Hello,
I have a question about how to select an RF choke for isolating oscillator frequencies from a DC power source. The circuit I am building contains 4 oscillators, one each at 150 kHz, 500 kHz, 1.4 MHz, and 30 MHz respectively. The goal is to sum these frequencies and capacitively couple them onto a household power mains. Ultimately this device will be used to test a CISPR 14 discontinuous interference analyzer. I have a working prototype up to the summing part. The problem I am having is controlling the amplitudes of the individual frequencies. This is due mostly to coupling of the frequencies on the 5 Vdc and GND lines that power the circuit, particularly the higher frequencies. I would like to isolate the 5V and GND lines from the oscillators and ICs in the circuit with RF chokes. I'm not very concerned with the 150 or 500 kHz oscillators although I will still isolate them. I would like to use the same value choke for all connections. I'm thinking something around 100 mH will work. I have looked at a few data sheets for chokes, but I'm confused about how to weigh things like self resonant frequencies and DC resistance along with the inductance. Any suggestions?
I have a question about how to select an RF choke for isolating oscillator frequencies from a DC power source. The circuit I am building contains 4 oscillators, one each at 150 kHz, 500 kHz, 1.4 MHz, and 30 MHz respectively. The goal is to sum these frequencies and capacitively couple them onto a household power mains. Ultimately this device will be used to test a CISPR 14 discontinuous interference analyzer. I have a working prototype up to the summing part. The problem I am having is controlling the amplitudes of the individual frequencies. This is due mostly to coupling of the frequencies on the 5 Vdc and GND lines that power the circuit, particularly the higher frequencies. I would like to isolate the 5V and GND lines from the oscillators and ICs in the circuit with RF chokes. I'm not very concerned with the 150 or 500 kHz oscillators although I will still isolate them. I would like to use the same value choke for all connections. I'm thinking something around 100 mH will work. I have looked at a few data sheets for chokes, but I'm confused about how to weigh things like self resonant frequencies and DC resistance along with the inductance. Any suggestions?