Ferrites for low frequency microwave hybrids and couplers

[Higgler]

Hello,
Are there any readers that have designed Ferrite hybrids and or couplers. I've researched alot of companies that make them and have ordered a dozen items, but I'm curious about detailed operation/failure mechanisms for both electrical and mechanical at hot and cold.

Questions;
1) How do you protect them against vibration failure, ferrites are brittle. I assume some sort of potting can be used to stabilize them, or do you need to partly cushion them against shock? Can I spray a potting compound on a purchased part. After opening the part, I see ferrite beads on a wire and I'm not sure if they used any potting to keep the part in place. Any experience in this area?

2) Performance at hot degrades when the ferrite temp hit's the Curie point I've read and they lose their magnetic properties. How about at cold, do ferrite properties change slowly?

3) Ferrite source if we were to design our own? I'd like to find a source to read, then a human to talk to.

4) If you have designed some previously, could you provide a design example for me to look at?

Thanks,
kch (ferrite rookie).

 

[zappedagain]

I like Amidon for ferrite cores. I haven't done wide temperature designs though so I'm not much help there.

I've done air-core inductors in the past and melted wax onto them to maintain their shape. That was good enough to survive a drop test in consumer electronics, but may not help your high temperature operation. Just make sure your potting compound doesn't significantly change the inductance; should be no problem with ferrite but be sure to double check.