|An easy way to set the dish elevation|
|Your dish needs to be aimed in 2 different directions in order for it to point precisely at the Astra 2 satellite system: it needs to point to the correct compass bearing (the azimuth) and it also needs to point up at the correct angle (the elevation). The azimuth is relatively easy to achieve but the elevation of course is not. Even after using a dish for over 10 years, I still struggle to get it right. I recently heard from 2 people who had built very similar, and equally brilliant, methods of achieving it.|
|1. Bill Naulder's device|
|2. David Monkman's device (Mk 1)|
|3. His Mk 2 device|
1. Bill Naulder's device
Bill Naulder was the first to contact me and his technique so impressed me that I immediately implemented it for my own setup, so with his permission I have included it here. He bought a Silverline inclinometer (available from a number of places - just Google it, it's possible to get one for under £5 these days) and used the following technique to set it up. (There are also digital models which are more compact, but they're also more expensive. And further down this page, there's a section about using a smartphone and a suitable app. Take your pick.)
He bought a steel right-angle bracket from his local hardware store (OK then, B&Q!) and you should be able to see from the following pictures how he fitted it to the dish. The inclinometer has a magnetic base, so it can be placed on the bracket and removed when not in use. The bracket can also be removed from the dish when not required, though it could be left permanently in place. The precise method of fitting the bracket to the dish will obviously depend on the construction of your own dish. We leave that to your own ingenuity!
Now comes the calibration part, and it's really a matter of trial and error. It's also the trickiest part of the whole procedure but fortunately it only has to be done once. (It's worth taking a bit of time over because the usefulness of the inclinometer will depend on how accurate you get this initial setting.)
First, find the elevation for your home locality, using say www.dishpointer.com. Then set your dish up at home until the alignment is correct and you have a good Signal Strength/Quality reading. Having done that, you simply have to bend the angle bracket in a vice until the inclinometer shows the same degree of elevation. Thereafter, all you need to do is find the elevation for any campsite you visit (using Dishpointer again) and adjust the dish until the inclinometer shows that angle.
For when it's not convenient to access Dishpointer when on the move, Bill has printed out his own maps of Europe with elevation lines drawn on them. This map is shown for illustrative purposes only. It's assumed you'll create your own if you need one!
© Copyright Bill Naulder
One further point. If your tripod isn't fully vertical, the elevation angle will alter as you turn the dish horizontally one way or the other. In an extreme case it might be enough to significantly shift the angle away from the optimal value. Therefore be prepared to check the inclinometer reading and readjust it if necessary.
|2. David Monkman's device
A few weeks later, David Monkman wrote to say that quite independently he had developed a similar device to Bill's. His has advantages and disadvantages so I'm presenting them here and it's entirely up to you which idea you choose. David's involves a lot more work to start with because the device has to be constructed. However it is then easier to calibrate and can also be used on different dishes.
It is made with 3 bits of 2cm section wood. Each of the two outer pieces has been drilled & grooved to become the other half of a sprung clothes peg. These 2 spring clip onto the dish rim. The 3rd piece is clamped between the other 2 by a bolt & is topped by a strip of steel to hold the magnetic base of the inclinometer. To calibrate the device, the inner piece that supports the inclinometer is held lightly & turned until the inclinometer shows the local elevatiion when the dish has already been well adjusted. The clamping nut & bolt is then tightened & the slope rechecked. Thereafter, no further adjustment is needed unless the device is used on another dish (see the next paragraph). After calibration the device is removed & stored for use on the next site.
On the pictures above, it is just possible to see a score mark on each side of the centre section. This is there to allow for the device to be used with alternative dishes, eg a 60cm dish for the UK and a 100cm one for Europe, that might have different rim angles. After the dish has been aligned, the device is unclipped & stored.
Initially, David's device used a protractor which was pinned to the centre section but when he saw Bill's on this page, he realised an inclinometer would be vastly superior. So that's when he fixed a steel plate to the top.
This device is much easier to calibrate because it doesn't depend on the trial and error bending of the right angle bracket. On the other hand it does involve a lot more work constructing it in the first place.
And there's one further advantage. Once the device has been calibrated and the dish elevation is at the correct level for your current location, the metal plate will be at the correct angle to point directly at the satellite. Thus you can use it as a line of sight to check for trees or other obstructions, and if necessary move the dish to another spot. Without it, it is virtually impossible with a solid offset dish to establish for certain whether an object is an obstruction or not. Bill Naulder's idea will work with a transparent dish but not a solid one unless the bracket can be fitted to the top edge of the dish. (In fairness I should point out that Bill did offer this as a possibility by cutting a slot in the top of his solid dish for the right angle bracket to fit into.)
3. An alternative elevation setter from David Monkman.
(Rather than rewriting this description, I've just used David's own words - DS)
The new gadget allows very fine, jerk free, adjustments of the angle reading, by twisting the lock-nutted wing-nut on Threaded Rod H. This works well with the mechanical inclinometer but the iPhone app easily enables adjustments as small as 0.1 degrees.
The clamping, to dish rim, is now done with a wing-nut to be more secure
Clearly it is not worth buying an iPhone just for this but if you already own any smart phone then downloading the free app "iHandy Level" is precise to 0,1 of a degree. (There are other such apps in Android or iPhone app stores.)
I'll describe the images in order,
Fig 1 is my new gadget holding the mechanical inclinometer.
Fig 2 shows the iPhone clearly indicating 24.7 degrees.
Fig 3 depicts the various parts.
(Click an image for a larger clearer view. Use your browser's Back button to return to this page.)
© Images copyright David Monkman 2012.
The pieces of wood are cut from a piece of 25 x 15 mm. This size is not critical.
A Bottom clamp 50 mm long
B Top clamp 120 mm long
C Off-cut from B glue & pinned under it to better support E
D Plastic angle 35 mm x 20 mm (overall length 160 mm, back 120 mm long
E Wood-screw counter-sunk in tail of D & screwed into B/C
G M6 Roofing bolt 50 mm long, with washer & wing-nut.
H M6 Threaded rod 90 mm long, carrying a nut & wing-nut locked together.
This all fits onto the 35 mm rim of my Triax 1 metre folding arm dish.
For other sizes you may need slightly different wood lengths.
My threaded rod H & roofing bolt G are M6 but could be other sizes. They are held in wood B by drilling holes 0.5 mm smaller than the diameter of H & G.The metal screws then cut their own thread into the wood B. (Try it first on a piece of waste, to see how easy it is )
Wood A has a hole drilled about 3mm bigger diameter than bolt G, to allow waggle. The length is about twice the width of the rim of the satellite dish.
Clamp B & A onto the rim of your dish.
Either the iPhone or the inclinometer held onto B at the locally correct angle allows the cutting line to be drawn. Aim for a slightly shallower angle as the rod H will lift the plastic but not pull it down.
D is made from plastic angle 35 x 20 mm (B&Q <4 pounds ) as long as your smart phone plus 30 to 40 mm to form a plastic hinge,. It needs drilling & countersinking near the end to secure with a wood screw to B/C
On a well swung dish clamp the gadget to the top of the rim, mark that position to allow easy returns. Mount your smart phone or inclinometer onto plastic D. Secure with 1 or 2 rubber bands to avoid damage.
Twist rod H until the angle shown is your local satellite elevation. After this try not to change rod H as it is set correctly.
At a new location, clamp the device onto the dish as before.
Now do not alter rod H, instead move the dish elevation to match the new local satellite elevation, as found from the map in Section 4 of the Sky page or Dishpointer.com, etc.
Next swing the dish direction to maximise the signal.
Normally the ground is not absolutely level so the elevation may have changed, correct it on the dish not rod H & recheck your signal strength versus direction.
Enjoy your TV !!
Those of you who sometimes use other satellites merely change your direction & dish elevation not rod H.
Remember the plastic angle D is looking exactly where the dish looks, so you can also readily see if trees etc. are dimming the signal, by looking along the plastic.
To keep this page reasonably compact, I've limited it to just these 3 ideas from Bill Naulder and David Monkman. However, both of them have sent me various other suggestions as well, not only on elevation setting but other related topics. If you're interested, you'll find them here.