Thread: BSC321SP F/D ratio

OK just wanted to make sure it was the right channel

Iceberg,

11874 H TP 8, 304, 869, 870 TH. This is from Lyngsat. Iceberg, could you explain what these numbers mean as I never quite got what all those numbers represent.

Thanks!

Eric

OK just got done with the testing and the results you might like

Tried 3 different LNB's
-Geosatpro SL1P Prime Focus .6 KU LNB
-Sadoun dual Universal .4 LNB used for offset dishes
-GeoSatPro C/K1 C/KU Band LNB for Prime Focus dishes .4 KU side

Hooked up the SL1P and got 97W dialed in. Peaked for optimum quality and blind scanned. Took results from various transponders including the one you want (11871 for DMC)

Got done and unhooked LNB and put a Sadoun dual Universal LNB in its place. Since this is designed for offset dishes I figured the quality would go down.

Last was the GeoSatPro C/K1 which is both C-Band and KU Band.

All were on the Fortec 6 foot dish and Pansat 1500 which has a "true" (and spazzy) meter. normal rule of thumb is 30 quality would be threshold. I'm in Minneapolis, MN

SL1P results
quality/transponder/channel
90 11871 DMC
99 11777 PIT
95 11966 WORD
90 12055 AFRICA TV
99 12122 ALJAZEERA ENGLISH
91 11833 DAYSTAR
80 12050 PRESS TV
88 12115 PASTOR SCOTT
75 12177 TELECULTURE
99 12152 RUSSIA TODAY
One thing I noticed is the quality was rock solid. Normally the Pansat would jump like 60/75/68/74/63 etc....the only one that jumped was Word which would jump between 92 & 99 all the time

Results with the Sadoun dual
quality/transponder/channel
74 11871 DMC
99 11777 PIT
83 11966 WORD
75 12055 AFRICA TV
90 12122 ALJAZEERA ENGLISH
76 11833 DAYSTAR
74 12050 PRESS TV
66 12115 PASTOR SCOTT
60 12177 TELECULTURE
90 12152 RUSSIA TODAY
Some transponders only dropped a smidge but some dropped like a rock. Also the meter was back to its spazzy self. I took the "Common" number of quality. Doc Scott was at 66 but would spike to 72-73 then right back to 66-67 for 3 or 4 seconds.

The C/K1 had some really wacky results. Maybe it wasnt skewed 100% correctly but meter very spazmastic

quality/transponder/channel
60 11871 DMC
90 11777 PIT
45 11966 WORD
75 12055 AFRICA TV
90 12122 ALJAZEERA ENGLISH
90 11833 DAYSTAR
60 12050 PRESS TV
72 12115 PASTOR SCOTT
74 12177 TELECULTURE
50 12152 RUSSIA TODAY

some pics of the LNB's and specs of the LNB's and a screengrab of DMC with the Prime Focus LNB

I noticed the Prime Focus LNB the meter was rock solid. That 90 on DMC never went below 89 and maxed at 96/97. SO you should be good. It was pushed all the way back in the holder away from the dish. I did get the LNB pushed in about 1/2" towards the LNB and the quality stayed the same. If I pushed it all the way in then the quality went kaput (down to 45 or so)

Originally Posted by jags1

Iceberg,

11874 H TP 8, 304, 869, 870 TH. This is from Lyngsat. Iceberg, could you explain what these numbers mean as I never quite got what all those numbers represent.

Thanks!

Eric

11874 is the transponder frequency
H is polarity
TP8 dont need to worry about. That is what transponder it is on the satellite
Globecast TV which is the subscription part has their own receiver that they use. Lots of channels are free (DMC Is one of them) but they do have some subscription channels...304 is what channel number it shows on those receivers
869 & 870 are the audio & video pids...all consumer receivers find these when you scan the transponder. It separates the channels on the transponder
TH is the language (E for English, SP for Spanish, FA for Farsi, etc)

IN my post above, I locked DMC on 11871 which is 3 off but thats fine. Each LNB can read the frequency off by a couple

WOW!!! Thanks so much Iceberg!!!

Those numbers are really great!! With the setup I have in Los Angeles on a 3 foot dish I'm lucky to get 30% on the DMC channel. It would often drop out. I did figure out that I could fine tune the reciever by adjusting the transponder frequency to get the best reading. I read somewhere that the set frequency in the LNBF starts to drift as the LNBF gets older. So to get the best signal you have to compensate by readjusting the frequency in the reciever. Is this correct?

Also it looks like that Geosatpro SL1P Prime Focus .6 KU LNB works the best, eventhough it has a F/D of .6. Must have something to do with the physical construction of the scaler rings in the front of that LNBF. Must be somehow different than an offset LNBF. Maybe the electronics are the same as what is found in an offset LNBF so they still consider it at a F/D of .6. But it works better with the prime focus as the front end is set up for it. Would be interesting to take one apart and see what the actual physical difference is in the construction of the two different versions. Also I wonder what type of numbers an Iinvacom QPF 031 would give.

As you can see the DMC transponder is a bit weaker than some of the others but your test makes me confident that I will get acceptable numbers here in Hawaii. Thanks again for all your help.

You are the MAN!!!!

Eric

Originally Posted by jags1

WOW!!! Thanks so much Iceberg!!!

no problem...figured might as well try out the LNB

Those numbers are really great!! With the setup I have in Los Angeles on a 3 foot dish I'm lucky to get 30% on the DMC channel. It would often drop out.

what receiver did you have? SOme receivers read low on the meter.

I did figure out that I could fine tune the reciever by adjusting the transponder frequency to get the best reading. I read somewhere that the set frequency in the LNBF starts to drift as the LNBF gets older. So to get the best signal you have to compensate by readjusting the frequency in the reciever. Is this correct?

correct. And being here in Minnesota we see temps that range from almost 100 in July/August down to -30 or greater in the dead of winter. So the LNB's do take abuse but I have the same LNB on my motorized for 3+ years now and its usually still pretty accurate and dont drift as bad. A blind scan receiver will pick up the transponder frequency properly

Also it looks like that Geosatpro SL1P Prime Focus .6 KU LNB works the best, eventhough it has a F/D of .6. Must have something to do with the physical construction of the scaler rings in the front of that LNBF. Must be somehow different than an offset LNBF. Maybe the electronics are the same as what is found in an offset LNBF so they still consider it at a F/D of .6. But it works better with the prime focus as the front end is set up for it.

alot of the numbers for the db level I take with a grain of salt. I have an old Primestar LNB that is probably a .8 or even .9 and it can kick the butt of some of the "claimed" .3 units. Its more the stability that I like. As I noted, the .6 was pretty rock solid on the quality meter where other units the quality fluxuated. The rings may have something to do with it but might be for show

As you can see the DMC transponder is a bit weaker than some of the others but your test makes me confident that I will get acceptable numbers here in Hawaii. Thanks again for all your help.

When I first started the project I was only getting a 45 quality and I was like "oh this isnt good"....then I noticed the elevation of the dish had to be a little higher than what the C-Band LNB was set up as...I have markings on the elevation slide thing on the dish so I know where my true south satellite is (which is 93W) and the lowest satellite for my area. Once I barely raised the dish it jumped to 75.....tweaked skew and locked at 90. I put the pic in there as proof.

I did notice that on my motorized setup (30" dish) DMC is lower transponder than some others.

Originally Posted by jags1

:

So you can see getting the 1.8 meter dish is still the cheapest way to go. Two 1 meter dishes are close to the cost of the 1.8 meter, but I think I would really be compromising my reception capabilities with using 1 meter dishes.

Also with the 1.8 meter prime focus dish I still have the option to get the invacom QPF 031 and then just motorize the dish. The Invacom QPF 031, being a combo linear and circular LNB, works for both FTA and Directv. That setup would definately optimize my reception for both FTA and Directv!!


Eric

Wow those costs are a real bummer!! I sure see why you are stuck on the 1.8m, the motorised way is clearly the way ahead but again at a high cost for your location. I think I would try a cheap offset LNBF before the motor, with that size dishconversion and noise ratio figures are not worth considering.
Good luck and let us know how you get on

Iceberg,

Back in L.A. I have a Traxis reciever. I don't know how it compairs with other recievers regarding the metering. Also I thought that the .db level and the F/D ratio are two complete different things. I know that the specs for the .db level are often exagerated by the manufacturers. But the F/D ratio is just the "angle" that the LNBF looks at the dish. The lower the number the wider the angle. Prime focus dishes have a lower F/D ratio so the LNBF needs to have a wider illumination angle. The angle is determined on how the feedhorn is designed. But like you said, the numbers don't really mean anything. It's all about how well the thing actually works!! And again I want to thank you for taking the time to experiment in how well it all actually does work!! By the way, what is the elevation angle to hit that 97W up there in Minnesota? Here in Hawaii I'm looking at 21 degrees.

pedrogarcia,

Yes, shipping costs here in Hawaii are always a pain. Although this time I'm glad I can get something bigger for less money!! I think in the long run the 6 foot dish is going to work out real well for me. I will post results once I get it all together!!

Thanks again to all of you!!

Eric

Also it looks like that Geosatpro SL1P Prime Focus .6 KU LNB works the best, eventhough it has a F/D of .6.

I believe the ".6" is referring to the LNBs Sensitivity, not it's f/d ratio.
You can use an LNB that was designed for a smaller offset dish on a Prime Focus dish.
They sometimes do not perform as well, but as you can see, good results have been demonstrated.