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Aerial (roof) rotating antenna operation?

Discussion in 'General Electronics Discussion' started by Benny7440, Mar 4, 2017.

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  1. Benny7440

    Benny7440

    88
    1
    Jan 14, 2016
    The particular case here is one of those systems where you have a light antenna on the roof, a little box inside controlled by a remote control for rotating clockwise or counterclochwise and the antenna connection and box is through a single coaxial cable.

    My questions are:
    1) is the box sending a decodifiable signal through the coaxial cable or,
    2) is it a wireless communication that exists between the box and the antenna motor?

    In the case it's through the coaxial cable, if the controller box (the one at the living room) is damaged but the motor is working ok, how can I control the motor (forward/reverse) even if I've to use another pair of cables for the purpose?

    Thanks in advanced for any help on this!
     
  2. Audioguru

    Audioguru

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    691
    Sep 24, 2016
    The coax cable probably uses DC in it to drive the motor and it changes polarity to reverse the motor. The cable has a coupling capacitor to pass the signal and inductors in series with the motor so that the motor does not short the signals.
     
  3. Benny7440

    Benny7440

    88
    1
    Jan 14, 2016
    Thanks for replying, Audioguru!

    That's a good explanation, it's a shame that I don't see any labels or engravements to give more details. Nonetheless, I think, since it's all taken apart, that my best chance is to put another dc motor (if I can find a suitable one) & bring four cables to operate both thing: zignal transfer & motor control.

    Do you agree with this approache?
     
  4. Audioguru

    Audioguru

    3,084
    691
    Sep 24, 2016
    The existing motor should be fine, it needs only two wires for forward and reverse. The signal needs a coax cable. The antenna might need a balun to match it to the coax.

    About 50 years ago I had the largest TV antenna in my neighbourhood with a rotor. On one channel I could pick up a distant station in one direction and another distant station in another direction. Apartment buildings caused ghosts on many local channels but I could rotate the antenna to pick a reflected signal that was the best. I received some FM stations that were so far away that I needed a map to find where it was. Then cable TV replaced it and I can see channels all over the continent in their different time zones.

    De-scrambling pay-per-view was fun and easy.
     
  5. Benny7440

    Benny7440

    88
    1
    Jan 14, 2016
    The problem is that there's no motor... Have no idea as to how fast was it rotating much less the power output (torque) provided by it nor the mechanism that joined the motor with the antenna.
    .
     
  6. davenn

    davenn Moderator

    13,765
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    Sep 5, 2009
    so where is the motor ... has some one else removed it ?
     
  7. Audioguru

    Audioguru

    3,084
    691
    Sep 24, 2016
    Then throw it away and buy a new antenna rotator.
     
  8. Bluejets

    Bluejets

    4,486
    955
    Oct 5, 2014
    Might pay to look if a masthead amp is currently being used or required as most of these operate on DC these days. Although ac powered units are still available.
     
  9. Benny7440

    Benny7440

    88
    1
    Jan 14, 2016
    1. I found a couple of dish-rotators from microwave ovens that work & found that they've pretty good torque for the task. It doesn't need to be directly coupled to the small mast so the strain to the plastic pinnions inside can greatly be reduced.

    The only inconvenience is they're AC powered (115 VAC). I'll keep looking for other options!

    Thanks for replying to all of you!
     
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