[Elecraft] xg-1 question

Tue Feb 3 08:35:00 2004

Hi John

When the instructions say to measure the resistance to ground then the =
negative or black probe will connect to one of the ground loops or some =
other ground point. The positive or red probe connects to the component =
or other point called out in the instructions. The black probe does not =
move from ground.=20

If the instructions ask you to measure the resistance across a component =
or two points then the black lead will connect to one of the points and =
the red lead will connect to the other. For example if you are asked to =
measure across a resistor then the black lead will connect to one end of =
the resistor and the red will connect to the other.=20

Because you are measuring in circuit sometimes semiconductor components =
like transistors, diodes or the internal circuits in IC's will change =
the reading depending on the polarity of the meter. If the reading looks =
funny try reversing the red and black probe positions. If the reading is =
closer to the call out in the manual you are most likely still OK. =
Sometimes a large capacitor is in the circuit and you will need to wait =
a few seconds for it to charge before the reading is stable. Changing =
ranges on the meter will also make a difference sometimes because some =
resistance ranges have enough voltage to turn on any semiconductors in =
the circuit while other ranges do not.=20

Unfortunately in circuit resistances measurement is not an exact =
science. There are too many variables in the meter circuits and how they =
interact with the semiconductors in the circuit under test. We are only =
looking for ball park readings. If there is a gross error then you need =
to find the problem. If the reading is close then you are probably OK. =
However the voltage measurements should be very close to the manual call =
outs usually within 5% or less.=20

Don Brown
KD5NDB

  ----- Original Message -----=20
  From: John Cooper<mailto:[email protected]>=20
  To: [email protected]<mailto:[email protected]>=20
  Sent: Monday, February 02, 2004 4:46 PM
  Subject: [Elecraft] xg-1 question

  Im to the part where you measure resistance to ground at each of the =
points listed.  the junctions of the resistor and caps so far installed.

  could someone give me an example of the junction of R7 and R8.  Where =
exactly do the probes go?  Across both I get the 50OHM which is good.  =
Does it matter, I put one probe on the right side of R7 and the other on =
the bottom of R8.  It was the same reading when I moved it to the top of =
R8.  Usually you put one probe on the ground loop in the k2 and to the =
component.  Im probably just thinking too much into this. =20

  WT5Y  I promise you guys Im absorbing as much as I can as fast as I =
can.

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