Does Bias 1 ohm resistor tolerance matter?

[psychepool]

For easy bias measurement, I always connect 1 ohm to the cathode of the Fixed Bias amp's power tube.

I am using a resistor with a 1% tolerance purchased from an online shop I frequently use. When I purchase it and actually measure it, it usually measures between 0.8 and 1.2 ohms.

However, I needed a 1-ohm resistor, so I took out the resistors I bought at that store a long time ago from the drawer and measured them, and they measured about 2.5 to 3.3 ohms.
The color band is clearly 1 ohm.

There may be an assumption that there may be a problem with the multimeter, but if this much error occurs in the measured value, will a serious error occur when measuring bias through this resistor? In theory, there would be a difference of more than 2-3 times, but is this actually the case?

[dorrisant]

The closer you get to 1 ohm, the closer you can directly convert the mV reading to mA. So if your resistor reads 2-3 ohms then your measurements would be way off.

[chaccmgr]

most multimeters have problems measuring small resistances exactly...
If you don't have access to a trusted one, maybe comparing measurements from different multimeters give you a feeling of how far your multimeter(s) is/are off
I know, this is not a solution but shows if your eqipment is the problem.

you can also apply a known voltage which is higher than a battery and measure the voltage drop and calculate the resistance using Ohm's law

[pdf64]

Shorting the meter probes together prior to measuring any resistance is a basic sanity check.

[martin manning]

If you have 1Ω 1% resistors from a reliable source, just accept that they are within 1% of 1Ω. You need a 4-wire measurement system to measure that resistance within tolerance.

[GAStan]

As already said, tighter tolerance makes the math easier. I'll add that a closely matched set of resistors, regardless of tolerance, means you only need to do the math once. When I buy from Mouser or Digi-Key a quantity of 10 is generally not much more than 4 so I get 10. Then I test them all and pick the best matched set.

Shorting the probes together will let you know how much error you have. Even the expensive Fluke meters we use at work don't have a perfect 0.0 when shorted, typically 0.1 to 0.3. I've always understood it to be the resistance of the test leads themselves. It also lets me know how much error to account for when reading small resistances.

How are you connecting the test leads to the resistor leads? Simply holding them in your hands can give erroneous readings. Especially on older components due to a possible oxide layer on the leads. I use alligator clips which will cut through any layers and make good metal to metal contact.

Repeatability is also important and a good way to check yourself. If you measure it three times and get three different readings something is wrong, either with the meter/leads, component under test, or your testing methods. On the other hand if all three times you get the same (or reasonably close) readings then it's likely good.