K1 building problem - VFO not working

[Stan AE7UT]

Everything has checked out good so far.
When I went to the CAL - EDIT the display reads "OPF" and then back to "E42".
I'm assuming the VFO is not functioning.

I checked all the soldering and don't see any bridges or other problems.

Where do I go from here?

Thanks for any help you can be.

Stan AE7UT

[Stan AE7UT]

Oh one more thing.

The stand off post for the Front Panel Board was missing in the kit.
It should arrive in Monday's mail.
I just put it together WITHOUT this in place being careful not to
bend any pins because it's not 100% stable without it.
Would that effect the VFO?

Thanks
Stan AE7UT

[Stan AE7UT]

For those of you following this thread with bated breath.

I did check the resistors and the transistor in the VFO.
They were right.... well at least the transistor was the one supplied with the kit.
Apparantly the Q1-2N4124 was switched with a ZVN4424 in the parts supplied.

The right one is on the way from Elecraft so I think that will fix it.
We shall see.

Stan AE7UT

[Gordon LaPoint]

I also have a K1 that I'm building, with the same error code - no LO.  I'm interested in
any of the possible solutions!

Thanks!

Gordon - N1MGO

On 20 Aug 2012 at 13:34, Stan AE7UT wrote:

> For those of you following this thread with bated breath.
>
> I did check the resistors and the transistor in the VFO.
> They were right.... well at least the transistor was the one supplied with
> the kit.
> Apparantly the Q1-2N4124 was switched with a ZVN4424 in the parts supplied.
>
> The right one is on the way from Elecraft so I think that will fix it.
> We shall see.
>
> Stan AE7UT
>
>
>
>
>
> --
> View this message in context:
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> 50.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Stan AE7UT]

Gordon look closely at Q1 on the Front Panel Board.
The transistor supplied in my kit was the wrong one... but very close.
They have the same casing and the numbers are very close.
The one I got was   ZVN 4424.  It should be the 2N 4124.
I thought it was just a "replacement" for the 4124.  It's not.
Maybe you got the same switch?

Stan AE7UT

[Don Wilhelm-4]

Check your transistor numbers.  K1 Q1 is a 2N7000 FET and not a 2N4124.  
The ZVN4424 goes in the T-R switch at location Q4.

The VFO transistor (well OK an FET) is a J309 at Q8.

Possible solutions for a "no VFO" problem are diode D17 installed
backwards, and also D3 and D4 varactors.  Check the Parts Placement
diagrams at the back of the manual if you cannot discern the banded end
on the board silkscreen.

Inspect all components shown in the schematic sheet 1 marked "VFO" for
proper values and reflow the soldering on those components using a hot
soldering iron (750 degF).
Examine your soldering with a critical eye - if your soldered leads look
like balls, then the solder pad did not receive adequate heat. A good
solder connection should look like a "mountain" with a nice concave
fillet - anything convex is suspect.  Also it is said that the
connection should not look "like a volcano" which indicates either an
improperly stripped and tinned toroid lead or a normal lead that did not
receive enough heat.

Always watch for the solder to flow out both onto the component lead,
and also onto the solder pad.  I have repaired many Elecraft
transceivers just by re-flowing the soldering.

73,
Don W3FPR

On 8/21/2012 5:28 PM, Gordon LaPoint wrote:

> I also have a K1 that I'm building, with the same error code - no LO.  I'm interested in
> any of the possible solutions!
>
> Thanks!
>
> Gordon - N1MGO
>
> On 20 Aug 2012 at 13:34, Stan AE7UT wrote:
>
>> For those of you following this thread with bated breath.
>>
>> I did check the resistors and the transistor in the VFO.
>> They were right.... well at least the transistor was the one supplied with
>> the kit.
>> Apparantly the Q1-2N4124 was switched with a ZVN4424 in the parts supplied.
>>
>> The right one is on the way from Elecraft so I think that will fix it.
>> We shall see.
>>
>> Stan AE7UT
>>
>>
>>
>>
>>
>> --
>> View this message in context:
>> http://elecraft.365791.n2.nabble.com/K1-building-problem-VFO-not-working-tp7561287p75613
>> 50.html
>> Sent from the Elecraft mailing list archive at Nabble.com.
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
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[Mike Morrow-3]

Don wrote:

> Check your transistor numbers.  K1 Q1 is a 2N7000 FET and not a 2N4124.  
> The ZVN4424 goes in the T-R switch at location Q4.

Stan was referring to Q1 on the front panel board, which is the frequency
counter amplifier, 2N4124.  This could cause the problem as described,
so I would hold off on a wholesale rework of the VFO circuitry until the
frequency counter sensing path is repaired.

The VFO itself may likely be operating properly, but just not being sensed
by the FP-MPU.  In that case, the VFO signal should be able to be heard in a
receiver covering about 2.9 to 3.1 MHz (for 170 kHz VFO span).  Lacking a
receiver, the filter board should be able to be peaked to where static
and signals are heard...one just won't know what the exact frequency is
until FP-Q1 is fixed.

73,
Mike / KK5F
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[Stan AE7UT]

Got the right transistor put it and all is working well.

Thanks for all the help!
You guys are great.

73
Stan AE7UT

[Gordon LaPoint]

For those interested in this problem, it turned out to be one of the cap's in the LO.  
C5, C11 and C12.  I changed all three and now the LO is working correctly.  Turns out it
was oscillating, just on the wrong frequency, 7.8Mhz, which I did not see until I lifted
R5 and Q9 to unload the LO.

Thanks for the help, especially from Don, W3FPR and Elecraft for shipping me new parts,
rapidly and at no cost!
Now on to finishing the kit!

Gordon - N1MGO

On 21 Aug 2012 at 17:28, Gordon LaPoint wrote:

> I also have a K1 that I'm building, with the same error code - no LO.  I'm interested in
> any of the possible solutions!
>
> Thanks!
>
> Gordon - N1MGO
>
> On 20 Aug 2012 at 13:34, Stan AE7UT wrote:
>
> > For those of you following this thread with bated breath.
> >
> > I did check the resistors and the transistor in the VFO.
> > They were right.... well at least the transistor was the one supplied with
> > the kit.
> > Apparantly the Q1-2N4124 was switched with a ZVN4424 in the parts supplied.
> >
> > The right one is on the way from Elecraft so I think that will fix it.
> > We shall see.
> >
> > Stan AE7UT
> >
> >
> >
> >
> >
> > --
> > View this message in context:
> >
> http://elecraft.365791.n2.nabble.com/K1-building-problem-VFO-not-working-tp7561287p75613
> > 50.html
> > Sent from the Elecraft mailing list archive at Nabble.com.
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

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