Alignement and Test part II - VCO Test not reading 8 to 10 MHZ range.

[VA2EK]

On K2 serial 7168, I measure in the 12,000 MHz range.  If this can be of useful info, in the VFO Alignement Test, there is no voltage at R30 and the R30 value doesn't change upon L30 position.

Thanks,

Mario -VA2EK.

[Don Wilhelm-4]

Mario,

I assume "no voltage" is equal to zero volts, which is a perfectly valid
voltage measurement.  I know it is a subtle point, but such clarity is
important for successful troubleshooting.

A zero volts indication at the left end of R30 is an indication that the
VCO/PLL circuits are trying to create more capacity in the varactors
because the frequency is too high.

The first thing to do is check the number of red turns on T5 - it must
be 16.
Then check the value of C72 - it must be 270 pF (marked 271).
Check the soldering of C72, T5, and relays K13, K14 and K15. Re-flow the
solder with a hot iron (750 degF).

Additional checks -- do you have 4 volts at U6 pin 5?  If not, you have
a problem with the Thermistor Board (likely a solder bridge). You can
reach the solder side of the Thermistor board by removing the Control
Board and Front Panel.

If those steps do not fix it, ask again and we can offer more
measurements and suggestions.

BTW: If you are posting from Nabble, include some of this post in your
reply text so those of us who are receiving the direct reflector posts
have some reference for what has gone on before.  It seems Nabble strips
out the prior post history assuming that everyone uses the Nabble
"forum" - that is a bad assumption.  Copy a part of the previous post in
your reply so we have a reference.

73,
Don W3FPR


On 1/11/2014 3:13 PM, VA2EK wrote:
> On K2 serial 7168, I measure in the 12,000 MHz range.  If this can be of
> useful info, in the VFO Alignement Test, there is no voltage at R30 and the
> R30 value doesn't change upon L30 position.
>
> Thanks,
>
> Mario -VA2EK.
>

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[VA2EK]

Don,

Once again you have pin pointed me to the right direction.  C72 was the issue, I had put in a 27uF instead of a 270uF capacitor.  Changed over the capacitor and everything became normal.  Don't know if we can attribute this to being a rookie in building kits, in any case I will make changes to my double-triple check procedure while building.

Went through all the Part II alignment and EVERYTHING is within specs.

I can even hear CW and phone on 40M.  What a great feeling!  

Even with its challenges I'm enjoying my K2 building experience!

Thank you for your prompt assistance Don, it is very much appreciated, especially over the weekend.

Best regards, hope to someday shake your hand and thank you personally.

73's

Mario - VA2EK.


---------------------------------

Mario,

I assume "no voltage" is equal to zero volts, which is a perfectly valid
voltage measurement.  I know it is a subtle point, but such clarity is
important for successful troubleshooting.

A zero volts indication at the left end of R30 is an indication that the
VCO/PLL circuits are trying to create more capacity in the varactors
because the frequency is too high.

The first thing to do is check the number of red turns on T5 - it must
be 16.
Then check the value of C72 - it must be 270 pF (marked 271).
Check the soldering of C72, T5, and relays K13, K14 and K15. Re-flow the
solder with a hot iron (750 degF).

Additional checks -- do you have 4 volts at U6 pin 5?  If not, you have
a problem with the Thermistor Board (likely a solder bridge). You can
reach the solder side of the Thermistor board by removing the Control
Board and Front Panel.

If those steps do not fix it, ask again and we can offer more
measurements and suggestions.

BTW: If you are posting from Nabble, include some of this post in your
reply text so those of us who are receiving the direct reflector posts
have some reference for what has gone on before.  It seems Nabble strips
out the prior post history assuming that everyone uses the Nabble
"forum" - that is a bad assumption.  Copy a part of the previous post in
your reply so we have a reference.

73,
Don W3FPR


On 1/11/2014 3:13 PM, VA2EK wrote:
> On K2 serial 7168, I measure in the 12,000 MHz range.  If this can be of
> useful info, in the VFO Alignement Test, there is no voltage at R30 and the
> R30 value doesn't change upon L30 position.
>
> Thanks,
>
> Mario -VA2EK.
>

______________________________________________________________
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