[TowerTalk] remote switching for balanced lines

[Gary Schafer]

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Jim Lux
> Sent: Friday, April 11, 2008 4:50 PM
> To: Gary Slagel
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] remote switching for balanced lines
> 
> Gary Slagel wrote:
> > Anyone have any ideas on how to remotely switch
> > balanced lines.  The idea being to have 2
> > dipoles/doublets on a tower with one balanced feedline
> > running to the shack and be able to switch the
> > feedline from one antenna to the other at the tower.
> 
> Assuming you want to fabricate something:
> 
> Double pole double throw relay, coil operated by DC carried on the
> feedline, decoupled with a choke.
> 
> 
> Use any of the relays that folks use in antenna switch boxes that are
> available in DPDT configurations..
> 
> If you want something off the shelf, it's going to be a bit trickier.
> You could modify something like an MFJ RCS-8V pretty easily by cutting a
> couple traces.  The relays in that are basically SPST switches, so you'd
> use 4 of the 5 to do your switching.
> 
> Jim, W6RMK

You will want to have something better than the type of relay used to switch
50 ohm coax though. 1500 watts at 50 ohms is 273 volts. 1500 watts at 600
ohms is 948 volts and that is providing the swr is 1:1. 

73
Gary  K4FMX