help on alignment and test, part II

[Lloyd Lachow]

 OK, I got to p.60. Plugged in the freq. probe, got it
to TP3, did the CAL thing, and got 0000.00. Tried to
measure with my DMM's freq counter with that still
connected...and while doing this, the K2 read about
10.96 something, changing rapidly. Disconnected the
DMM from TP#, the K2 read 00000.00 again. The DMM,
meanwhile, read 12.01 at TP3.

  I tried the VCO test at TP1, got 0000.00. Went to
troubleshooting, using my RF probe, checked the
Reference Oscillator output, got 0.767 Vrms. VCO
output = 0.418 Vrms. VCO Buffer output = 0.677 Vrms.
All seemed good!

  TP2 showed something, didn't write it down, but it
was, like, 4912 or something...showed my
carefully-built probe was working, I suppose.


  Then I checked some voltages, and found some wacky
stuff. On U4, pin 5 was zero. pin 7 was 5V. pin 8
showed rapid variation. Others were ok.

  On U5, pin 1 was 5V, and pin 2 was zero V!!! others
were ok. Yow!

   on U1, pins 9 and 10 showed rapid variation, others
were ok. U2, U3, U6, U8, U11 and U12 were all ok.

  Q17 had a D of 1.637, others ok. Q18 had S of 1.615
and D of 7.92.

   That's all I had time to check...hopefully, it's
enough for someone to suggest what to look for.

  Thanks!

   LL/K3ESE


               
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[Don Wilhelm-3]

LLoyd,

How old is your K2 kit?  Take a look at the MPS5179s on the Control Board at
Q9 and Q10 - if they are blue (rather than black), they are the cause of
your problem.  Elecraft will supply replacements for you if they are the
blue-faced ones.  In the meantime, you can use 2N2222s in their place if you
want to get up and running quickly (borrow the 2 2N2222s from the later part
of the RF board aseembly).

Other than the above 2N5179 problem or an improperly constructed counter
probe, I can't think of any reason you should not see proper readings on the
CAL FCTR display.  Check the connection of your probe to the Control Board -
the shield should be closest to the left side panel - should you have it
backwards, it will behave as you have described.

73,
Don W3FPR

> -----Original Message-----
>
>  OK, I got to p.60. Plugged in the freq. probe, got it
> to TP3, did the CAL thing, and got 0000.00. Tried to
> measure with my DMM's freq counter with that still
> connected...and while doing this, the K2 read about
> 10.96 something, changing rapidly. Disconnected the
> DMM from TP#, the K2 read 00000.00 again. The DMM,
> meanwhile, read 12.01 at TP3.
>
>   I tried the VCO test at TP1, got 0000.00. Went to
> troubleshooting, using my RF probe, checked the
> Reference Oscillator output, got 0.767 Vrms. VCO
> output = 0.418 Vrms. VCO Buffer output = 0.677 Vrms.
> All seemed good!
>
>   TP2 showed something, didn't write it down, but it
> was, like, 4912 or something...showed my
> carefully-built probe was working, I suppose.
>
>
>   Then I checked some voltages, and found some wacky
> stuff. On U4, pin 5 was zero. pin 7 was 5V. pin 8
> showed rapid variation. Others were ok.
>
>   On U5, pin 1 was 5V, and pin 2 was zero V!!! others
> were ok. Yow!
>
>    on U1, pins 9 and 10 showed rapid variation, others
> were ok. U2, U3, U6, U8, U11 and U12 were all ok.
>
>   Q17 had a D of 1.637, others ok. Q18 had S of 1.615
> and D of 7.92.
>
>    That's all I had time to check...hopefully, it's
> enough for someone to suggest what to look for.
>
>   Thanks!
>
>    LL/K3ESE
>

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