K2 #4830 IS ALIVE

[Ken Wagner K3IU]

Hi Gang:

Finished up the basic K2 (S/N 4830) this afternoon with no problems except
for the VCO range which was below minimums. Fortunately, I had a 12uH
inductor for L31 from an earlier project so that went in and solved the
problem.

Still have a couple of boxes of options to get assembled. Much fun ahead!!

73,

Ken K3IU

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[Mike Markowski]

Good going, Ken!  Can't wait till I'm saying the same about #4834.

I've noticed a few notes regarding L31, and I'm not at that point yet in
my K2 build.  It seems the concensus is that 12 uH should be used rather
than 10 uH in the notes I've read, so I wonder why the kitted component
was changed.  Any recommendations on whether or should use 12 uH from
the start or better to try the supplied one first?

Thanks,
Mike  AB3AP
Avondale, PA

Ken K3IU wrote on 03/23/05 19:13 ET:

> Hi Gang:
>
> Finished up the basic K2 (S/N 4830) this afternoon with no problems except
> for the VCO range which was below minimums. Fortunately, I had a 12uH
> inductor for L31 from an earlier project so that went in and solved the
> problem.
>
> Still have a couple of boxes of options to get assembled. Much fun ahead!!
>
> 73,
>
> Ken K3IU

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[Ken Wagner K3IU]

Hi Mike:

Well, I don't know what the statistics are on the batch of crystals that are
being shipped, but I'd give the 10uH a try and see what you get. All you
need is 9.8. I had 9.5 and someone else I know had 9.7. However, I'd bet
that there are numerous K2s out there that came in >= 9.8. So.... I'd
recommend installing what you have. If it doesn't quite make the grade, than
you can get a 12 uH from Elecraft. In the meantime, the marginal range
should probably work until you get the replacement from Elecraft. It is easy
to replace, but don't forget that you'll have to run CAL PLL after you put
the new one in and then re-do the CAL FIL after the CAL PLL.

GOOD LUCK & Have Fun!!!

73,
Ken K3IU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mike Markowski
Sent: Thursday, March 24, 2005 9:40 AM
To: [hidden email]
Subject: Re: [Elecraft] L31 10 uH vs 12 uH (was: K2 #4830 IS ALIVE)

Good going, Ken!  Can't wait till I'm saying the same about #4834.

I've noticed a few notes regarding L31, and I'm not at that point yet in my
K2 build.  It seems the concensus is that 12 uH should be used rather than
10 uH in the notes I've read, so I wonder why the kitted component was
changed.  Any recommendations on whether or should use 12 uH from the start
or better to try the supplied one first?

Thanks,
Mike  AB3AP
Avondale, PA

Ken K3IU wrote on 03/23/05 19:13 ET:
> Hi Gang:
>
> Finished up the basic K2 (S/N 4830) this afternoon with no problems
> except for the VCO range which was below minimums. Fortunately, I had
> a 12uH inductor for L31 from an earlier project so that went in and
> solved the problem.


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[George Cortez Jr]

Hi
 I checked all you said and the voltage still wont move
I ohmed the t5 out and its about 350ohm across from 1-2 to 3-4
all else looks good. 80&40 are the same voltage
20/17 are under 4.5v 15 is the same as 80/40 abt 7.95v
12/10 under 5.5v I think t5 will have to be rewound?
What do you think?

George





....................................................................

Hi George:

To get a 12 uH L31, get in touch with Gary, or Parts, or Support at
Elecraft. I'm sure they will ship you one out right away. Here is quote from
an email I got from Gary about this issue: "We are in the process of
switching over to the 12uH choke until the current lot of PLL crystals is
used up. Most of them so far have shown slightly lower than needed range
with the 10uH choke."

The most probable cause of being unable to adjust the VCO voltage with L30,
assuming correct installation of T5, L30, C72, and the PLL temp comp board,
is having the 1-2 (red wire) windings on T5 too bunched up. Check that they
are spread out around the 'roid like shown in the picture. You don't need to
uninstall T5 to do this... Just use the green tuning stick that comes with
the K2 to slide the windings on the 'roid. If there is no voltage change at
all when you adjust L30 (also change bands to see if the voltage is
different on another band), then you need to check for a short, solder
bridge on or in the vicinity of the l'il PLL temp compensation board that
you put together. It is very easy to create a l'il solder bridge or short on
that l'il guy.

Good Luck!!!

73,
Ken K3IU

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[Ken Wagner K3IU]

Hello again George:

I just measured the resistance from the 1-2 side of T5 to the 3-4 side and
got about 340 ohms. I'm not sure what that means, though, other than giving
you a point or reference<g>.

You should be able to tell if you have wound T5 correctly without removing
it. Just look at the picture in the manual to check for winding directions
and then count the turns and check that the correct color wire is going into
the correct numbered hole.  

Before you do that, though, check that the two different kinds of varactors
(MV209 and 1SV149) are installed in the correct locations. When you are
confident of that, then I would look for a problem with the PLL temp
compensation board.

And not trying to put you off... REALLY... But that about runs the limit of
my ability to help other than to repeat the mantra of check soldering, check
soldering, check soldering and then once again check soldering.

Hope I haven't muddied the waters for you George. I'm not an EE or
technician.... Just been messing with the K2s for a couple of years<g>.

Good Luck!!

73,
Ken K3IU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of George Cortez
Sent: Saturday, March 26, 2005 5:02 PM
To: elecraft list
Subject: RE: [Elecraft] K2 #4830 IS ALIVE

Hi
 I checked all you said and the voltage still wont move I ohmed the t5 out
and its about 350ohm across from 1-2 to 3-4 all else looks good. 80&40 are
the same voltage
20/17 are under 4.5v 15 is the same as 80/40 abt 7.95v 12/10 under 5.5v I
think t5 will have to be rewound?
What do you think?

George





....................................................................

Hi George:

To get a 12 uH L31, get in touch with Gary, or Parts, or Support at
Elecraft. I'm sure they will ship you one out right away. Here is quote from
an email I got from Gary about this issue: "We are in the process of
switching over to the 12uH choke until the current lot of PLL crystals is
used up. Most of them so far have shown slightly lower than needed range
with the 10uH choke."

The most probable cause of being unable to adjust the VCO voltage with L30,
assuming correct installation of T5, L30, C72, and the PLL temp comp board,
is having the 1-2 (red wire) windings on T5 too bunched up. Check that they
are spread out around the 'roid like shown in the picture. You don't need to
uninstall T5 to do this... Just use the green tuning stick that comes with
the K2 to slide the windings on the 'roid. If there is no voltage change at
all when you adjust L30 (also change bands to see if the voltage is
different on another band), then you need to check for a short, solder
bridge on or in the vicinity of the l'il PLL temp compensation board that
you put together. It is very easy to create a l'il solder bridge or short on
that l'il guy.

Good Luck!!!

73,
Ken K3IU

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[Don Wilhelm-3]

George,

Do 2 things before rewinding T5:

1) check T5 visually and count the turns - the direction of the turns should
look like the illustration in the manual - and you did wind it on the yellow
core did you not?
2) Measure the frequency that is being produced on the low end of each band
(use CAL FCTR with the probe in TP1) - compare it to the chart on the manual
page just before the schematics.  If not correct, tell us what frequency you
measured for each band.

73,
Don W3FPR

> -----Original Message-----
> Hi
>  I checked all you said and the voltage still wont move
> I ohmed the t5 out and its about 350ohm across from 1-2 to 3-4
> all else looks good. 80&40 are the same voltage
> 20/17 are under 4.5v 15 is the same as 80/40 abt 7.95v
> 12/10 under 5.5v I think t5 will have to be rewound?
> What do you think?
>
> George
>
>

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