VK3BHR LC meter inductance measurement problem #homebrew


ashok.das81@...
 

Hi all,

I am making the LC meter V2 designed by VK3BHR Phil RIce. I have seen many have done this and it works fine, but in my case it is not measuring inductance properly. For example a 90uH coil shows 52uH, 3.3uH shows 0.3uH. The measurement is completely wrong. Capacitance measurement is looking OK. Calibration was done using a 1% 100pF NP0 capacitor. I checked F1 and F2.

F1=00042879 (little lower than recommended value of 00050000 +- 5%)
F2=00032223 (within 71% of F1)

I have used all new components and L is a 100uH +/-20% toroid. C and Ccal are 1000pF NP0 +/-5%. I am using the PCB designed by VK3BHR. The relay is driven by a BC548B transistor as I cannot find a low current relay and I have checked the RELAY its clicking and contact resistance is less than 1 ohm. I am thinking that the +/-20% tolerance for the 100uH toroid is too high. What else could be wrong ? I will provide any other info that is useful for troubleshooting.

Can anyone help me to find out the problem.

Thanks
Ashok

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