Is Ku band on the DMX-741 better than on the BSC-621?

[transco]

I'm getting excellent C-band performance from my BSC-621 (Pansat 3500SD+ and 3M Orbitron mesh), but the Ku band is terrible. For example, on the C-band side of SatMex-6 I'm getting SQ readings in the 95% to 98% range, but I'm lucky to get 10% on the Ku side. I've spent hours tweaking the f/d setting and polarity. Feed horn is dead center, and dish symetry is nearly perfect, but still lousy Ku performance. Anyone replaced a BSC-621 with a DMX-741 and see significantly better Ku signals?

 

[Skyscanner]

Trans,
Overtightening the BSC621 KU can cause it to move internally, throwing your skew off. Try loosening the jam nut with the coax still connected, and if it's possible to have a receiver and monitor on site, watch the Q while you rotate the threaded portion [use the fitting [coax] nut]. When you get max Q, carefully tighten the jam nut, being careful not to let it move internally inside. Used to have the same trouble, but now have 79-83 Q on KU band and 84 Q on C band on 101W and a Coolsat 6100 rx. Others have improved their results by adding a spacer between the C and KU bugle, but I haven't found that to be helpful.
Sky

 

[Lak7]

Which Ku TP are you trying for, and where are you located?

 

[transco]

Which Ku TP are you trying for, and where are you located?

I'm in the SF Bay Area and have been working mainly with SatMex-6 and G-19. Please note, it's not a 'footprint' problem. I have a little motorized DirecPC dish that pulls in the Ku channels perfectly, as did the 3M dish with the original C/Ku band Corotor-2 feedhorn.

I just tried Skyscanner's fix. The SQ may have increased a percent or two, but not much.

 

[Anole]

From reading the forums, I've gathered the 621 has had a bad reputation on Ku.
However, very careful installers have been able to get quite good Ku on the SatAV CK-1, and the WSI DMX741.
I often wondered if maybe more dedicated installers proved the later LNBFs -could- be tweaked?
But, I've never seen anyone who got the later units running, go back and try with the 621.

This looks like it might be a clever technique to try:

Is this a temp mount,is it level or plum,are you sure the lnb is facing dead center on the dish.?
To get mine dead center I used two strings 1 north to south,the other east to west across the front of the dish.
Then I removed the lnb cap and looked from the back of the dish from the hole in the center.
And Made the cross hairs center on the lnb.
(inside the lnb their is a metal bar,this bar should face East to West when on your true south,so skew would be 0.)

 

[comfrey]

For a quick check, remove the plastic cover on the feed horn throat. (pry it off with something like a knife)
Take a look down the feed horn to where the Ku section is (right at the end), look for 2 little probes sticking out of the sides, make sure they are not bent and line up in a proper X Y fashion.

I'm in the SF Bay Area and have been working mainly with SatMex-6 and G-19. Please note, it's not a 'footprint' problem. I have a little motorized DirecPC dish that pulls in the Ku channels perfectly, as did the 3M dish with the original C/Ku band Corotor-2 feedhorn.

I just tried Skyscanner's fix. The SQ may have increased a percent or two, but not much.

 

[transco]

Anyone have a picture looking down the throat of a working BSC-621? I'd like to compare it to mine and make sure everything is where it's supposed to be. For example the orientation of the Ku-band probes relative to the C-band probes relative to the support bar.

 

[Anole]

I had links to the DMSI web site with those pictures, but they moved 'em.
Try here -
621 manual was relocated: http://www.dmsiusa.com/docs/621-manual.pdf

 

[Skyscanner]

Trans,
Are you using the internal 22KHZ to switch bands? If you are, try a separate coax for KU just to eliminate the possibility of a possible switch problem, and if you are using the internal switch, do you have "22KHZ swith on" enabled for KU? Just a thought.
Sky