fatllama
A high-pass filter; getting desperate!
One of our group's ion traps hasn't trapped ions at all yet. The last thing on my troubleshooting checklist is eliminating any low-frequency noise out of our high power radio frequency amplifier that could tickle and heat ions through secular motion.
Hence, this high-pass filter. It's an aggressive 7-pole Chebyshev filter, designed with the tools that come with the venerable ARRL handbook.
Two rf circuit tricks I employed: rotation of each successive inductor, and placement of grounded copper-board 'wedges' between stages to reduce cross-coupling.
The results were great. I wanted to pass 5.6 MHz and above with very little loss but murder everything below 2 MHz. The measured loss at 5.6 MHz is 1 dB, or about 20%, while the attenuation at 1 MHz is 76 dB, or < 0.00001 %.
Update: Liverpool now traps, after months of frustration!! But the filter wasn't the key because it now traps without it. The mystery continues.
A high-pass filter; getting desperate!
One of our group's ion traps hasn't trapped ions at all yet. The last thing on my troubleshooting checklist is eliminating any low-frequency noise out of our high power radio frequency amplifier that could tickle and heat ions through secular motion.
Hence, this high-pass filter. It's an aggressive 7-pole Chebyshev filter, designed with the tools that come with the venerable ARRL handbook.
Two rf circuit tricks I employed: rotation of each successive inductor, and placement of grounded copper-board 'wedges' between stages to reduce cross-coupling.
The results were great. I wanted to pass 5.6 MHz and above with very little loss but murder everything below 2 MHz. The measured loss at 5.6 MHz is 1 dB, or about 20%, while the attenuation at 1 MHz is 76 dB, or < 0.00001 %.
Update: Liverpool now traps, after months of frustration!! But the filter wasn't the key because it now traps without it. The mystery continues.