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Re: [Amps] Relais for an antenna crossover switch

To: "Guido Tedeschi" <guidoted@gmail.com>
Subject: Re: [Amps] Relais for an antenna crossover switch
From: "Tom W8JI" <w8ji@w8ji.com>
Date: Wed, 27 Jun 2007 10:17:21 -0400
List-post: <mailto:amps@contesting.com>
> 3) the contacts area seems not so large, especially the NC 
> contacts
> (but I will use two in parallel)

No matter what the relay, the actual contact area that 
touches is very small. The big area gets rid of heat 
however.

> 4) when the coil is energized, the moving contact press 
> the NO fixed
> contact using only its elastic force (not pressed by the 
> armature)

This has to be. Otherwise coil voltage would affect contact 
pressure. That would be a poor design. Relays always have 
some sort of spring or spring action that controlls contact 
pressure. It is often designed so the contact rubs a small 
amount when closing and opening.


> 5) when the coil is not energized, the moving contact 
> press the NC
> fixed contact using the elastic force of the armature (it 
> is pressed
> by the released armature)

Good design. This makes pressure equal and controlled by the 
contact support which doubles as a spring.

I see the pictures now at the link. The relay you have is 
similar inside to relays that are very effective for RF. I 
normally just use SPDT because the contact connection path 
is larger. That is where most of the RF heating will be.

73 tom



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