Mounting a new satellite dish

Something that almost every radio station has but no one really thinks about; the satellite down link. I think radio stations began installing satellite down link equipment around 1982. Before that, all network programming was carried hither and yon via Ma Bell’s extensive terrestrial microwave network.

Those early dishes were almost always Scientific Atlanta 9000 series 2.8 meter antenna system, which went with the SA 7300 DATS satellite receiver.  Fast forward 31 years and things have changed.  The satellite constellation is now spaced at one degree and those old SA 9000 dishes are not one degree compliant.

Scientific Atlanta 9000 series satellite dish
Scientific Atlanta 9000 series satellite dish

Therefore, when it came time to re-aim a dish at AMC8, something new was required.  A Prodelin 1374 3.7 meter center fed C band dish was ordered up.

The first thing to do is look at the dish specifications and decide if the suggested mounting procedure is a good one.  The soil in this area is sandy loam.  The mounting design calls for six inch schedule 80 steel pipe at least six feet into the ground.  This calls for renting an excavator, digging a six foot deep hole, buying a 36 inch sono-tube and a 16 foot piece of 6 inch schedule 80 steel pipe and a couple of yards of concrete from a truck.  This work all being done on the ground system for the WDCD antenna array.  All the while, abandoning the old pad and dish in place.  Seems like a lot of money and wasted materials.  Re-using the old pad and part of the old mount seemed to make more sense.  I did some rough calculations on paper regarding wind forces, this was the results:

WDCD satellite dish mount design
WDCD satellite dish mount design

The maximum static force is 1,555 N on the back bolts of the mounting ring into the concrete pad.  Maximum wind force is 5,603 N, a maximum wind from bearing 76° T will exert a force of 7,158 N or 730 Kg force on the back bolts of the mount.  The concrete that the mounting bolts is embedded in will withstand 4,267 Kg of force at six inches deep.  The the existing pad and 3/4 inch J bolts are well within their rating to handle this load, so it seems like a good design. Putting that to practical use:

Scientific Atlanta 9000 series dish mount
Scientific Atlanta 9000 series dish mount

First, we unbolted the azimuth mounting ring and removed the old dish, leaving the bottom of the mount.  I drilled down 6 inches into the old concrete pad and inserted 1/2 inch re-bar.  These re-bar are somewhat diagonal toward the center of the tube towards the new mounting pole.

Scientific Atlanta 9000 series dish mount reuse
Scientific Atlanta 9000 series dish mount reuse

Then, we placed the 6 inch by 8 foot schedule 80 pipe in the center of the tube and attached it to the tube with 1/2 inch all-thread.  We used the all thread to adjust the 6 inch pipe so that it was vertical.

Next, we filled the old mount up with 4,000 PSI (280 Kg/square cm) ready mix concrete and let it cure for one week.

New mount for Prodelin dish
New mount for Prodelin dish

While that was curing, I bolted the new Prodelin 1374 dish together on the ground.  Follow the directions closely on this one, there are many pieces of hardware that look the same and are almost the same but will not work if exchanged.

Prodelin 1374 dish about to be lifted
Prodelin 1374 dish about to be lifted

We used a loader with a lifting bar on it to sling the new dish into place.  I was going to video tape this evolution, but we were short handed and I ended up helping bolt the dish on the mount once it was placed there.

Prodelin 1374 dish, installed
Prodelin 1374 dish, installed

Once the dish was mounted, I installed the feed horn and LNB.

WDCD Albany, NY, Prodelin 1374 dish installded
WDCD Albany, NY, Prodelin 1374 dish installed

Then there was the aiming; this dish is pointed at AMC-8, for which I found this information from dishpointer.com most helpful:

WDCD AMC-8 information, courtesy of dishpointer.com
WDCD AMC-8 information, courtesy of dishpointer.com

This is a crowded neighborhood and finding the right satellite took a bit of trial and error.

3 thoughts on “Mounting a new satellite dish”

  1. Back in the good old analogue days all you had to do was peak for max signal level or maybe best C/N. But now it’s also lowest BER (bit error rate). The BER can very greatly and the signal level will hardly change. But it makes a huge difference on how reliable the feed will be.

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