BSC621 BSC-621-2 C / KU Band LNBF

satcom1 · Aug 23, 2008

Broke this away from my thread on Primestar 84E BSC-621-2.

In my opinion and from experimentation I'm shelving the BSC 621-2 because this LNBF has too many trade offs in performance. A seperate quality C-Band LNBF and KU Band LNBF will work much better.

On a dish smaller then 6' in diameter;

My findings are that at best C-Band performance is almost useless and KU Band is even worse and this is with two distance focal depths. A compromise between the two settings is even worse.

Maybe on a Prime Focus BUD this LNBF would be OK, but probably not as good as seperate LNBF's

Just my opinions folks. a grain of salt.

Anole · Aug 23, 2008

Since you seemed more inclined to the separate LNBs for each band, here is a little more polished solution.
While this is an overpriced commercial offering, it wouldn't be difficult to drill a big hole in the scalar and stick a Ku-band LNB through.

Of course, the reference links you provided in your other thread, which went back to 2005 with this 84e dish idea, didn't really work out all that well either.

The guys using 1.2 meter dishes (4 foot) seem a happier lot.
Bloomdog, PopcornNmore, and QWERT1515 all have 1.2 m dishes on C-band.
You might search for postings by them and notice that the C-band LNB is offset on most or all.

satcom1 · Aug 23, 2008

The whole point here is to use the smallest dish and get the most

Anole said:
Since you seemed more inclined to the separate LNBs for each band, here is a little more polished solution.
While this is an overpriced commercial offering, it wouldn't be difficult to drill a big hole in the scalar and stick a Ku-band LNB through.

Of course, the reference links you provided in your other thread, which went back to 2005 with this 84e dish idea, didn't really work out all that well either.

The guys using 1.2 meter dishes (4 foot) seem a happier lot.
Bloomdog, PopcornNmore, and QWERT1515 all have 1.2 m dishes on C-band.
You might search for postings by them and notice that the C-band LNB is offset on most or all.

The whole point is to use the smallest dish possible and get the most channels possible.

Otherwise I just switch over to my 10' BUD.

Alot of people can't have larger then 1 meter dishes and this experiment is for that need.

1.2 meters is definetly not appropriate.

If DREAMFOX gets the performance he has stated then that is more then enough for alot of folks, that otherwise could not have C-Band.

Your scalar photo is perfect for the next project, but I will center the P* elliptical scalar ring between two overlapping C-Band scalar rings I will use the second Panarama for circular. QPH-031 with C120 interface to the P* elliptical circular scalar ring.

Don't you ever sleep?

Machman · Aug 23, 2008

I would have thought that the BSC621-2 would work better for simultaneous C/Ku on a small dish, since I've read many times that a Ku LNBF on a large BUD has to be positioned much more precisely than one on a DBS dish, for instance. Maybe my mistake was assuming that this thing would work as advertised under any circumstance.

I was planning to get C and Ku from one particular orbital slot on a fixed dish. I guess I'll have to go with separate C and Ku LNBFs and motorize the thing. Now I just need to find a reasonably priced (<$60) C-band LNBF that has a high performance/price ratio. Does anyone know if the 13K Panorama or BSC-421 outperforms the BSC-621?

Mr Tony · Aug 23, 2008

I have a 421 and a 621 and they work about the same on C-Band

I have the 621 on my 6 footer that I ghetto move but its for C-Band only. I dont bother with KU because I lose hair trying to work with it

Anole · Aug 24, 2008

Machman said:
Does anyone know if the 13K Panorama or BSC-421 outperforms the BSC-621?

There doesn't seem to be anything in print that suggests any of them are significantly better than others.

Couple more you might consider:
- Eagle Aspen bandstacked C-band LNB at Sadoun. With or without scalar. Good if you want to feed several receivers.
- SatelliteAV and his CK-1. Described in several Linuxman threads.

satcom1 · Aug 24, 2008

Good Information

Anole said:
There doesn't seem to be anything in print that suggests any of them are significantly better than others.

Couple more you might consider:
- Eagle Aspen bandstacked C-band LNB at Sadoun. With or without scalar. Good if you want to feed several receivers.
- SatelliteAV and his CK-1. Described in several Linuxman threads.

Anole,

Last Tuesday I ordered the B1 Stack from Sadoun and will test it. So much for USPS 3 day shipping.

Today, I ordered the Panorama LNBF that DREAMFOX1 uses and will compare it to others.

I was so glad to see Linuxman start his project with the true 1 meter P* dish, we then can compare results between P* 1m/E and 1m/offset. My gut feeling is that his results should compare to DREAMFOX1.

The B1 stack is rated at 65 db gain and 17 degrees vs the Panorama at 55 db and 13 degrees. Should be iteresting.

satcom1 · Aug 24, 2008

Summary

To be fair to the BSC-621 and the CK-1 I will say that they were most likely designed for a large C-Band dish, Because of the large number of wavelengths between the dish surface and the feedhorn coupling, phase error and impedance matching is much better. The Wavguide and other design elements of the C-Band throat are likely designed to couple energy better to the KU Scalar Ring deep in the throat of the dual LNBF on a large dish. As compromise is always part of an engineers design, I would say that these dual LNBF's will work best on a 10' diameter C-Band dish.

Attempting to get the BSC-621-2 to work on a close coupled dish smaller then 6' in diameter is not going to give satifactory results. But that is not the fault of the LNBF.

So in my opinion; this type of LNBF should be considered for a large C-Band dish when some KU Band channels are desired.

lumpkin666 · Aug 25, 2008

satcom1 said:
... I would say that these dual LNBF's will work best on a 10' diameter C-Band dish....

I feel sorry for you guys trying them on smaller dishes then, because on my 10' dish they seemed pretty worthless

satcom1 · Aug 25, 2008

BSC-621-2 KU LNBF Comparison

The BSC-621-2 KU LNBF section was mounted on a Winegard 76 cm Offset dish and tested against a SNH-031 Invacon LNBF.

The SNH-031 gave a SQ of 57
The BSC-621-2 KU LNBF gave a SQ of 49.

cracklincrotch · Aug 26, 2008

satcom1 said:
The SNH-031 gave a SQ of 57
The BSC-621-2 KU LNBF gave a SQ of 49.

So the SNH-031 is 16% higher than the BSC-621-2. That's significant to me. That's often the difference between a lock and breakup during rain.

satcom1 · Aug 27, 2008

Test results

When I took the BSC-621-2 apart for testing of the KU Band LNBF, I made a cutoff plate for the back of the C-Band LNBF. I wanted to see if the C-Band section could be used by itself. This would determine what performance it has stand alone.

It cannot be used alone. The KU Band section helps to form a C-Band resonant cavity at the back of the LNBF.

satcom1 · Aug 27, 2008

Received the B1 Stack from Sadoun today, one week after I ordered it.
Tested it against the BSC-621-2 C-Band LNBF.

The BSC-621-2 read a solid 41% SQ and had a broad adjustmant range.
The B1 Stack read 37% SQ and has very sharp tunning range.
I will be receiving the Panorama 13 degree K LNBF late this week and will post results here.

PopcornNMore · Aug 27, 2008

Like I mentioned before C band received on my Channel Master 1.2m dish is very good. In fact, as good or better than the C band received on my Fortec 1.8m dish.

After reading about the 7-10dB loss when using the SG2100 motor drive I am going to try bypassing the motor using a high frequency switch and see if the C band is improved even more. I will post my results so you can compare signal strengths on various transponders and satellites.

satcom1 · Aug 27, 2008

I will post my results so you can compare signal strengths on various transponders and satellites

That will be very interesting to me.

I am looking forward to seeing how Linuxmans' experiment goes.

cracklincrotch · Aug 28, 2008

You're not the only one hoping for good results from this. Just waiting myself here to see how it goes before I drop some $$$ on this myself.

Feels like Christmas!

Anole · Aug 28, 2008

Satcom -

Remove the back cover plate off the B1 and take a peek.
Kinda funny looking back there.
Just a little recess, and a hole through to the C-band probes.

I joked in another thread about shoving a stripped-down GeoSatPro MINI in there.
... and maybe even fine tuning it for both skew and insertion depth (read: focus point!)

At the very least, maybe you can see some reason to do some sort of tuning back there to improve C-band performance...?

Don't mean to distract you from your C-band quest. Just some observations.

Anole · Aug 28, 2008

PopcornNMore said:
After reading about the 7-10dB loss when using the SG2100 motor drive I am going to try bypassing the motor using a high frequency switch and see if the C band is improved even more.

So far, I haven't seen comprehensive proof that all motors are so badly built.
It is certainly possible to use a 35¢ choke in the design instead of a printed circuit inductor.
Maybe other brands or earlier models of the 2100 do a better job.

But, as always, do check and let us know! - :up

edit: removed reference to C-band frequencies. All LNBs put out the same range of frequencies.

satcom1 · Aug 28, 2008

Anole-

You are entitled to your "opinoins" I'll stick by "proof of Performance"

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