When I first read this I thought, "yet another ham overengineering thing".
Then I actually did the engineering.
400' of 12 AWG annealed is 0.635 ohms, whould would drop approximately 2.5
volts at 4 amps.
The same run with 16 AWG would drop about 6.5 volts.
The same run with 10 AWG would drop 1.6 volts.
I came to 2 conclusions:
1. Rotator motors should be designed for 24, or better, 48v!
2. 12/2 is a reasonable compromise, though 10 AWG wire is only about $0.10 per
foot more.
Al
AB2ZY
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Andreas
Hofmann
Sent: Saturday, December 01, 2012 2:35 AM
To: 'towertalk@contesting.com'
Subject: [TowerTalk] Rotator cable and mast questions
Hi group,
I am in the final stretch of getting my DB18 up onto a MA 550. Rotator arrived
today, its an alfa spid RAK, top mounted. Questions:
1. What rotator cable? I am trying to figure out what rotator cable
requirements there are. I know it can draw 2 to 4 amps at 12V. My run will be
roughly 200 feet from controller to rotator. I am thinking a 12-2 (2 wire 12
gauge) cable and a smaller one for the sensor. Is 12 gauge adequate for this
length?
2. What mast material? I need a 3 - 4 feet mast below the rotator and
another 3.-4 feet mast between rotator and antenna. Went to Home Depot, they
have galvanized 2 inch water pipe (with 1/8 " wall). Is that adequate. Its
called schedule 40. In K7LXC's book I read that either "for small antennas or
mounted right on top of tower, I can get away with pipe". Schedule 40 seems to
have a yield strength of 30,000 lb/inch^2. Will this be strong enough for my
application? If not, what are other good places to purchase drawn aluminium
tube? Plumbing supply?
Thanks, Andy
KU7T
_______________________________________________
_______________________________________________
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
|