I got my brand new 100G ohm resistor (it's sealed in an evacuated glass envelope) and it measures only 50G Ohm!!!
What could be the problem?
If I disconnect the coax with the alligator clips on the end, it measures (open circuit) 100G ohm.
If I disconnect the coax, it measures something in excess of 10T ohm (the max reading is 10T ohm).
Interestingly, the PL-259 to BNC adapter, if removed makes no noticeable difference to the reading. For a very cheap adapter (it cost me 5c) that's not too bad. From the look of it, it has the same teflon insulation as the built-in PL-259 socket. (Dick Smith Electronics sold me about a dozen of them for 5c each as they were closing down. Looks like they were reasonable quality!)
In the 10^13 ohm range, it takes several minutes for the needle to move across the dial and then to pin against the end stop. I could probably time the difference with and without the PL-259 adapter (what a good idea).
It takes 3 min 33 sec to reach full scale with the PL259 adapter, and 2 min 40 sec without it. Clearly a measurable difference, but I'm not going to hazard a guess at the possible resistance.
Should I shell out for a 1T ohm resistor? What about a 10T ohm resistor?
I'm happy that my 100G resistor is pretty close to 100G though
What could be the problem?
If I disconnect the coax with the alligator clips on the end, it measures (open circuit) 100G ohm.
If I disconnect the coax, it measures something in excess of 10T ohm (the max reading is 10T ohm).
Interestingly, the PL-259 to BNC adapter, if removed makes no noticeable difference to the reading. For a very cheap adapter (it cost me 5c) that's not too bad. From the look of it, it has the same teflon insulation as the built-in PL-259 socket. (Dick Smith Electronics sold me about a dozen of them for 5c each as they were closing down. Looks like they were reasonable quality!)
In the 10^13 ohm range, it takes several minutes for the needle to move across the dial and then to pin against the end stop. I could probably time the difference with and without the PL-259 adapter (what a good idea).
It takes 3 min 33 sec to reach full scale with the PL259 adapter, and 2 min 40 sec without it. Clearly a measurable difference, but I'm not going to hazard a guess at the possible resistance.
Should I shell out for a 1T ohm resistor? What about a 10T ohm resistor?
I'm happy that my 100G resistor is pretty close to 100G though