Date: Mon, 27 Sep 2010 20:50:48 -0700
From: Jim Lux <jimlux@earthlink.net>
Subject: Re: [TowerTalk] X99KP 12VDC RELAY FOR AMERITRON REMOTE
ANTENNA SWITCHES
And just how do you think they do a "double make" contact? :)
Bridge the two armature contacts on a dpdt or dpst relay and you get a double
make spdt or spst.
## whoa. P+B makes SPST-DM relays. They are configured just like any
contactor. It's 2
sets of contacts IN SERIES. The COM [ moveable part] is shaped like a 'T'...
and comes crashing
down on the TWO 'throws. One throw is the input, the 2nd throw is the
output. Contactor's
are built the same way, except times two or three. The concept is when
shutting off stuff like
motor's, etc, the back emf is split into TWO gaps, = zero arcing.
## IF you take a DPDT or DPST relay, and parallel all the contacts, you just
get a
higher current rated SPDT or SPDT. I dunno if you would call it DM. I
would call it
redundant contacts. It's an excelllent config, when using mech realys for
remote switch's.
If you double the current rating, you quadruple the power rating. The way the
poer can go open is
if both contacts go open.
## The only other config that is reliable is vac relays.
Jim VE7RF
On Sep 27, 2010, at 8:39 PM, "Ron W8RJL" <youngron@verizon.net> wrote:
> For anyone who might be confused by the armature and parasitic verbage here
> is what Allan Bradley has to say about Form X relays:
>
>
> A Form X contact arrangement is one which has single-pole, single-throw,
> normally open double-make contacts. The function of this arrangement is to
> close a circuit when actuated.
>
> Forget about parasitics and armatures. It is just a contact configuration.
>
> 73,
> Ron W8RJL
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