Frequently Asked Questions
Hardware
Q: Should I add any extra protection for the scope I'll connect to the output?
A: You may do so. At CERN we have used the 11930A Power Limiter, DC to 6 GHz, APC-7.
Q: What's the relay type used in this design?
A: The relays used in the design are TYCO AXICOM HF3 53 or 1462051-2. The specifications gives a Mechanical Endurance of 1E7 (10 million) operations. The Electrical endurance is not given.
The definition of Mechanical Endurance by Tyco:
Number of cycles without contact load during which the relay remains within the specified characteristics.
NOTE that the failure criteria for mechanical endurance are not the same as for electrical endurance, therefore the value for mechanical endurance has no relation and cannot be directly compared to electrical endurance for very low loads!
Q: Is 10 million switching cycles a lot?
A: We have some special application for CERN's accelerators, where the relays would be used in five years time as explained in the case below.
As a worst case estimate I assume runs from 15/02 to 15/12 in both PSB and PS which corresponds to 26.2 million seconds. In the PSB all cycles are 1.2 s long, hence by constantly toggling between two cycles one could reach 21.8 million switchings per year. In the PS, cycles are 1.2 s or 2.4 s long, with few cycles even 3.6 s. Assuming toggling at an average cycle rate of 1.5 bp = 1.8 s, one would reach 14.5 million switchings per year. I am aware that this is beyond the specified mechanical lifetime of the relays (10 million), however one would need to apply a reduction factor to these worst case estimate. You will learn with time, but the lifetime of the attenuators, when used in full PPM, will probably be ~5 years.
3 June 2022