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Linear Actuators for tilting antenna mounts?

Discussion in 'Mobile Radio Systems' started by KC8QVO, Oct 29, 2015.

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  1. KC8QVO

    KC8QVO Ham Member QRZ Page

    Does anyone have experience with using a heavy duty linear actuator, such as one with a 200lb+ dynamic load rating and 6-8" stroke?

    I am looking in to them as the drive unit for a tilting antenna mount for my truck. What I want to do is fabricate a rack that sits on the front of the bed rails, behind the rear window, of my pickup. The rack would be hinged about half way up and a linear actuator would be used to raise/lower the top half with the antennas on it.

    The unit would have to be run every day to get in/out of the garage so reliability is a big factor. I am not sure what to start looking at. Are any of the lawn/garden grade actuators worthy of the task? Ones such as these:

    http://www.amazon.com/Stroke-Linear...46084566&sr=8-12&keywords=12v+linear+actuator

    http://www.northerntool.com/shop/tools/product_200622242_200622242
     
  2. REASTON

    REASTON QRZ Member

    Wouldn't it be easier to just do it by hand. There are literally hundreds of thousands of actuators sold for just about every mechanical need. But actuators can be tricky. What force they can move and hold can be very different. You would do well to talk to an application engineer at one of the bigger manufacturers and tell them what you want to do. I used to talk to 10 of them a day before I retired from my engineering management job. Those people know their products very well. And most of them are very friendly.
     
    NH7RO likes this.
  3. KK4YDR

    KK4YDR Ham Member QRZ Page

    You are asking exactly what I want for my Scorpion SA680 18lb antenna.

    I want to push a button and it go down. Tarheel has the Lift-n-Lay which is a $450.00 item you are asking about. You can use that for a design idea and as long as you do not go to market with it you will not violate patent law.

    I am thinking of getting a metal shop to fabricate me a mount with a bearing and I can buy an actuator off ebay for about $35-60 bux.
     
  4. KC8QVO

    KC8QVO Ham Member QRZ Page

    The Tarheel mount won't work for an idea. See below for what I am talking about. This is a very ROUGH sketch, non-dimensional, but shows the operational/functional goal. It isn't one antenna that I want to tilt, it is a whole rack with a few antennas on it.

    Manually tilting is going to defeat the purpose. I have to get out to take my magnet mount antenna off the roof and the whip off my screwdriver (quick disconnect) - its a pain, especially with any precipitation. The idea is to have all my regular antennas on the rack so I can flip a switch = can stay in the truck while I park.

    [​IMG]
     
  5. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    First of all, headache rack mounted antennas are not the stuff of champions, albeit lots of folks believe they are. Think about the lack of a proper ground plane.

    Over the years, I've seen about every kind of gadget used to folder antennas. All of them have at least one drawback. In this case, think what will happen when you forget to fold it over?

    So what do you do? I don't know how many antennas you intend to mount on said fold-over arrangement, or even their frequency. If it is just VHF/UHF, and you just have to have a gain antenna, then use the hood seam instead. Signal wise, you'll never notice.

    If the antenna is an HF one, the the headache rack idea is real a poor one, again due to ground losses.
     
    K0UO likes this.
  6. KC8QVO

    KC8QVO Ham Member QRZ Page

    Lets leave the rf side out of the equation, please, among other considerations. I am well aware of the challenges. My question and thread here should strictly pertain to the drive mechanism and mechanics of the device.

    Yes it is not the "best" solution for RF or perhaps others' views of functionality, but in my case I am building it to suit a need and specific functionality for my circumstances, not others.

    Thanks for your understanding. Any other off-topic questions, information, or criticism please PM me. Thanks!
     
  7. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    Here is a fact of life, and I alluded to it above! Sooner or later, you will forget to lower the device with predictable results.

    I did almost EXACTLY what you are contemplating. My advice to you is simple. DON'T!
     
    WA8FOZ likes this.
  8. VE7VTC

    VE7VTC Ham Member QRZ Page

    Perhaps spring loading the upper half of rack and use a motorized cable pull towards the back of the vehicle. Then if you forget to put it down, the rack will push over on the spring. It would be under tension when in the down position but it may not be too much if done properly. You could also just use a quick release pin to lock it in the up/down position.
     
  9. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    I don't mean to harp on this like is was a dead horse, but I've tried just about everything, including the spring idea Bill mentioned. I even went to the trouble of purchasing a proximity detector, to tell me if the antenna was still erected. When that failed a couple of times, I hung a sign on the garage door to remind me about the antenna being up. That worked, but I still broke more stuff than I wanted to. The only saving grace, was to machine break-off sections into the mast, and the quick disconnect. That at least solved the major damage issues. No matter, all of it is just waste of time and effort.

    If you JUST GOTTA have motorized lay over, then do what my friend Bruce suggested. Modified your garage door opener with a remote switch which will not allow you to open the garage door unless the antenna is folded over.
     
    K0UO and WA8FOZ like this.
  10. KF5FEI

    KF5FEI Ham Member QRZ Page

    There was an article in QST or somewhere about a year ago where someone had done this -- but it was just the top rail of the headache rack that was hinged, IIRC.
     

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