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Thread: dmx 741 question
- 10-25-2009 04:57 PM #1
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well i went out and tried to lock in 97w for the first time. i am using 39" dish from wsi and dmx 741 lnb with the c/ku connected. i have the coolsat 6000. i couldnt get any signal. (probably the trees here in Maine) but i'm moving to the roof this week. what i wasn't sure was i had the dmx set at vertical and not horizontal in the coolsat menu. i had the lnb on, switch turned on, and tried 10750 and 10600 for lnb setting for 97w. my lat and long location is 44.5758 and -68.7745. i used a compass for mag azim of 234.4 and lnb skew of 25.6 which i tries clockwise and counter clockwise. oh and elev was set at 31.5. any help with the h or v setting and anything i should try from info above i would really appreciate it.
- 10-25-2009 04:57 PM # ADS
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- 10-25-2009 09:32 PM #2
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Can anyone help me with this?
- 10-25-2009 11:00 PM #3
Given your coordinates, I can confirm your magnetic azimuth, elevation, and skew.
Skew will mean twisting the LNBF 25° clockwise, if you are standing BEHIND your dish (or the other way if you are in front of your dish, on the LNB side).
See below for how how to set up several common dual-band LNBFs for zero skew.
LO on the "u" model is 10600, but if you have the DMX741 without the "u", then it's 10750.
A picture showing how you mounted your LNBF would be helpful.
However, in many cases, the large diameter feedhorn will be centered a bit above where the Ku LNBF would normally be located.
This tends to inject a bit of vertical offset, so you should compensate by aiming the dish a bit ... higher !
Of course, the focal length may be somewhat off from what you are expecting, so give that a try.
In fact, if this is your first shot with the new LNBF, you might try a really hot bird, just to get started.
Maybe one of the pay satellites, and use a $10 sat meter.
It'll respond to the high powered DBS signals (or at least I've found that to be so).
edit:
Oh, one last thought. The DMX741 has a switch, and it's different in the "u" model.
Take that out of the equation for initial tests.
Anole pix of skew for CK-1 and BSC-621 LNBf's
http://www.satelliteguys.us/1281374-post50.html
[09:19] <Anole> Fred - how do you orient the DMX741 at TS ?
[09:19] <Linuxman> you can put the 0 line at either north or south
[09:20] <Linuxman> it has a plus or minus 10 degrees off center if i remember correctly
Iceberg and skew of C2:
http://www.satelliteguys.us/free-air...ml#post1939026
- 10-26-2009 05:29 PM #4
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pics of the problem, I think
thanks Anole for the information. i tried what i could today. i moved the location but i included pics of the l.o.s.. i was trying to get it to work on the ground without going to the roof. i took the little tv and receiver out to try to dial in 97w and no luck. i tilted the dish up and down. moved it back and forth from my mag declination. turned the lnb counterclockwise in front of the dish. each time itried on thing or another when putting the rest at the exact specs and couldnt lock anything. the pole was plumb when i mounted it and when the dish was on it. are the trees just to high even if i take it on the roof??? oh and i tried it just with ku and not combined on one try then jumpered on the second.
- 10-26-2009 07:12 PM #5
You are working with a lot of unknowns all at one time.
Can you put on a stock Ku LNB and get something?
Is this the first time you've played with a Coolsat 6000?
Is this your first experience with that dish or this location?
Hard to tell from the pix, but your LOS looks terrible.
You need something easy to give you a foundation to start from.
If that means aiming an old DirecTV dish at 101°, 110°, or 119° circular, just to see it light up, then maybe that'd be a good step.
- 10-26-2009 07:27 PM #6
Outbackjack
I would recommend that you do not use that particular LNB until you get more experience in satellite alignment. I can tell you that it is very hard to adjust the KU portion of that LNB and the C-band is also hard to align for that size dish.
I gave up trying to use that LNB to do C-band & KU together, matter of fact I have unscrewed the KU portion of the LNB and use it separately.
I would suggest you use a KU Standard or Universal LNB only to start out with. Also I mount the LNB holder into metal rod. (see picture)
Here is picture of my setup for C-band, I’m pointing at 72W and just about get a c-band signal off of that satellite. I use a KU Invacom Universal LNB on my set up check out the pictures below.
Don’t get discouraged it takes time to get your first dish set up. It took me 5 full days working at it. You can get alot of help and advice from this site.
Good Luck
Mikelib
- 10-27-2009 04:41 PM #7
Hi Jack I agree with Mike a 100%
I also have the DMX741U & found is very difficult to get both C & Ku. You can pick up a good LNBF pretty cheap & get a lot of free TV with it.
I just bought a this one,
Chaparral Heavy Duty Universal LNB
and I am excited to get it. I would recommend a standard LNBF for your first instead of a universal
I think once you get the dish up & running you can play with the C band & see what you get, but honestly 39 inches is too small for C. You really need to start with a 6 footer & then HD can get choppy
- 10-27-2009 06:15 PM #8
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Thanks for all the help Anole, mikelib and Auric. yes Anole it is the first time for this dish. i was the one that got the patriot dish for a buck but after almost breaking my back (and the cinder block i was standing on) trying to assemble it i went with the 39" dish. i will use the ku that came with the patriot and see what i can get. i put up a couple pizza dishes before but i know that ku is a lot harder to get than direc. my old direc dish is at the corner of my house on the roof. thats prob where this one will have to go before the snow starts. thanks again guys for all the help. i will let you know how it goes.
- 10-27-2009 07:17 PM #9
- 10-29-2009 12:51 PM #10
SatelliteGuys Regular
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I tried using my DMX741U with my 39 in dish and could not get anything on Ku/C. This lnb is designed primarily for prime focus dish. If you are using it on a smaller 39in dish it might work however after extensive reading on the forums you would need a scaler ring or make adjustment on the satellite arm (lenghten it) because it is an offset dish and the focus would be off.
Better buying a cheap Ku lnb for less than $10. I did that and get all signals in the 90% with my 39in dish on Galaxy 19 (97 W).
Incidentally I thought my DMX741U was defective, until I used it on my 6 ft Polar Mount Dish. Excellent performance in C/KU Linear & Circular, especially for the price.

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