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Originally Posted by satnutwillb
I took my 18in. and slid it up through the tube some because I could go below amc-7. Now I can get over to amc-12 back to amc-7.Had to resync,but it worked.I heard or read Mike Kohl saying something about this,tried it and it worked.I can go a little farther east,but it flops sometimes.Alot has to do with location too I guess.
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Wanted to comment on a couple things here. The last line of the above is particularly important, because the range you can expect out of an
actuator depends a lot on whether you are trying to extend much past your due south satellite, ie if you're on the east coast trying to get to Atlantic sats, or in the midwest trying to get to eastern sats, or in the mountains trying to get to western sats, etc. Actuators sometimes don't perform very well when you go past the due south satellite, for 2 reasons. First, which I think is where the "flop" mentioned above comes in, some actuators have a tendency to not be able to "pull" as well as they can "push", and I've heard a LOT of stories of them completely letting go, or at a minimum skipping a gear or two so that you have to re-sync every time you go too far. Another symptom is related to free play, such that the sat will seem to be located at one "count" going east, but at another count coming back west.
However, my real reason for replying is to warn against something that I ran into years ago when I had an actuator (I now have a H-H). At the time I lived in the middle Atlantic east coast, and was trying to get to some Atlantic sats which were past my due south satellite. I was using a 24" actuator on a 10' dish, and I had considerable extension left on the actuator so that I thought I had the capability to go a little further than I was currently reaching, so I tried to stretch out the east limit as far as it would go. Luckily, I was watching the dish as I did this. What I found was that even if you have extra extension available on the actuator, there is often a physical limit to how far you can go past due south, due to the fact that once the angle of the actuator gets beyond the point where it is tangential to the surface of the dish, two things happen. First, the mechanical advantage changes dramatically, both for pushing and pulling. The mechanism actually starts to "bind", in that you are pushing away from the direction you are trying to get the dish to go, and sometimes it gets almost impossible to pull the dish back. But the second thing I noticed, is that the actuator actually started bumping into the side of the dish, so that to extend further, I was actually sort of denting the dish from behind. This was hard for me to visualize until I actually saw it happening.
There are a couple solutions to this, which I've read about people trying, but I'm not sure how effective they are. The most effective seems to be to extend the connection point of the actuator at the dish surface up, away from the dish by 5 or 6 inches, instead of having it connected close to the dish surface as is the normal way these dishes seem to come from the factory. This allows you to extend your actuator well past the tangential point, however it doesn't cure the mechanical disadvantage problem, and actually can make that worse, so you'll have to make sure that your actuator is in good condition, and doesn't have problems pulling the dish back, once fully extended.
For a 10' dish, I think a 24" actuator is recommended, both for power and extension, but for a 7' dish, an 18" actuator is probably as long as you need. However for an 8.5' dish, you may be able to get a bit further with a 24" actuator, but I'd be careful.
Whatever you do, whether it's getting a bigger actuator, changing the connection point, extending the electrical "limit" switches, or just sliding the actuator in it's bracket to get more extension, I would strongly advise watching the dish carefully the first couple times you try extending the dish to it's new limits past due south, because unexpected things can happen. Those actuators have enough power to do damage to themselves or to the dish, if you try going too far. So watch carefully for the actuator binding when going past the tangential point where it connects to the side of the dish.
Linear Mode
