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THE AM BULLETIN BOARD => Military Amateur Radio Section => Topic started by: n5ama on January 04, 2025, 10:22:46 AM



Title: MOV line input protection
Post by: n5ama on January 04, 2025, 10:22:46 AM
I’ve placed a MOV on each leg of the power line input of my HT-9 for inrush current protection. After about 30 seconds, the units get hot and the voltage drop remains a few volts below line. I was wondering if two of these in series would help share the temperature load on each devise or does each have the same voltage drop with the temperature remaining the same regardless of using one or two in series.

I’m not sure if they are needed but if I’m only loosing a few volts line input, I can’t see where they would hurt.

Tom N5AMA


Title: Re: MOV line input protection
Post by: W7TFO on January 04, 2025, 10:48:33 AM
Your not saying how they are connected raises a question.

Leg to ground or leg to leg?

Most damaging transients occur against ground,  Leg to leg occurrences are much less damaging and rare, usually induced by something local to your ops.

Why they are getting hot is not right.  Is your normal line voltage really high?

73DG


Title: Re: MOV line input protection
Post by: n5ama on January 04, 2025, 11:03:27 AM
Hi, thanks for the reply. They are connected leg to leg. I think I remember the component type 90L if that makes any difference. My line voltage varies from 121 to 124.

Tom


Title: Re: MOV line input protection
Post by: n5ama on January 05, 2025, 09:14:19 AM
Connected hot leg to ground and all seems well, no heat. Inrush current protection still running hot.
Thanks
Tom
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