K2 PLL Range

[John Heaviside]

I am slowly building a K2 and have run into a problem:

PLL Reference Oscillator Range Test (page 57 of manual).
The 4 MHz osc has been calibrated to an external counter with known accurate reference.
In CAL FCTR the counter reads 12099.15 MHZ
Tap BAND+ there is no change to this reading.
Tap BAND- the reading briefly changes to 12079.?? (too fleeting to read decimals) and instantly reverts to 12099.15.

Are there 2 problems here?  a) the reading at BAND- should presumably remain steady.  b) The range, if 12079 is correct is way outside the specified 9.5-15kHz.

Proceeding beyond this point everything seems to work but the VCO voltage at 7.000MHz is only 1.08V (page 58). L30 must be adjusted to 7.5V at 4.000MHz to get the 7.000 MHz reading up to 1.5V.  This seems too close to the limits for comfort.

Testing fails at page 60 VFO Linearisation.  Definitely on 40metres but CAL PLL produces INFO 232.

Have checked the components and all seem OK.  L31 is 12 microH and thermistor board installed.

Any ideas?

Thanks in advance.

John G3NYX.
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[Don Wilhelm-3]

John,

It is likely that you will find your problem on the thermistor board.  Look
VERY carefully at the soldering, then look again, and then once more.  It
appears that the PLL is trying to work, but there is a bad connection
somewhere - most likely the thermistor board.  There could be a bad solder
connection anywhere in the PLL area too (R19 and RP2 for example) - double
and triple check them all.

Don't draw any other conclusions (including the range) until you have the
PLL readings settled down.

73,
Don W3FPR

----- Original Message -----

I am slowly building a K2 and have run into a problem:

PLL Reference Oscillator Range Test (page 57 of manual).
The 4 MHz osc has been calibrated to an external counter with known accurate
reference.
In CAL FCTR the counter reads 12099.15 MHZ
Tap BAND+ there is no change to this reading.
Tap BAND- the reading briefly changes to 12079.?? (too fleeting to read
decimals) and instantly reverts to 12099.15.

Are there 2 problems here?  a) the reading at BAND- should presumably remain
steady.  b) The range, if 12079 is correct is way outside the specified
9.5-15kHz.



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[Tom Arntzen]

And!! One source to the info 232 message during cal pll can be that your
testprobe is in TP2 instead of TP1.
I have often forgotten that point and get the info 232 message.
Other than that , check what Don said.
Tom LA1PHA

----- Original Message -----
From: "John Heaviside" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, November 10, 2004 8:40 PM
Subject: [Elecraft] K2 PLL Range


I am slowly building a K2 and have run into a problem:

PLL Reference Oscillator Range Test (page 57 of manual).
The 4 MHz osc has been calibrated to an external counter with known accurate
reference.
In CAL FCTR the counter reads 12099.15 MHZ
Tap BAND+ there is no change to this reading.
Tap BAND- the reading briefly changes to 12079.?? (too fleeting to read
decimals) and instantly reverts to 12099.15.

Are there 2 problems here?  a) the reading at BAND- should presumably remain
steady.  b) The range, if 12079 is correct is way outside the specified
9.5-15kHz.

Proceeding beyond this point everything seems to work but the VCO voltage at
7.000MHz is only 1.08V (page 58). L30 must be adjusted to 7.5V at 4.000MHz
to get the 7.000 MHz reading up to 1.5V.  This seems too close to the limits
for comfort.

Testing fails at page 60 VFO Linearisation.  Definitely on 40metres but CAL
PLL produces INFO 232.

Have checked the components and all seem OK.  L31 is 12 microH and
thermistor board installed.

Any ideas?

Thanks in advance.

John G3NYX.
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[Jessie Oberreuter]

      I had this problem when I was first building my K2 a few years back.
I was scratching my head for hours.  Finally put a logic analyzer on the
bus and found the problem: I believe it was the RIT control -- every time
a change was detected, the MPU would snap the VFO back.  For some reason,
mine was a little scratchy or was otherwise wandering around by +/- 1 and
it was enough.  I fiddled with it a bit and everything was fine.  I meant
to make sure I didn't miss a step in the manual saying to rail the
control, and/or post this experience to the reflector, but I don't think I
ever did.


On Wed, 10 Nov 2004, John Heaviside wrote:

> PLL Reference Oscillator Range Test (page 57 of manual).
> The 4 MHz osc has been calibrated to an external counter with known accurate reference.
> In CAL FCTR the counter reads 12099.15 MHZ
> Tap BAND+ there is no change to this reading.
> Tap BAND- the reading briefly changes to 12079.?? (too fleeting to read decimals) and instantly reverts to 12099.15.
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[John Heaviside]

Yes!  Thanks Jessie.
A small movement of the RIT pot and the PLL Osc range BAND+/BAND- worked
with stable reading except when RIT was full +ve.
I am still a little concerned as the + reading is 12099.1 and the - reading
actually 12078.4 so the range is over 20kHz and well outside the specified
9.5 to 15.
However, the VFO linearisation then worked OK and after that the PLL osc
range test also worked with the RIT fully +ve!  So I don't think it was a
scratchy pot.  Something in the software?

Will continue with construction!

Regards,  John. G3NYX


----- Original Message -----
From: "Jessie Oberreuter" <[hidden email]>
To: "John Heaviside" <[hidden email]>
Sent: Thursday, November 11, 2004 10:36 PM
Subject: Re: [Elecraft] K2 PLL Range


>
> Did this solve your problem?  Mayhap it was a different pot?
>
>
> On Wed, 10 Nov 2004, Jessie Oberreuter wrote:
>
> >
> >     I had this problem when I was first building my K2 a few years back.
I
> > was scratching my head for hours.  Finally put a logic analyzer on the
bus
> > and found the problem: I believe it was the RIT control -- every time a
> > change was detected, the MPU would snap the VFO back.  For some reason,
mine
> > was a little scratchy or was otherwise wandering around by +/- 1 and it
was
> > enough.  I fiddled with it a bit and everything was fine.  I meant to
make
> > sure I didn't miss a step in the manual saying to rail the control,
and/or

> > post this experience to the reflector, but I don't think I ever did.
> >
> >
> > On Wed, 10 Nov 2004, John Heaviside wrote:
> >
> >> PLL Reference Oscillator Range Test (page 57 of manual).
> >> The 4 MHz osc has been calibrated to an external counter with known
> >> accurate reference.
> >> In CAL FCTR the counter reads 12099.15 MHZ
> >> Tap BAND+ there is no change to this reading.
> >> Tap BAND- the reading briefly changes to 12079.?? (too fleeting to read
> >> decimals) and instantly reverts to 12099.15.
> >
>
>

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