Little Tarheel II questions

Discussion in 'On the Road' started by KK6RPX, Apr 25, 2019.

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  1. KK6RPX

    KK6RPX Ham Member QRZ Page

    Hi All,

    I picked up a Little Tarheel II the other day, just the base and whip. Making a manual controller for it is simple. What I am wondering is what type of sensor it uses to detect rotation. Tarheel told me it counts the revolution of a magnet, so a Hall effect or reed switch seems likely. Anybody know for sure what it is?

    Another question: On the Tarheel site is says not to use the antenna on a trailer hitch type mount. I want to mount the antenna on the tongue of my trailer, which would put it between the car and the tear drop trailer. It looks to me that as long as I have it on a stub mast that brings it up above the roof of the car and the trailer that it should work fine. How far above the ground plane is ideal? I am not going to use it in motion so I can have it at whatever height is optimal.

    Thanks!
     
  2. WW1SS

    WW1SS Premium Subscriber QRZ Page

    Its just a reed switch
     
  3. ND6M

    ND6M Ham Member QRZ Page

    I think the manufacturer is concerned about an effective ground, a sliding ball mount (trailer hitch) is a poor connection
     
  4. KK6RPX

    KK6RPX Ham Member QRZ Page

    I have pretty good bonding between the trailer and car as I already use it as a ground plane for a WWII surplus 23' whip. I guess only trying it will tell me how well it works. The sensor being a reed switch makes it easy to work with. I think I'll make a manual controller and put an LED on the reed switch so I can count turns between bands.
     
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    The big problem with a trailer mount for an HF antenna is the lack of ground plane DIRECTLY underneath the antenna. It doesn't really matter how much metal you have bonded off to one side or the other, the image plane of the antenna is what sits directly beneath the antenna. The other problem is the low height and proximity to the ground or road. When you put the two together (poor ground plane under the antenna and proximity to the actual ground) you get high ground losses. If possible it would be better to mount the antenna on the vehicle's body up higher or even in the bed of the trailer so there's plenty of ground plane under the antenna.

    Check out Alan's site for more info on mounting options and tradeoffs: http://www.k0bg.com/antmount.html and http://www.k0bg.com/eff.html
     
  6. KK6RPX

    KK6RPX Ham Member QRZ Page

    K7TRF, thanks much for the links! Great read and I'm glad I read it before working on the install. Since I am not going to use the antenna while in motion I could mount it to the roof rack, as long as I bond it correctly. If I mount it on the front crossbar of the roof rack that puts it somewhat centered on the car although the hood is lower and I'd want to add to the bonding. I can't put it in the center of the roof as there is a 2m antenna mounted there. So is the front of the roof rack my best option?
     
  7. K7TRF

    K7TRF Premium Subscriber QRZ Page

    That sounds like a good option. You could probably configure some kind of tilt up mount (check out Breedlove mounts for high quality HF antenna mounts) so you could lay the Tarheel down when not using it or perhaps remove it when not in use. https://www.breedlovemounts.com/
     
  8. KK6RPX

    KK6RPX Ham Member QRZ Page

    Well, I worked out a good mount for the antenna that clamps nicely to the roof rack. The fly in the ointment is that there is no obvious or easy way to ground it to the roof of the car.
     
  9. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Sounds like you'll need to drill a hole in the roof and bond the antenna mount ground to the roof with a short low inductance strap.
     
  10. KK6RPX

    KK6RPX Ham Member QRZ Page

    I don't mind drilling a hole in the roof, I have an NMO mount drilled through for the 2M. What is the best way to seal it though? While I'm fine with drilling a hole, leaking not so much.
     

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