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[TowerTalk] Switching 450 ohm twinlead?

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Subject: [TowerTalk] Switching 450 ohm twinlead?
From: (Henry A Pollock)
Date: Fri, 6 Jun 1997 10:53:23 PST
Re all the recent posts about the RCS8V coax switch.  How is the best way
to remotely switch 450 ohm twinlead?  I will have 3 arrays which are fed
with twinlead.  I want to individually switch these to an outside remote
matching unit before changing to 50 ohm coax.  I already realize that
using a nonmetalic enclosure is the best way to prevent impedance bumps
and stray RF.  The main question is should I use one double pole relay
(DPDT) to switch both leads, or use a separate single pole relay (SPDT)
for each lead.  Using a DPDT relay has both leads close (anywhere from
3/8 to 1 inch, depending on relay size) to the same relay coil and I'm
concerned about the overall affect on the impedances.  Using two
separate relays provides the ability to separate the leads and maintain the 1 
inch spacing, or increase it, and at the same time the relay coils
can be positioned to reduce stray inductances.  Anyone have any
experiences or thoughts on this?  Does anyone (Antenna Mart, Dunestar,
etc.) make such a unit?

Henry Pollock - WB4HFL
Raleigh, NC

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