Channel Master Type 900 (.9 meter) Rehab

[GrumpyGuy]

After seeing the impressive results of dish projects by other Satguys (the Primestar fans in particular), I was inspired to undertake one of my own. Thanks for all the great ideas.

Here's how it all came together ...

I made a few calls to satellite system installers in the area to let them know I was interested in picking up a few used dishes. One happened to have a few dishes in the back of his van, which were destined for the dumpster behind his shop at the end of the day.

I met him at his next service call and came home with a .9 meter and .75 meter fiberglass Channel Master with Norsat LNBs - a little rust, a lot of grime, some UV damage to the fiberglass on the backside, but worth putting some time and money into.

I chose to focus on the .9 meter. The Norsat LNB was removed from its feedhorn and replaced with a QPF-031. The rotted O-ring sealing the feedhorn cover was replaced with a new one sold as a Delta faucet replacement part.

The Channel Master mount is impressive, but all wrong for a motorized FTA setup. My latitude is such that I did not need much elevation adjustment. This made it easy to keep things simple. The existing mount was replaced with a piece of 1 inch pressure treated plywood. If the fisherman's scale I used is to be trusted, this shaved about 14 lbs. off the total weight of the dish.

After a few coats of paint it was all mated to a SG2100.

If I was doing it all over I would have mounted the dish higher with respect to the motor. This would put the output bearing of the gearbox closer to the dish's center of gravity. But as far as I can tell the SG2100 isn't having any problems handling the load. If any problems crop up I'll replace the SG2100 with an HH90.

Before and after pics attached:

 

[gabshere]

looks great , gives me a few ideas about reworking my mount.
thanks

 

[1inabillion]

Good Job :up

 

[Tron]

Great work GrumpyGuy! That is the first time I've seen the QPF Invacom mounted to a Channel Master feedhorn. Looks like a great fit! I have the 1 meter version of that dish aimed at G-10R (fixed) with a high-stability Norsat LNB set to vertical polarity mounted to it.

 

[mastermesh]

Plywood for the mount on the P* - Ingenious!!!!

 

[GrumpyGuy]

Thanks guys.

I started out using plywood for prototyping, thinking I would use aluminum for the finished product. Securing a suitable piece of aluminum stock at a sane price proved difficult so I rationalized - "Good enough for the Spruce Goose, good enough for my dish!" It's strong and light, rot resistant, and has reasonable dimensional stability (if pressure treated and sealed.) ... but to be honest, if I had aluminum on hand I would have used it instead.

There was a tolerance issue with Invacom QPF and the Channel Master feedhorn. The mounting holes do not line up well enough. There are 8 holes in each I could only get 4 of them to line up closely enough to thread the screws. Fortunately those 4 were 90 deg. apart and I am confident the two are sealed well. I'm not sure which of the two pieces is out of spec, but judging by the sloppy welding on the feedhorn I'm guessing Channel Master missed the mark.

As Tron knows, those Norsat LNBs that came with the dishes have great specs. If only they were polarity switchable I would have given up circular capability and stuck with the Norsat. I'll probably use the .75 meter with its Norsat LNB as a fixed position and fixed polarity dish as Tron has done with his 1 meter.

 

[GrumpyGuy]

Weatherproofing stuff - A few products I'm sold on;

Never-Seez: A great anti-seizing compound. I use it on anything I'm bolting together that gets hot and/or wet. For satellite stuff I put it on the motor mounting bolts. Prevents rust, galvanic pitting, and galling of the threads even with repeated torquing, loosening and re-torquing. A little goes a long way, indefinite shelf life - I've been using the same can for decades.

Rubber Mastic Tape: Soft stretchy rubber strips. I'm still using hex-crimp coax connectors. This stuff seals them up airtight. A bit of a pain in the butt to work with as it likes to stick to itself and is sticky on both sides. Keep it warm for best workability. Wrap it clockwise around the connector so it tends to tighten rather than loosen the nut. Start at the bottom and work up so the layers lap like shingles on a roof.

Liquid Electrical Tape: Messy stuff. At least two coats needed for good coverage, but a good alternative to the rubber mastic when I just can't get my big pork sausage-like fingers into the space I need to work in.

... a general observation about DiSEqC switches - A far as resistance to the elements goes most switches seem to have a weak spot. The housings tend to be good solid corrosion resistant die cast metal. The back of the switch is a different story - a thin bit of plated steel, wave soldered in place - they rust, they leak, the switch fails. Using a popsicle stick I "butter" the back of my switches with silicon caulk, mounding the caulk up just slightly so it oozes a bit when screwed down. So far this seems to be working great.

In the switch pic you can see the rubber mastic tape and a little bead of caulk around the back of the switch.

 

[Tron]

Great tips GrumpyGuy. Nice thing about the wooden mounting plate, it provides a nice mount for your switch