Channel Master dish

[Anole]

best guess/ high probablity/ I think so:

mine measures up to be 23"... discrepancy. . . .
I wonder if the different 1m molds have different focal lengths and/or offset angles... therefor different arm lengths.

First off, I think this is the first time anyone has come up with such a unique variation on that dish.
So, we are treading some new ground, here.

I'm going with high probability that all the CM molded dishes of that size are identical and have the same focal length.
That's why I figured your lower support arm might be shorter - to move the LNB -down- to the proper focal point.
That way, the mount marking work properly, and you are at the actual focus of the dish.

Now, could the side support arms be different? Maybe? But let's consider "no", as first choice.
Is the lower LNB-holder block unique? I'm strongly doubting that, but anything's possible.

So, since you've said you want to lighten up the dish and motorize it, the upper LNB holder has got to go.
If you first just want to play with it, use it as-is, and hook to the dual-output LNB as described above (or replace it with a similar Hughes model), and just aim the dish a little to one side.

But if you want to get to the mod to restore the dish to "normal", I'd make up a longer lower support strut out of conduit or aluminum tubing from the hardware store.
Alternately, you might search the forum for one of the surplus vendors who sell replacement parts for those dishes.
(I just don't have that bookmarked)
I strongly believe, that the existing LNB holder and side support struts will work okay with a longer lower support arm.
Also, the lower is straight, and the sides are bent, so this should all go quite easily.

Side note:
One of our creative members, Dee Ann, had a similar dish with a broken/missing -side- strut
She cleverly took aluminum tubing from a broken deck chair and bent it to match her good side strut, and restored her Channel Master to tip-top shape!


PS: kudos to OSU for the invaluable support! - :up

 

[osu1991]

Well you guys lit a fire under me this afternoon. I started looking through everything I had on my laptop concerning putting a motor on these dishes and stumbled upon these manuals for the Channelmaster Dishes. I totally forgot I had them. Thought someone might want to peruse them.

Dow electronics used to have the arms for these dishes, I don't know if they still do or not.

 

[osu1991]

Thanx OSU!!!

mine measures up to be 23"... discrepancy. So I messed around a little and noticed that the dish and lnb bracket both have guides that hold the poles to a reasonable tolerance. Any change to any one pole would mean that all the poles and lnb holder would have to change... maybe even the dish. from reading on the web I have seen 2 different mold numbers for 1m dishes. 1.0M-01, and 1.0M-02. There might even be more... I wonder if the different 1m molds have different focal lengths and/or offset angles... therefor different arm lengths.

Hate to bother you again OSU, but could I get you to tell me what mold# yours is? It should be stamped on the back.

Were you measuring the lower arm with it still on the dish? I had mine off. If I measure from the tip of the lower arm at the end of the holder to the front of the of the dish I get 23inches.

 

[flyznest]

Yep OSU... I measured from end to end of the pole. its 23"

Also, the lower is straight, and the sides are bent, so this should all go quite easily.

well... there is another discrepancy... my lower leg is bent maybe 10 degrees. see the attachment...

I don't have matlab on this computer... but let me take a stab at this. if you make the bottom leg slightly shorter and bend it a small amount upwards, like mine, it will still put the lnb someplace on the focal axis... Assuming OSU's primestar has its LNB exactly at prime focus, this will position my LNB slightly inside of prime focus where the beam is wider(to accomodate more lnb's?). Now... because this relocated the lnb holder, the side supports must change to accomodate the new location... they are probably shorter than OSU's. If all of this is correct, I can easily use this with an lnb in the lower holder... it just wont get the same amount of signal as one would with a primestar. but I bet its still better than the 30" I'm using now.

or I could be completely wrong and I will just wind up going back to the dual lnb setup

PS: kudos to OSU for the invaluable support! - :up

yep... OSU is a huge help... do we have a points system on this forum so I could vote him a few?

 

[flyznest]

as I was just putting the dish back together I noticed each leg had a sticker on it... The sticker is on the end where the pole is inserted into the dish hole so its not visible unless the legs are out of this dish. The sticker, on all 3 legs, reads "1.0M offset antenna leg set". There doesn't seem to be any special marking or anything indicating that this is a modified leg set for dual LNB... but this thing has been sitting out in the arizona desert for a few years so who knows what stickers have rotted off.

 

[flyznest]

well... I have tried to upload a pic of the bent bottom leg about 40 times... each time changing the image to different sizes and formats... for some reason it aint going.

 

[Anole]

Well, I don't have a 1.0m Primestar, so whether the lower support strut is straight or bent, we'll let OSU have the last word.
The side struts have a big obvious bend in them.

We should have you measure your side strut length and compare to OSU.
I'm betting they're the same.
But, this is my theory, based on the minimum effor to make that dish of yours work with standard parts.
In other words, I suspect most parts are stock, and only the LNB upper pivot bracket and the lower LNB support arm are odd.

 

[osu1991]

Yep the lower arm does have a bend where it attaches to the reflector, just like the side arms.

I think it will work great just by removing that adapter and put one of the stock lnbs in the main holder. Would also probably be a great fixed dish with the dual holder on like 97 and 101 or 87 and 91.

 

[flyznest]

my sides are ~34.5". I measured end to end along the outside of the bend with a piece of string, then measured the string with a tape measure... so there might be some measurement transfer errors... but that should be close.

I suppose that if the side arms lnb bracket both change then it could work with the regular arms... we'll see

Without measuring the bend angles we really can't go much further than this... I think we've beat it to death... the only thing more I can do is put it on, try with the LNB in both places, and see what gets the better signal.. in either case it will likely be better than my 30"

 

[osu1991]

Yep mine are 34.5 on the sides.

 

[flyznest]

Well I made the bracket today. Took about an hour and cost $22 at ace hardware. I'm gonna try to attach a few pics... hopefully it works

I started with a piece of 8" x 9" x .25" aluminum plate. I chose 9" to give myself a little room for the jack screw. like everyone else, I used an old j bar mounting bracket as the base. The J bar in the pics was just there for the fit.. it is replaced with the motor shaft during installation. I decided to go with 2 jack screws for stability. I used a pipe clamp and some scrap alum for the jack screw brace... works very very well. The jack screws are 1/4-20 and they go through the plate and are bolted tight. Everything else is drilled out loose do they can flex around a little.

Unbelievably I just took it out, bolted it on and it worked... by some miracle the elevation must have been accidentally correct. I literally didn't make any adjustments yet and my reception is stronger on every single channel.... how many times will that happen in my life? likely never again.

 

[Anole]

I see you paid good attention to the clever members who went before.
AND added a nice twist of your own! - :up
Congratulation on a fine job.
Keep us advised on how it works out!

 

[crackt]

yes a very good attempt indeed. nice work. i like the bottom mount elevation bolts. they are really a must have with these heavy bi otches. haha.

crackt out,.

 

[flyznest]

I will definitely keep you posted Anole... I still have to go tune it but by the time I got it hooked up and noticed it already had a good course alighment.. it was too late to be messin around.

yes a very good attempt indeed. nice work. i like the bottom mount elevation bolts. they are really a must have with these heavy bi otches. haha.

hahaha... well... it really isn't that heavy once you lighten it up a lil... My friend lifted it onto the roof with one arm and he's really not that big of a guy. But having those braces stiff should help a lot

lets see how long the SG2100 lasts!

 

[ynnedibanez]

looks great:up:up

 

[osu1991]

Great job

 

[Larobpra]

Fine job! You'll find it's a great dish.

:up :up :up

 

[stogie5150]

Nice! :up

 

[flyznest]

the good, the bad, and the ugly

well... Its been through its paces.. I got a precise alignment... i don't have a blind scan receiver so I just scanned each bird on known TP lists. I've run the snot out of it on the motor looking for backlash, repeatability, and wobble... any side effects of an oversized dish. Here is what I found.

I have KU section of "The List", in its entirety, programmed into my receiver. I am getting more quality on every single TP that I had with my old 30", in some cases over twice as much, but I have gained no new TPs that I didn't have before.

I don't have the proper lnb holder cap and the one from my old fortec dish does not fit. so I'm using zip ties but as tight as i can get it, there is no real clamping force and the lnb has been shifting small amounts. This may be effecting me a little. I also don't have a 3:4 switch or whatever so right now I am using my old fortec lnb. I borrowed an old channel master sat meter and while listening to it and watcing the meter I put my hand different places on the dish to see how it effects the signal. I can tell conclusively that the lnb is not seeing the whole dish... there are a few inches (maybe a palm width?)around the edge that he lnb does not see. I suppose this is what the feedhorn is for?

The motor seems to be holding tight. This thing must have some sort of closed loop servo or something because I feel 0 backlash when its on, and a small amount when it is off... it is a noticeable difference. My bracket is holding fine also .... I don't think the motor should have any problems in the short term.

My old J pole is not strong enough. it flexes too much. This is going to have to be replaced soon. I'm afraid that the inertial load from the pole flexing around might put extra stress on the motor and brackets. To make matters worse, I had to move the motor near the top so that the dish would clear the roof so this thing is a real wobble factory.

I have no real space in my yard for a ground based install... the roof is it. does anyone make an extra heavy duty roof mount? are there any popular ways to do this?

 

[guapoharry]

I'm kinda fond of these DirecTV slimline poles and supports.

They are much sturdier than the stock poles that came with my dishes. They don't bend or twist for me. However I don't know if they are sufficient for that heavy dish...