Hazards of Accumulating Electric Charge in 1.85mm Cable Assembly

In most RF test scenarios, the problem of charge accumulation will not be involved, but a very typical scenario is the production test of 1.85mm coaxial cable. As mentioned earlier, the dielectric withstand voltage test is performed during the production of the 1.85mm cable assembly, which results in a large amount of charge on the inner conductor. In order to ensure the performance and quality of the 1.85mm cable assembly, in addition to the above-mentioned dielectric withstand voltage test, it is usually necessary to test the characteristic impedance and impedance discontinuity to detect whether there is a breakpoint in the 1.85mm cable assembly. It is also essential to test parameters such as insertion loss and port VSWR of the 1.85mm cable assembly.

                                                      
The above electrical parameter tests require the use of TDR and VNA  [VNA Test Cable]. After the dielectric withstand voltage test is completed, you must be careful to test these electrical parameters directly. If you do not release the accumulated charge on the inner conductor, it is easy to burn out the test equipment. I often hear 1.85mm cable assembly manufacturers complaining about "why the TDR and VNA are so fragile", why the TDR module and the VNA were burned out when testing the cable.

                                                     
In fact, all the meters are designed with anti-static level, especially VNA [VNA Test Cable]. Under the circumstance that the operator takes proper anti-static measures, the reason why the instrument will burn out is mostly caused by the charge accumulated in the inner conductor. When the 1.85mm cable assembly with charge is connected to the test equipment, the charge will flow to the reference ground of the entire system through the analog channel of the test equipment. If the amount of charge is large enough, it will directly burn the analog front-end components. Another point to note is that whether it is electrostatic discharge or the above-mentioned accumulated charge discharge, it has a cumulative effect on the damage to the device channel - even if one discharge does not burn out the analog channel, but the number of discharges is too many, the analog channel will slowly break down Lost. [1.85mm Cable Assembly]