[K2] VCO Test

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[K2] VCO Test

Clark Ward Jr
I got discouraged after having more than a few issues with my K2 and
have returned to finish the project now that I'm not eyeballs-deep in
nursing school.

I'm in 'Alignment and Test, Part II' in the VCO Test.  Everything is
good up through this point (Having started anew, I reperformed all
calibration and alignment steps up to this point).

I have the frequency probe plugged into P6, and TP-1, the VFO set to
4000.10 kHz, and used the menu to have the freq counter active.

The display shows zeroes all the way across, where it should show
something between 8 and 10 MHz.  Any guidance on places to look is
gratefully accepted.

--
KI4GYT Clark in Georgia
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Re: [K2] VCO Test

Don Wilhelm-4
Clark,

You either have a non-functioning VFO, or you have something wrong with
your probe (or Q9/Q10 on the Control Board).
Try the probe in TP2 to see if you get a frequency displayed - if you
do, you likely have a VFO problem - first place to check is T5 - make
certain the leads are well stripped and tinned, you should have a bit of
tinned wire on the top of the board.  Examine the winding carefully, if
you wound the green wire in the wrong direction, the VFO will not work.  
If you have the wrong number of turns, it may be off frequency enough
that the PLL will not lock in.  When counting toroid turns, count the
number of times the wire passes through the center of the core.  A
straight wire through the center is one turn, a full wrap around the
core is two turns.

There are a lot of "ifs" in the above statement, but take them into
consideration and get back with us if you do not find the problem.

73,
Don W3FPR

Clark Ward Jr wrote:

> I got discouraged after having more than a few issues with my K2 and
> have returned to finish the project now that I'm not eyeballs-deep in
> nursing school.
>
> I'm in 'Alignment and Test, Part II' in the VCO Test.  Everything is
> good up through this point (Having started anew, I reperformed all
> calibration and alignment steps up to this point).
>
> I have the frequency probe plugged into P6, and TP-1, the VFO set to
> 4000.10 kHz, and used the menu to have the freq counter active.
>
> The display shows zeroes all the way across, where it should show
> something between 8 and 10 MHz.  Any guidance on places to look is
> gratefully accepted.
>
>  
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Re: [K2] VCO Test

k6dgw
In reply to this post by Clark Ward Jr
Clark Ward Jr wrote:

> I have the frequency probe plugged into P6, and TP-1, the VFO set to
> 4000.10 kHz, and used the menu to have the freq counter active.

FWIW:  My K2 [#4398] had a similar problem a number of years ago.
Initially in the alignment process it seemed to be working, but then I
got the "not on 40m" message [232?].  It turned out that the
preamplifier transistors in the freq counter assembly were defective.
They worked at the lower frequencies of the initial alignment, but had
no gain at the higher frequencies.  Elecraft replaced them right away
with new ones.  Forgive my memory and I'm colorblind but I think the bad
ones had a blue flat face, or so I was told.

Just a shot in the dark.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2010 Cal QSO Party 2-3 Oct 2010
- www.cqp.org
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