1.8m KU-Band RX-TX Antenna & DMS BSC621-2D LNBF

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roguepayne

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Jan 6, 2007
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I was wondering if a DMS BSC621-2D LNBF would work with a 1.8m KU-Band RX-TX Antenna? Thanks in advance.
 
Here you go Iceberg....thanks again
channelmaster.jpg
 
That looks like an offset dish. If that is the case, then the c/ku units may not work./ If you want to get C-Band on it, then it should work with the 621. But the KU part isnt the best on a Primes focus dish normally. Throw in the fact you have an offset dish and KU....well.....stinks

I tried the Geosat C/K1 on my 4 foot offset and the numbers were not that good versus a regular KU LNB
 
If you insist on using that 6' offset dish . . .
- use a DMX741 or Ck-1 LNBF
- get a conical scalar, which should help with C-band
- be sure to carefully locate and tune the LNBF on Ku band.
That'll get the most out of what you got.
Will it suit you or be the best? Well, try it and let us know. :)

A six foot dish is probably a reasonable low-end size for C-band.
How will it work on Ku?
As Iceberg pointed out, it'll be less than the same dish with a dedicated Ku LNB.
However, such a large dish may compensate for the reduced Ku performance of the LNBF.

We've got members with spun-aluminum 8½ foot dishes, using Ck-1's and DMX741's, getting outstanding Ku.
It took 'em painful effort in tuning and alignment, so your mileage may vary.

And, the most important question: what do you expect to receive??
 
Anole
The folks using the combo units are prime focus dishes. I have a feeling the offset part will totally kill KU.
 
good point, but:

The dual-band LNBF's have a F/D on Ku more like .6 or .7, instead of the .3 to .4 they have on C-band.
So, in theory, that might be a better fit for the offset dishes.
But presumably, they'd still be a bear to get located, focused, and aligned... just like on a prime focus dish.

And of course, the flat or conical scalars are only effective on the C-band signals.
No consequence to Ku.
The Ku LNB has a scalar (or scalar-function) built into the back of the feedhorn.

Well, that's my theory, and I'm stickin' to it! - :cool:
 
I had a DMX741 with the conical scalar on a 1.8m prodelin offset dish for about 6 months. It worked OK on C band but was poor on some transponders because of adjacent interference (as expected). It outperformed my 36" offset with an Invacom QPH 031 LNB on many Ku transponders but it was very tricky to align and still had some transponders where the 36" was better on ku.

I have recently moved the DMX741 over to a 10' prime focus dish and the invacom over to the 1.8 offset and put a DMX521 on the 36" offset and all I can say is WOW.

The improvement of the Ku signals with the Invacom qph031 on the 1.8m over the DMX741 was real noticeable. The DMX741 on the 10' C band over it being installed on the 1.8m offset was also a big gain. The 10' dish with the DMX741 doesn’t quite work as well on ku as the QHP031 on the 1.8m offset but its real close.

I guess it just shows that putting the right stuff on the right dish pays off but I was just working with what I had at the time.:)

Bottom line is that a DMX741 can work OK for C and ku on a 1.8m offset dish but don't expect to dig out the DVB-S2 and weak signals on either band with it.

If I were to put a number to it I would say I get about 30% more signals on C and 10% more Ku now than I did with the 1.8m offset / DMX741 combo alone.
 
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