K-2 Control Board Resistance Checks Fail

[Brian Wruble]

Hi all:

I am assembling K-2 S/N 4397.  I have just completed the Control Board.  Two
of the resistance checks fail.  The resistance between the collectors of
both Q1 and Q2 to ground measure 454 K each.  They are supposed to show
resistance >1meg to ground.  I have checked resistor network RP1.  It is
installed correctly.  On RP1, the resistance between 1&2, 3&4, 5&6, 7&8 and
9&10 are all 3.9K.  Resistance checks between 2&3, 4&5, 6&7 are all under 1
ohm.  Resistance between 8&9 is about 1.5k.  That strikes me as an anomoly,
but I'm not sure.

Can anyone tell me whether this looks good, or suggest where the problem
might be?

Tnx.  73 de Brian W3BW


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[Don Brown-4]

Hi

Try reversing the ohmmeter leads or changing ranges and see if the readings look better. If not I wouldn't worry about it. You are mainly looking for gross errors like very low readings or shorts. Some DVM ohms ranges will turn on semiconductors in the circuits and that will give the effect of a lower than expected reading. Changing ranges or reversing the leads may keep the semis from conducting.

Don Brown
KD5NDB
  ----- Original Message -----
  From: Brian Wruble<mailto:[hidden email]>
  To: [hidden email]<mailto:[hidden email]>
  Cc: Elecraft Discussion List<mailto:[hidden email]>
  Sent: Sunday, August 08, 2004 1:07 PM
  Subject: [Elecraft] K-2 Control Board Resistance Checks Fail


  Hi all:

  I am assembling K-2 S/N 4397.  I have just completed the Control Board.  Two
  of the resistance checks fail.  The resistance between the collectors of
  both Q1 and Q2 to ground measure 454 K each.  They are supposed to show
  resistance >1meg to ground.  I have checked resistor network RP1.  It is
  installed correctly.  On RP1, the resistance between 1&2, 3&4, 5&6, 7&8 and
  9&10 are all 3.9K.  Resistance checks between 2&3, 4&5, 6&7 are all under 1
  ohm.  Resistance between 8&9 is about 1.5k.  That strikes me as an anomoly,
  but I'm not sure.

  Can anyone tell me whether this looks good, or suggest where the problem
  might be?

  Tnx.  73 de Brian W3BW


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[Brian Wruble]

Thanks for the tip.  That worked.  One reads infinite, and the other 1.1meg
when I reverse the leads.
 
Nothing beats this reflector for nearly instant (and accurate) help and
info.
 
73, Brian

  _____  

From: Don Brown [mailto:[hidden email]]
Sent: Sunday, August 08, 2004 1:38 PM
To: Brian Wruble
Cc: Elecraft Discussion List
Subject: Re: [Elecraft] K-2 Control Board Resistance Checks Fail


Hi
 
Try reversing the ohmmeter leads or changing ranges and see if the readings
look better. If not I wouldn't worry about it. You are mainly looking for
gross errors like very low readings or shorts. Some DVM ohms ranges will
turn on semiconductors in the circuits and that will give the effect of a
lower than expected reading. Changing ranges or reversing the leads may keep
the semis from conducting.
 
Don Brown
KD5NDB

----- Original Message -----
From: Brian  <mailto:[hidden email]> Wruble
To: [hidden email]
Cc: Elecraft Discussion List <mailto:[hidden email]>  
Sent: Sunday, August 08, 2004 1:07 PM
Subject: [Elecraft] K-2 Control Board Resistance Checks Fail

Hi all:

I am assembling K-2 S/N 4397.  I have just completed the Control Board.  Two
of the resistance checks fail.  The resistance between the collectors of
both Q1 and Q2 to ground measure 454 K each.  They are supposed to show
resistance >1meg to ground.  I have checked resistor network RP1.  It is
installed correctly.  On RP1, the resistance between 1&2, 3&4, 5&6, 7&8 and
9&10 are all 3.9K.  Resistance checks between 2&3, 4&5, 6&7 are all under 1
ohm.  Resistance between 8&9 is about 1.5k.  That strikes me as an anomoly,
but I'm not sure.

Can anyone tell me whether this looks good, or suggest where the problem
might be?

Tnx.  73 de Brian W3BW


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Post to: [hidden email]
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http://mailman.qth.net/mailman/listinfo/elecraft   
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[Robert McGwier]

Another clue that this is happening  (charging capacitive loads, etc.) is
that
the reading will be sliding, drifting while you are watching it.  If you see
this,
reverse the leads.

Bob
N4HY


-----Original Message-----
From: elecraft-bounces+rwmcgwier=[hidden email]
[mailto:elecraft-bounces+rwmcgwier=[hidden email]]On Behalf
Of Brian Wruble
Sent: Sunday, August 08, 2004 6:42 PM
To: [hidden email]
Cc: 'Elecraft Discussion List'
Subject: RE: [Elecraft] K-2 Control Board Resistance Checks Fail


Thanks for the tip.  That worked.  One reads infinite, and the other 1.1meg
when I reverse the leads.

Nothing beats this reflector for nearly instant (and accurate) help and
info.

73, Brian


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