Channel Master 1.8 Restoration

[s-band]

Part 1 of n?

Thanks, Captain Jack, for this: Bargain Second-Hand Big Dishes For Sale

Pictures of it in its younger days: Channel master 1.8M Dish

I collected it yesterday. Even with 3 people it wasn’t easy to lift off the pole mount. I was warned that they are heavy! You can probably see from the original listing that the pole mount is about 2” and the polar mount takes a 3” pole so I'll need a new ground stand.

In the light of day the dish itself doesn’t look too bad. However, the polar mount, or maybe the whole thing, has suffered quite a whack. The pole sleeve is not in line with the rest of the mount. Some bent bits are easy to spot. It’s hard to see from the photos but the two plates either side of the adjuster are bent away from being perpendicular to their base. I’m not sure how to straighten it yet.

The arms are obviously bent and the jack looks like Crossbones original. I’ll add that to my collection of duff Superjacks. So, for now, I’ll stare at it for a while and trawl through the CM threads on here for tips on restoration.

 

[Captain Jack]

Whoohoo! Glad it went to a good home! What are your plans with it? C? Ku? Ka? L? All of the above?

 

[RimaNTSS]

I do not see problems with dish itself, even label is in good shape. Polar mount is easy restorable (brush/ sandblast and then paint). Feedarms- better to make them completely new. For the ground stand I would recommend something like I have here (~600kg of concrete and metal support which allows to make pole plumb).
But, congrats, you've got nice toy.

Add: I installed my dish alone, I mean, it is doable.

 

[Captain Jack]

Doable for those weightlifters at the Olympics... It's a heavy dish and not only that, it's a big dish. My Laminas is relatively light (half the weight) and it was still tricky to bolt it on due to the sheer size of it and lack of handle to grab hold of. Had to get the other half to help me...

Is there a method to lifting them? Maybe I am doing it wrong. I want to try the CM in place of Laminas for comparison but I am very discouraged by the weight etc...

 

[s-band]

Whoohoo! Glad it went to a good home! What are your plans with it? C? Ku? Ka? L? All of the above?

Thanks, Ku & Ka probably. I'd like to use the SMW PLL with mechanical polar rotor as it may be better than trying to fit it to the IRTE.

I do not see problems with dish itself, even label is in good shape. Polar mount is easy restorable (brush/ sandblast and then paint). Feedarms- better to make them completely new. For the ground stand I would recommend something like I have here (~600kg of concrete and metal support which allows to make pole plumb).
But, congrats, you've got nice toy.

Add: I installed my dish alone, I mean, it is doable.

600kg concrete - can you lift that as well? I need to retain portability in case of planning problems but I have some granite blocks to hold it down. Yes, the dish is better than expected. The line that looks like a crack on the photo of the back is a cobweb. I have straightened the feed arm by squashing it in a Workmate which distributed the pressure. It still needed more bending which I did iteratively; bend, rotate, bend, rotate etc until it was reasonably round. It still has some ripples but it will do to start. I'll think about new arms if/when I try a fancy feed rotator. There is only some rust on the polar mount near the bearings and fixings, I think I'll get away with so localised rust prevention.

The polar mount has less problems than I thought initially. I don't think it has been bent. Many of the fixings were loose and had been for some time which resulted in some damage to threads as it waved about. The plates either side of the polar axis member are skew but mis-alignment was mainly due to the holes marked yellow being 13mm diameter fitted with 12mm bolt. I've ordered a 1/2" bolt to replace it.


I'm missing a plastic bit to hold the lower feed arm.


I'm thinking of getting the matching C120 feed. Has anyone bought from here? Channel Master Feed Horn (cheaper than UK suppliers) and wondering if I can add inclined tracking to this easily:

 

[scopus]

Thanks, Ku & Ka probably. I'd like to use the SMW PLL with mechanical polar rotor as it may be better than trying to fit it to the IRTE.



600kg concrete - can you lift that as well? I need to retain portability in case of planning problems but I have some granite blocks to hold it down. Yes, the dish is better than expected. The line that looks like a crack on the photo of the back is a cobweb. I have straightened the feed arm by squashing it in a Workmate which distributed the pressure. It still needed more bending which I did iteratively; bend, rotate, bend, rotate etc until it was reasonably round. It still has some ripples but it will do to start. I'll think about new arms if/when I try a fancy feed rotator. There is only some rust on the polar mount near the bearings and fixings, I think I'll get away with so localised rust prevention.

The polar mount has less problems than I thought initially. I don't think it has been bent. Many of the fixings were loose and had been for some time which resulted in some damage to threads as it waved about. The plates either side of the polar axis member are skew but mis-alignment was mainly due to the holes marked yellow being 13mm diameter fitted with 12mm bolt. I've ordered a 1/2" bolt to replace it.
View attachment 96181 View attachment 96183

I'm missing a plastic bit to hold the lower feed arm.
View attachment 96182

I'm thinking of getting the matching C120 feed. Has anyone bought from here? Channel Master Feed Horn (cheaper than UK suppliers) and wondering if I can add inclined tracking to this easily:
View attachment 96184

I have a couple of CM feed horns spare, both in very good condition. Looking for around £25 each, plus postage. Best to message me if interested.

 

[RimaNTSS]

Is there a method to lifting them?

Instead of doing it hard I always try to do it smart. To install the dish on the already placed mount I turn it upside-down and then place a bolt in the hole circled yellow . When bolt is slightly tightened with nut, just turn dish around and finish rest of the bolts.

Has anyone bought from here?

I would resist to buy original CM feedhorn for such a price! Why not try IBU, it will work not worse than any other LNB attached to CM feedhorn.

 

[s-band]

Instead of doing it hard I always try to do it smart.

Why didn't I think of that?

I would resist to buy original CM feedhorn for such a price! Why not try IBU, it will work not worse than any other LNB attached to CM feedhorn.

I will try an IBU (Inverto Black, I presume) but I would like to be able to use the SMW LNA on it and Scopus has kindly offered a better price;-)

 

[archive10]

Doable for those weightlifters at the Olympics... It's a heavy dish and not only that, it's a big dish. My Laminas is relatively light (half the weight) and it was still tricky to bolt it on due to the sheer size of it and lack of handle to grab hold of. Had to get the other half to help me...

Is there a method to lifting them? Maybe I am doing it wrong. I want to try the CM in place of Laminas for comparison but I am very discouraged by the weight etc...

Yes it is heavy. But carrying the reflector around is best done from the backside holding the ribs in the lower part. This works for me as one person.
Two normal-height people makes the job of movnig it a doodle.

Mounting the dish is again best done by two people (although I did it myself back when my back was a lot better).
Trick is to put the mounting bracket on the pole, and incline it to about 60 degrees.
Lift reflector onto bracket roughly in the right place. Due to the angle it can be held in place resting on the bracket using one hand each person.
Adjust until dish is roughly where it should be for bolt to attach to bracket.
Carefully align holes in dish with bracjket until bolts can be pushed through bracket holes.
Put the bottom two bolts in from the back (yes, it's the wrong way, but it aligns the holes!)
The reason for this is that you can stand "behind the dish" while holding it, and see where the holes aling (this is not possible from the front).
Carefully let go of reflector.
The weight of the dish will hold the bolts in position (don't attempt this in windy conditions!)
Put the top two bolt in the reflector from the front.
Add washer, locking washer, and nuts to back of top two bolts, and hand-tighten.
Reverse the bottom two ones.
Add rest of washer, locking washer, and nuts, and tighten nuts according to manual.

Then gently decrease inclination to normal 20-something (geometrically almost vertical).

There are variations of the above; you can put in the bottom two bolts and lift the dish straight onto the mount if you fancy fiddling around with the reflector. This can be done with one person lifting, and someone else guiding the dish to the right spot where the bolts will slide onto the mount. And so on.


If you are three people, it's much easier again: Two people lift reflector, third person puts bolts through holes and tighten nuts.


On the 2.4, and even more so on the Prodelin 2.4, you can recline the mount to having a horizontal dish face.
This allow dish to be assmbled from its petals/halves straight onto the mount...

 

[archive10]

Instead of doing it hard I always try to do it smart. To install the dish on the already placed mount I turn it upside-down and then place a bolt in the hole circled yellow View attachment 96192 . When bolt is slightly tightened with nut, just turn dish around and finish rest of the bolts.

Very clever, even better than my approach. Very good!

But this will only work if you have the dish down low enough.

 

[RimaNTSS]

But this will only work if you have the dish down low enough.

It is not a big deal if installation is up to meter higher, always possible to put dish on the chair or table and hang it on one bolt. But, of course, 2 or 3 persons are always better.

 

[archive10]

I would resist to buy original CM feedhorn for such a price! Why not try IBU, it will work not worse than any other LNB attached to CM feedhorn.

I fully concur. My tests of a handful of Ku LNBs on the CM180 (elsewhere on this site) clearly showed that the CM feedhorn + C120 LNB (Iverto and Invacom) was outperformed (at least on lower frequencies) by several off-the-shelf LNBs,
The out-performers included the Inverto Black Ultra (quad and single), as well as the budget priced Maximum XO-11.
So don't go buy the CM feedhorn, unless you have a very good Ku-band C120 LNB you are dying to try (like the SMW).

(I may be stating the obvious, but you can't use a Ku-band feedhorn on a Ka-band LNB, should you wish to try that. And I don't think CM makes a Ka-band feehorn for the CM180...)

 

[CROSSBONES]

Glad it's gone to a good home and a member on here. If it's the same actuator, then it wasn't man enough to pull the dish back from the Western satellites.

Will look forward to seeing the finished results.

 

[scopus]

Glad it's gone to a good home and a member on here. If it's the same actuator, then it wasn't man enough to pull the dish back from the Western satellites.

Will look forward to seeing the finished results.

The Venture actuator I have along with other members here pulls the CM back with ease...
Nice to see your old dish again Crossbones...

 

[s-band]

I fully concur. My tests of a handful of Ku LNBs on the CM180 (elsewhere on this site) clearly showed that the CM feedhorn + C120 LNB (Iverto and Invacom) was outperformed
Ku-band feedhorn

I'd seen the comparison which is very interesting. The only offset Ku feed I have at the moment is an un-butchered octagon PLL LNBF . I'll try that to start with.

I have got an offset linear feed for Ka with circular WG to WR42 adapter but only an old band C LNB which works from 19.9 to 20.8GHz

If it's the same actuator, then it wasn't man enough to pull the dish back from the Western satellites.

Your Super Power jack is just a rusty blob now. I don't think it's been moved for years.

 

[s-band]

I had a first pass at cleaning it. There are a couple of cracks, one on the edge which must be due to a bang, the other about 100mm to the right of the sticker. There is no evidence of either on the back. I don't think there will be any impact on performance as the crack on the face is <0.1mm wide and about 100mm long (see close up). Running a finger over it, I can't feel anything. It looks longer in the photo as there is a dark mark in line with it. I'm a bit worried that frost damage, due to water ingress, may be a problem in the longer term. I'm tempted to put it in the shed for a while to dry out and seal the cracks with clear lacquer.

Thoughts?

 

[archive10]

I had a first pass at cleaning it. There are a couple of cracks, one on the edge which must be due to a bang, the other about 100mm to the right of the sticker.

Thoughts?

I'm fairly confident in saying that there the cracks will make no difference to reception or longevity of dish.

The cracks seem to appear when the material is stressed (i.e. bent or hit). But I don't quite see how the surface one can result from bending the dish - it probably caused by hitting the dish with a metal object (or vice versa). It is probably only the dish surface (pure plastic layer) that is cracked.

Don't think you will have that much a problem with water ingress, it's probably just a surface feature.

The cracked rim may be an issue if it's exactly where the arms attach, otherwise it will only have meaning if you expose the dish to gale-force wind (top of tall building) and STILL expect it to be providing tip-top reception (eg communal tv downlink facility). But I don't think you need to worry. There no reception going on in that part of the dish.

See picture below for a *proper* crack in the rim of a CM120 - notice the frayed fibres stickng out...



This was most likely caused by dropping the dish (from considerable height) onto the dish arms, or hitting the ground with the top of the dish. The dish arms provide added rigidity to the bottom half, making the dish flex in the rim just above the arm attachment points. (There is a similar crack on the other side of the dish).

If you really are worried, you can fill the edge crack with the resin-like repair-stuff also used for cars.
Other members on the site has done this before, I seem to remember a CM120 repaired in this way.

But honestly, just put the dish up, and repair only if it gets a lot worse.

 

[s-band]

I'm fairly confident in saying that there the cracks will make no difference to reception or longevity of dish.

The cracked rim may be an issue if it's exactly where the arms attach, otherwise it will only have meaning if you expose the dish to gale-force wind (top of tall building) and STILL expect it to be providing tip-top reception (eg communal tv downlink facility). But I don't think you need to worry. There no reception going on in that part of the dish.

But honestly, just put the dish up, and repair only if it gets a lot worse.

Thanks. It's not a very harsh environment here. I had a 3m PF for a few years that survived with the ground stand held only down with bricks. The edge crack is well away from anything important like the feed supports. I think it must have been lowered to the ground a bit too fast at some time. I agree that the crack in the face was probably done by something hitting it especially as there is a mark with no damage in line with it.

I've ordered new stainless fixings for the mount but need to work out how to do the ground stand. Until then I will try it on its back.

 

[archive10]

If you just want to have a quick play with the dish, the tyre-trick has been rewarding for 4wd on his new CM180:

Advice Needed - CM 180 temporary install

 

[s-band]

I assembled the arms and they seem to have been straightened ok. With the dish on its back I checked the sky noise vs. the level with the LNB pointing at cold sky. The Octagon LNBF lost about 0.5dB in Y factor and the SMW on CM C120 feed lost a bit less. That corresponds to about 0.3dB added to the LNB NF. I'm not sure I had the feed at the focus but there may be something to be gained tweaking the feeds as they may be over-illuminating slightly. (see Just Sharing This - Invacom 0.3dB vs. Octagon PLL vs. SMW PLL Ku LNBs for figures of LNBs alone)
The stainless fixings have arrived. Now I need to do something about a ground stand. I should have bought the IRTE 1.5 stand that I posted here and modified the polar mount to 4.5". It needs an 80mm pole which is a pain. I will try Purplesat and the local blacksmith but 80mm doesn't seem to be available from stockholders and I see SSS offer a shim from 75mm.
The other thing that worries me a bit is that it only has one ring of fixing bolts on the sleeve. Id prefer some top & bottom.