The conductors are 18 gauge so the net resistance is within M2 specs.
> Date: Thu, 26 Jul 2012 15:21:14 -0700
> From: lwloen@gmail.com
> To: guy_molinari@hotmail.com
> CC: towertalk@contesting.com
> Subject: Re: [TowerTalk] Resistance of Rotor Control Wires (see also CAT5
> thread)
>
> Thanks, Guy. I also got a private communication that included the
> manual (gee, read the manual, who'd have thought?). The manual
> suggests that I'd want 14 gauge wire for the main rotor control and
> still 22 or 24 for the reed relays. It also suggested a rule of thumb
> that if I wired two 16 gauge together in parallel, it would be the
> equivalent of 13 gauge and (though it doesn't say so) that four 16
> gauge together would be (presumably) 10. So, if I go by the M2
> manual, I presume your scheme works provided the sprinkler cable was
> in the 20 gauge range. Neat trick, I'll consider it.
>
>
>
> Larry Wo0Z
>
>
> On Thu, Jul 26, 2012 at 2:52 PM, Guy Molinari <guy_molinari@hotmail.com>
> wrote:
> >
> > I use 10 conductor sprinkler wire (Lowes' or HomeDepot) for the 300+' runs
> > to my M2 rotators. 2 groups of 4 conductors tied together for the motor
> > control lines. The 2 remaining conductors are for the reed switch sense
> > lines.
> > 73,Guy, N7ZG
> >
> >> Date: Thu, 26 Jul 2012 14:44:01 -0700
> >> From: lwloen@gmail.com
> >> To: towertalk@contesting.com
> >> Subject: [TowerTalk] Resistance of Rotor Control Wires (see also CAT5
> >> thread)
> >>
> >> I am trying to understand control wire (DC) resistance losses. This
> >> would be for my rotor control wire for my M2 atop my
> >> soon-to-be-erected 72 foot tower.
> >>
> >> I figure my total run is going to be fairly long -- about 215 feet
> >> (for a variety of reasons, a straight cable run is not in the cards --
> >> I have to go around my septic field and a shed). The specs for the M2
> >> rotor http://www.arraysolutions.com/Products/m2rotators.htm . . .show
> >> the minimum cable gauges are 2 at number 18 and 2 at number 22. This
> >> probably relates to the total amperage delivered and the planned
> >> voltage drop the unit can stand.
> >>
> >> Calculations given here:
> >> http://www.stealth316.com/2-wire-resistance.htm . . .are suggestive
> >> that I would want more like number 12 gauge if I wanted to keep the
> >> voltage loss to half a volt (apparently, the M2 design can stand a bit
> >> more?). There are a couple of other sources, including this one:
> >> http://www.mogami.com/e/cad/wire-gauge.html which, while it
> >> dispenses with the "circular mills" part of the calculations (at least
> >> overtly) seems to me to create a similar conclusion.
> >>
> >> This suggests to me that I should be looking at some hefty cable
> >> gauges if I want to be "really sure" of things working, but I get the
> >> impression that this is probably overkill, given what M2 itself seems
> >> to be recommending. A 72 foot tower would have a minimum run (if one
> >> wanted to keep the shack out of the fall zone) of about 150 feet for a
> >> 75 foot total tower exposure. And, I know M2s are popular with
> >> VHF/UHF hams, where a lot of towers are taller still. I'm sure lots
> >> of M2s have 200 plus foot runs.
> >>
> >> Still, in line with my overengineering of the project, what I probably
> >> would find ideal is some sort of four wire shielded cable at somewhere
> >> between 12 and 16 gauge if I could find such a thing. Or, would
> >> unshielded with a couple of ferrite beads at nor near the rotor be
> >> enough? That would simplify things quiet a bit.
> >>
> >> CAT cable looks suspiciously narrow gauge for my run, at least.
> >>
> >>
> >> Larry Wo0Z
> >> _______________________________________________
> >>
> >>
> >>
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|