K2 build - VCO Test / Alignment issue

[John Hoaglun-2]

I have entered the Alignment and Test Part II portion of my K2 build.
 
The "PLL reference oscillator range test" seems to check out fine. But when
I run the "VCO test" (which is 80m @ 4000.10khz @ TP1 = 8-10MHz) I am not
seeing much of anything on the frequency counter. (I see readings on TP2 and
TP3 but not TP1.)
 
Any suggestions from others that have seen issues at this step in the check
out process?
 
Thanks, JH
 
-----------------------------
John Hoaglun
NG0R - EN25
http://www.hoaglun.com
 
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[Kurt Cramer-2]

John,

I would check all componets in the area of U3 backward to U6B. Make sure
everything is in the proper place and that they are all soldered. Sorry, it
will take some time, but that's the only way.

Kurt
----- Original Message -----
From: "John Hoaglun" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, June 10, 2008 6:36 AM
Subject: [Elecraft] K2 build - VCO Test / Alignment issue

>I have entered the Alignment and Test Part II portion of my K2 build.
>
> The "PLL reference oscillator range test" seems to check out fine. But
> when
> I run the "VCO test" (which is 80m @ 4000.10khz @ TP1 = 8-10MHz) I am not
> seeing much of anything on the frequency counter. (I see readings on TP2
> and
> TP3 but not TP1.)
>
> Any suggestions from others that have seen issues at this step in the
> check
> out process?
>
> Thanks, JH
>
> -----------------------------
> John Hoaglun
> NG0R - EN25
> http://www.hoaglun.com
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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> Elecraft web page: http://www.elecraft.com
>

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[Don Wilhelm-4]

JH,

It may be time to take a break and build the RF probe from the parts
included with your K2.
What I am suggesting is that knowing the RF voltage levels at TP1 and
other places in the VFO circuit would be informative and help us to
assist you in your troubleshooting quest.

At this point, about the only thing I can suggest is that you check the
soldering, and then re-check the soldering, and when that is done -
check the soldering.  Soldering is the most frequent cause of failure.  
Oh, yes, toroid lead tinning is the second most frequent problem, so
check the leads of T5 carefully and re-tin if necessary.  Check all
active devices (diodes included) for correct orientation - the parts
placement diagrams in the back of the manual are handy for checking
orientation.

Look at the schematic for the RF Board sheet 1 to identify the
components that are of interest for your problem.   Everything on the
upper portion of that sheet to the right of U4 is on the suspect list.

73,
Don W3FPR

John Hoaglun wrote:

> I have entered the Alignment and Test Part II portion of my K2 build.
>  
> The "PLL reference oscillator range test" seems to check out fine. But when
> I run the "VCO test" (which is 80m @ 4000.10khz @ TP1 = 8-10MHz) I am not
> seeing much of anything on the frequency counter. (I see readings on TP2 and
> TP3 but not TP1.)
>  
> Any suggestions from others that have seen issues at this step in the check
> out process?
>  
> Thanks, JH
>  
> -----------------------------
> John Hoaglun
> NG0R - EN25
> http://www.hoaglun.com
>  
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft   
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
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