Reclaimed CM .75M - usable for ??

[RnR]

I was gifted a former DTN dish by a business recently and wonder to what degree it's usable for FTA. It is a Channel Master model .75M-1

I pursued it basically for audio services as I don't have a HD capable receiver, but am still curious as to what if any video services could be caught with it's limited size. I'm concerned that it's focus is a little too broad for the close satellite spacing these days...

And while I'm at it... any specific LNB or motor recommendations for it as well??

The CM was certainly weathered after ~20 years in service, but I couldn't let a molded dish sit all alone and forgotten any longer - if you know what I mean!

 

[osu1991]

Those are nice dishes and can get a lot of fta with them.

 

[RnR]

I'm hoping it's still useful for that... but would also like to hear some recommendations for outfitting it equipment wise...

For example, should I keep the feed or can I just toss it in favor of a standard LNB? A good motor for it, mount options, etc...

BTW... I'm in Michigan.

 

[Anole]

I'm not clear. Is this round or elliptical - (wide)?
If it's round, then any LNBf should be okay.
But, if it's elliptical, you are probably better off keeping the original feedhorn.
If it's got a dual polarity LNB, then that would be worth keeping.

Post us a picture - I'm sure it's something everybody will recognize, and we'll give ya better info. - :up

 

[RnR]

Can do on the pic... but the sun is on the wrong side of terra firma at the moment. Maybe tomorrow...

It's the standard offset Channel Master/Primestar oval/round design that has a slightly elongated vertical axis. But not elliptical in the Primestar 84E sense if that helps. It was originally a DTN - Data Transmission Network dish and had come with a flange mounted, fixed polarity NORSAT (unknown noise figure) LNB.

 

[Anole]

Okay, so three LNB support arms, then?
Sure, we know it well.
The path of least resistance is an LNBF of your choice,,,, but there are some dual polarity LNBs that can bolt up to your feedhorn.
There are pluses 'n minuses (mostly monetary) both ways.

 

[RnR]

Affirmative, (3) tubular support arms. And again this is the smaller 75cm edition of the familiar 1.2m.

So a flange mounted dual polarity LNB would allow for optimum reflector illumination using the original feedhorn... but a more common/cheaper LNBf would likely NOT illuminate properly - is this what you're inferring?

Any suggested brands for a flange mount edition?

 

[Anole]

So a flange mounted dual polarity LNB would allow for optimum reflector illumination using the original feedhorn... but a more common/cheaper LNBf would likely NOT illuminate properly - is this what you're inferring?

No, the round dish works fine with any off-the-shelf LNBF.
They have built-in round feedhorns.

Elliptical dishes work much better with the elliptical feedhorn that comes with the dish.

Any suggested brands for a flange mount edition?

I think this NJR LNB bolts right on. (get a second opinion)
However, there are also units on eBay, identified with the Hughes name that are similar.

Also, you can use the bandstacked Eagle Aspen LNB found on Global-CM's site.
(I can't find it on their site right now, but it has a tall elliptical feedhorn, which you remove)

Or, a surplus Dish Network FSS (bandstacked) LNB will do the job.

You might also find an old LNB off a Primestar, with two outputs: one Vertical, other Horizontal.

Double check the existing LNB. Post the complete part number. Maybe it's just fine.

 

[Tron]

Since that is a commercial molded Channel Master dish, it will probably outperform cheaper stamped metal dishes of the same size. As stated above, if you want both H and V polarities, you will want to remove the Norsat LNB and the small WR-75 waveguide that is attached to it. You will be left with the C-120 flanged feedhorn (round flange), to which you can mount many types of flanged LNBs. I recommend the Dish FSS stacked LNB from a Superdish (which is actually a re-branded Eagle Aspen P870)...

 

[pedrogarcia]

If you need multiple feeds then the Invacom LNBs have a c120 flange fitting.

 

[RnR]

I recommend the Dish FSS stacked LNB from a Superdish (which is actually a re-branded Eagle Aspen P870)...

Ok... but you lost me on the Superdish LNB... can you direct me to a picture of said item - or a commercial link? Sorry for my ignorance, but I'm not up on what a FSS stacked LNB - or a Superdish LNB in real life actually is.

And I should also mention that the plastic shield for the feedhorn throat came apart... I'm thinking I'll need to replace that before the snow flies... might any kind of plastic sheet be ok for that role?? (Sorry again to muddy the waters).

 

[RnR]

If you need multiple feeds then the Invacom LNBs have a c120 flange fitting.

True enough! I have looked at the Invacoms, but they are a tad pricey and I wonder if this "stacked FSS LNB" mentioned above might have an even better noise figure - although 0.3dB for the Invacoms looks kind of hard to beat.

 

[Anole]

SuperDish 101:

Ok... but you lost me on the Superdish LNB... can you direct me to a picture of said item - or a commercial link? Sorry for my ignorance, but I'm not up on what a FSS stacked LNB - or a Superdish LNB in real life actually is.

See post #8 above, there is a link to another thread discussing the hardware and pictures.
Basically, Dish Network used to have some SuperDish dishes deployed in the field.
They received 110° & 119° circular with appropriate LNBs, but also carried one linear LNB for use on 105° or 121°.
Yes, they had several models, depending on what part of the country the user lived in.
Those satellites are no longer in use by Dish Network, and the SuperDishes are now obsolete.
So, in the normal course of replacement, many SuperDishes and parts become surplus.
The FSS LNBs from these dishes are popular with a small segment of the FTA users, and available from cheap to free.

These are bandstacked LNBs, where both vertical and horizontal signals are available on a single coax without any sort of switching.
A search on the forum will pull up more info and pictures, but hopefully this will be sufficient to help you decide if you are interested in going down this path.

The flanged Invacom LNB are probably a bit better, but as you have observed, quite expensive.


Iceberg on Bandstacked Dish Network LNB frequency considerations:
http://www.satelliteguys.us/free-air-fta-discussion/117442-surplus-super-dish.html
- which LNB to use on SuperDish:
http://www.satelliteguys.us/free-air-fta-discussion/159383-amc-21-superdish.html

 

[RnR]

AS promised, here is a pic of the dish (cleaned up a tad). Initially, I had pulled the feed cover off while it was sitting in the living room... and discovered a massive hornet hotel and a bunch of startled tenants! I got that thing outside PRONTO!!



Anyway, the LNB model number is: BSCC83N01, no noise figure rating and I think it's single polarity though I haven't pulled it off the ring yet. And after looking at the 'Bay, I have not seen any FSS LNB's from Dish, but a couple from Hughes did pop up - one that looked like a can with one connector and another that was a flat looking thing with two outputs. Both appeared to expect flange mounting. Presumably those would work as well if I didn't want to spring for an Invacom.

 

[pedrogarcia]

I wonder if this "stacked FSS LNB" mentioned above might have an even better noise figure - although 0.3dB for the Invacoms looks kind of hard to beat.

Yes they sure are pricey but the noise figures are correct unlike some LNBf manufacturers claims these days. The advantage is the multiple feeds.

The disadvantage of the C120 feed horn is that it is open to insect invasion and I think I'd go for a cheap 30 mm LNBF. I know Inverto make 30mm universal LNBFs not sure about standard

 

[RnR]

After some rummaging around, I came up with an SNH-031 I had targeted for a larger dish a good while back, but I think it would be better utilized on this 75cm where there is less signal available.

I guess I was thinking I had to use the dish's original feedhorn and hence needed to pursue a C-120 compatible for optimum results. But if the SNH-031 can see the whole surface and none of my weedy lawn, then...

... I think I'm golden : despite the single output.

Do you guys agree with this assessment?

 

[Anole]

yes:

I was wondering if you were getting sidetracked, trying to put a $100 LNB on a slightly-smaller-than-ideal dish.
Your SNH-031 should be fine.
And if you want Universal or Standard, the little GeoSat Mini LNBs are fine, too.
Even come in dual output , if you want to expand to more receivers.
Another regular sized option might be the blue DMX521.

I don't have one of those dishes, but I seem to recall some talk about mounting regular LNBs where the small feedhorn neck of the original LNB was located.
I'm thinking Iceberg suggested taking the plastic housing off a GeoSat Mini, but you'll have to find the thread to see if it was a serious situation or just a convenience.

 

[RnR]

As it is, the black feedhorn clamp handles the 40mm O.D. of the SNH-031 perfectly. Of course I can't utilize the molded in recesses that are there for the original hardware, but there's no wobble. I'll have to play with the exact positioning of it though as it can slide forward and back a tad in a loosened clamp for peaking.

At least this way I can get started ... that is once I find a decent post, which may present it's own problems too.

 

[Anole]

post:

Around $15 or maybe $6..8, at Home Depot - depends on diameter and length.
Look in the fence post aisle, and the conduit aisle.
Just don't have it too tall, and it'll be fine.

I had one out by my garage a while back. Think it was $16 or so.
Somehow it -disappeared- :rant:

 

[Tron]

When I first got my 1 meter Channel Master (basically larger version of the same dish), it had no LNB whatsoever. I used a Fortec FSKUV universal LNBF in the LNB holder for some time. It worked well, but then I found a feedhorn and Norsat LNB assembly that was made for that dish. I removed the single polarity Norsat LNB and waveguide from the feedhorn, and replaced that with a Dish FSS stacked LNB. It works wonderfully aimed at 125w for PBS.