Dual Polarity for Muzak dish / flange?

[RnR]

I picked up one of those white Muzak dishes as referred to in this thread...

http://www.satelliteguys.us/free-air-fta-discussion/164553-new-dish-muzak.html

and am having a problem coming up with a good solution for converting the specialized feed to dual polarity. Preferably, I want to maintain usage of this particular feed horn as we're talking elliptical here.

Like a lot of these commercial dishes, the feeds are designed for use with block style single polarity LNB's with a polarity reducer. This 1m x .76m dish looks a lot like an updated Primestar, but unfortunately the LNB mounting flange used on the feed is NOT directly C120 compatible.

I've attached a couple of pics to illustrate. Notice the (6) hole pattern used on it's flange coupler; totally different from the (8) hole pattern used on the C120 (a Dish FSS LNB is shown for comparison).

Thus my question is... has anyone successfully mated a dual-polarity LNB to this style of feed horn??

Failing an elegant solution, I might have to come up with some way to clamp the Muzak feed collar to the Dish FSS, but don't know what problems that may entail. And I suppose if I get real ambitious, I might just drill (4) new holes in the FSS LNB flange using the Muzak collar as a guide and screw 'em together - but even then, I'm left with a cheesy mating right at the feed throat as evidenced by the FSS O-ring not mating up very well with a flat metal surface for environmental sealing. It sure would be nice if a proper mating adapter to a C120 were out there somewhere!

Has anyone previously conquered this conundrum?

 

[RnR]

Come on guys, put your thinkin' caps on!

 

[cruzin]

I have not converted any like you want to do but I have swapped them from feedhorn to feedhorn. I had one went bad on my 1.0m true focus which had a longer wave guide than all my others and removed a good lnb from a shorter waveguide and put it on it I have found some with different bolt patterns and did not mate properly. It is probably a dooable what you want to do.

Come on guys, put your thinkin' caps on!

 

[Larobpra]

Take the four screws out of the adapter on the Zinwell LNB and use the 4 holes to mate up to the 8 hole LNB. Should do the trick. You will probably find 8 holes in the Zinwell too.

 

[RnR]

That would be feasible if the hole patterns were built on the same dimensions... but alas, they are not. And as such, they do not match up by several mm.

Nice thought however!

 

[guapoharry]

Have you tried rotating the adapter on the Zinwell? Perhaps by 90 degrees?

Maybe some of the holes will line up better with a different orientation.

 

[emuman100]

I got a 92cm Prodelin Rx only dish and it came with the Zinwell LNB. You can remove the Zinwell LNB and use one that Invacom sells and connect it right to the feedhorn.

 

[cruzin]

you may be able to save money by just buying a 36 or 39 inch dish with lnb.
Ive also seen the invocom lnb sold that bolts up to a clamp and also you can buy the feedhorn for it. I have the other type muzak dishes with the 3 arms that come out and a clamp that holds a lnb. I was able to modify it for other types of lnbs.

I picked up one of those white Muzak dishes as referred to in this thread...

http://www.satelliteguys.us/free-air-fta-discussion/164553-new-dish-muzak.html

and am having a problem coming up with a good solution for converting the specialized feed to dual polarity. Preferably, I want to maintain usage of this particular feed horn as we're talking elliptical here.

Like a lot of these commercial dishes, the feeds are designed for use with block style single polarity LNB's with a polarity reducer. This 1m x .76m dish looks a lot like an updated Primestar, but unfortunately the LNB mounting flange used on the feed is NOT directly C120 compatible.

I've attached a couple of pics to illustrate. Notice the (6) hole pattern used on it's flange coupler; totally different from the (8) hole pattern used on the C120 (a Dish FSS LNB is shown for comparison).

Thus my question is... has anyone successfully mated a dual-polarity LNB to this style of feed horn??

Failing an elegant solution, I might have to come up with some way to clamp the Muzak feed collar to the Dish FSS, but don't know what problems that may entail. And I suppose if I get real ambitious, I might just drill (4) new holes in the FSS LNB flange using the Muzak collar as a guide and screw 'em together - but even then, I'm left with a cheesy mating right at the feed throat as evidenced by the FSS O-ring not mating up very well with a flat metal surface for environmental sealing. It sure would be nice if a proper mating adapter to a C120 were out there somewhere!

Has anyone previously conquered this conundrum?

 

[Bill_KY]

I picked up one of those white Muzak dishes

Are these available on E-bay? How much do they cost?

 

[RnR]

Gettin' close...

What I've found is that the adapter/polarizer and it's hole pattern can be mated to the C120 flange - provided orientation is correct. If it doesn't match, try the 90-degree rotation trick and you'll get a (4) hole match up. That's a decent mechanical solution for any C120 LNB and since the original polarizer is still in play, the feedhorn assembly is also retained 100% - just what the doctor ordered for the elliptical dish!

But one problem remains... the polarizer still polarizes.

So, what I'm going to try next is a temporary NPM on the dish in the yard with this arrangement looking at (maybe) 97w and see what does and doesn't work with the dual polarity LNB and a polarizer downstream of the feed. (In time, perhaps I can have the polarizer bored out to the proper throat dimension, yielding a non-polarizing polarizer! )

I've pre-skewed the LNB by 14 degrees or so which is what is supposedly needed for my neck of the woods if I were to target 97w.

Ya know... why don't the installers EVER skew their commercial dishes?? I've looked at several of these installs and they are oriented perfectly vertical no matter what bird they're looking at. Dish and Direct have to because of multiple birds scattered across the arc - but these single bird dishes like to stand tall and pretty, I guess. They must lose some efficiency along the way doing that...

 

[RnR]

Are these available on E-bay? How much do they cost?

I don't think so... I got mine from an old commercial installation and had remove it off the building's roof.

 

[RnR]

Take the four screws out of the adapter on the Zinwell LNB and use the 4 holes to mate up to the 8 hole LNB. Should do the trick. You will probably find 8 holes in the Zinwell too.

Only (4) holes in the Zinwell... but otherwise you're on track (see my prior post).

 

[Larobpra]

I thought it might work.

 

[RnR]

...I have the other type muzak dishes with the 3 arms that come out and a clamp that holds a lnb. I was able to modify it for other types of lnbs.

That looks just like a Prodelin 1.2m I have. I would be most grateful if you would post a closeup pic or two of how you modified the original feed bracket to host the 40mm dia. LNB that was (teasingly) shown!

 

[cruzin]

That looks just like a Prodelin 1.2m I have. I would be most grateful if you would post a closeup pic or two of how you modified the original feed bracket to host the 40mm dia. LNB that was (teasingly) shown!

I think at that time I just used some straping with holes in it and put bolts through the holes in the strap and through the holes in the original holders bottom. I do not use that lnb any longer and have since went to this setup with 2 lnbs for 97 and 101.

 

[Tron]

Ya know... why don't the installers EVER skew their commercial dishes?? I've looked at several of these installs and they are oriented perfectly vertical no matter what bird they're looking at. Dish and Direct have to because of multiple birds scattered across the arc - but these single bird dishes like to stand tall and pretty, I guess. They must lose some efficiency along the way doing that...

The dish itself may not be skewable (usually the elliptical ones are), but if the dish isn't skewed, the LNB certainly must be if the dish is aimed at a satellite that isn't near true south.

 

[RnR]

Well, here we are!

97w is stable and active on the dish (which I guess is actually classified as an 84cm) - both polarities.

Getting started, SatMex6 was the first satellite I discovered with my cheapo sat finder and a bit later, I headed back east and ended up one slot past 97.0w, then finally settled in on G19 when I got around to doing blind scans on a decent receiver. My old favorite... a Coship 3188c, is presently suffering from leaky power supply capacitors and is out of commission for the moment. But a born again Coolsat 5000 did just fine as a stand-in and will be relied upon over the next day or two as I see just what effect the rectangular opening in that WR75 "transition" collar (aka. polarizer) has on signals of both H & V polarities.

So... for now the peaking remains to be performed but I'm happy that the mechanics of the feed coupler didn't throw too big of a monkey wrench in the works. :up:up

 

[cruzin]

congrats!