Thread: Sadoun 1.8M Polar Mount Assembly

I thought about my response, and the part where I say the arm is on the high seems wrong. The arm on the high side would be fully extended. I would think a fully retracted arm would withstand snow loads better than fully extended.

So I plan to switch the arm to the other side this morning, before doing the due south alignment. Does mean I'll need to drill another set of holes for my arm extender.



Also when I snowbird, think I'll leave my 1M dishes pointed at 87W for the same reason, let snow slide off easier. Never considered snow on them before while enjoying the sun in the desert.

On my dish i just put the clamp that slides on the mover pipe close to the dish. no drilling needed. There is very little snow build up when my dish is set that low.

BTW, the model number for this dish that wrdavis is reviewing is SD180PM: Polar Mount Style.

Thanks Iceberg.



Well today was the day to get the dish aimed and aligned.

First I had to swap the angle iron bracket to the east side, and drill the additional holes in my extender arm bracket I made. So a good amount of time was waiting for the paint to dry on my bracket. So while that was drying, I tightened up some of the bolts a bit more on the mount. I had noticed some play on the polar axis and elevation axis. But tightening cured the play and still allowed movement.

Adjusted the GeoSat dual output C Band LNB so the 0 is at 9 o’clock position. Set the f/D at .39 and finished by marking the locations for future reference.
Finally the paint dried and I bolted the angle iron bracket with my extender onto the ring & mount. Marked the angles of my most eastern & western satellites on the top of the mount, so I could make certain the actuator arm would do its job without binding or hitting something. The concept I had of the extender was it would increase the number of pulses to move the dish, resulting in more resolution.

To confirm this, I first used the stock location and with the actuator saddle clamp loose enough to allow the arm to slide measured the distance from the clamp to the edge of the actuator arm. The delta from the east most to west most was 7.5". OK should have a delta of 15” or so; all the way out at the end of the extender. But only 8”. Half an inch difference between the two deltas. Couldn’t believe it. Measured again, what a bummer. Extender bracket was a totally worthless concept. Half an inch difference, wow. So took the extender back off for my scrap metal pile. Re-connected the arm to the stock angle iron and started doing the due south satellite.

I had brought the GBOX 3000 out with me and hooked it to the actuator arm. For all my concern about where to set the actuator for the dish pointing due south, all I had to do was point the remote, push the button and run the actuator until the dish aligned with the side of the polar mount.

I plugged my self powered Digisat II meter into one the LNB outputs and discovered I had so much signal I had to attenuate it. Never with my 1M and smaller dishes have I had to do that. Next I swung the azimuth manually for peak signal. This is where I discovered the signal didn’t vary much from satellite to satellite. Must be the small 6 foot diameter and 2 degree resolution Iceberg has mentioned. The signal from one bird drops off as the next comes up. Just a total blur.

At this point no choice but to hook it up to my Pansat 9200HD and see what it said I had. But first I needed to wire a coax from the second LNB output into my switching network. I elected for this dish to use a 22KHz switch. The 0KHz side to my existing 4x1 Diseqc switch and the 22KHz side to the new C band dish. That way all the existing stuff stays the same. Change a couple connectors and ready to go.

So set the best guess on the azimuth and discovered I had 127W Galaxy 13 in my sights. Tuned to LCN, the Louisiana Super Station, and thought of Tron in New Orleans. So I was 8 degrees off. Calculated the inches per degree around the 76mm mast and went out with a ruler and marking pen to set where 118.7 Anik F3 should be located. Checked on the TV and this time was closer, but no cigar. Hit 121 Galaxy 23. Well third time did it and found Anik F3. Peaked that on the TV readout for azimuth and then for elevation. Locked down the adjustments and brought my stuff inside. The rest was an indoor job of locating the satellites and storing their locations into the GBOX.

A number of hours later and a couple mis-steps with wrong 22KHz settings in my channel list on a couple birds, and I had all from 87W to 139W stored and channels scanned into the Pansat.

I like the way the GBOX displays the satellite location by name. After the birds are entered, and doing a manual move the display counts up or down and switches to the name when its hit. But have to say using the name to select which one to move to takes more time than just entering the two digits for the location and hitting OK. Tried the by name way, and you need to scroll through all the choices until you find the correct one. Heck by the time you find it, the antenna would already be in place with the 2 digit method. Also surprised me with how fast the actuator moves from satellite to satellite. But it’s only using 7.5” of the 24” available to swing 52 degrees. I think this dish moves faster than my 1M dishes with Diseqc motors.

After getting all the birds scanned in, my only disappointment was the NASA HD on 137W AMC7. I can’t find usable signal there. Seems NASA needs more power or something. Maybe borrow some from the North West Territories channel from Canada, they had lots.

Tomorrow plan to weed out the channels I don’t want; and try to match what’s left with TitanTV guide. Then a bit of clean up on the coax outside with ty wraps and wire in the living room unit and this project is done.

One day when I have time, I’ll plot out the GBOX count versus the orbit location and see if my notion that it’s a sine wave is valid. But I suspect the signal strength and low resolution of the 1.8M dish won’t prove much. There were some spots that I could have picked half way between two birds and still had a usable signal from both.

So here’s the wrap up pictures and a screen copy of my data for the GBOX.

Great review, Wrdavis! Congratulations on the completion of your SD180PM. These are ideal dishes for C-Band in a tight place, and also a great alternative to the ever-popular MiniBUDs. I plan to finish my review of the SD180G (ground mount model) this week...

Here's a jpg of the parts diagram for the polar mount version for reference.

Thanks for all the great pics wrdavis.

I enjoy seeing these projects coming together, excellent post.

One question perhaps you or Mr.Sadoun can answer... what is the length of the center 3" mast that wasn't used supplied with the SD180PM?

Good job .. excellent pictures.

The 3" mast was 39" high. I cut the triangular mounting plate off and lowered it to 36" for a roof mounting.