doesn't change it
> either. I
> > have gone
> > > back through the archives and read just about every post
> > concerning this
> > > problem but nothing I have tried has made any difference.
> I have
> > double
> > > checked all correct parts placements and orientations,
> re-flowed all
> > > connections in the quadrant of the board around the VCO
> section.
> > T5 is
> > > wound as per the manual (from the Toroid Guy) and installed
> > correctly. I
> > > have tried both spreading and compressing the turns on T5 with
> > no change
> > > either way.
> > >
> > > Regarding the thermistor board, I have 4.18 V on pin 5 of U6.
> > >
> > > Test in the previous section were within specs:
> > >
> > > 4 MHz Oscillator Cal using CAL FCTR was 12099.61 and confirmed
> > with an
> > > external counter.
> > > Range of the PLL reference oscillator: 12099.61 - 12086.01 =
> > 13.59 kHz
> > > VCO oscillator test: 8162.60 MHz
> > >
> > > I'm about out of ideas at this point. What should I start
> > checking next?
> > >
> > > Thanks for any help!
> > >
> > > 73 de John, WB4GLJ
> > > ______________________________________________________________
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