PLL vs DRO

7mdish

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Hello, anyone made any test to compare PLL LNB and normal DRO LNB? I tried 2 SMW PLL LNBs (Q-PLL series), obviously they have a very high OL stability, but I suspect that performances are lower than common (and cheaper) LNBs, particularly when receiving low signals. I don't think that S/N ratio is so important, values lower than 0.5 dB in Ku band can not add anything using a big dish, so I don't understand the differences. Any opinion or experience is appreciated. Thank you.
 

Vipersan

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AZbox PrmHD + OpnbxS9HD + Skybox + DrHD F15
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2 m+ Alcoa PF + BSC421 C-Band lnbf...
+SS2/TwHnS2-3200 pci/TBS6925 pci
1.5 Fortec Star -Gbox - HtoH Ku/Ka/C
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From my limited encounters and understanding...
PLL lnbs have a greater stability over DRO ..thus frequency drift can be considerably reduced ..
This being less important at lower frequencies such as those used in Cband ...becoming more important in the higher bands such as Ka ..
I really don't think there is any more serious gain to be had by using PLLs ..as the front end amplifier devices used are at the cutting edge in most quality lnbs as it is.
I have read that the increased stability offered by PLL is particular benificial for higher modulations such as 8psk and above ..but have yet to confirm this for myself..so comments welcomed.
Lastly ...PLL lnbs do draw more current ..thus generate a bit more heat in operation.
..remember higher temps are not your friend when it comes to internally generated electrical noise ..so can affect SNR levels significantly ..
So a PLL with high quality front end components ...a well designed filter and pcb layout ..and efficient heatsinks are the goal..
This is why they cost so much over DROs
All imo of course ..
Quite happy to be shot down with good counter arguements...???
rds
VS
 
Last edited:

BlindFaith

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The real benefits of PLL vs DRO are stability and retuning accuracy with closely spaced carriers with very low symbol rates.
 

Vipersan

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My Satellite Setup
IP9000HD +
TD110 Dish and TD88 Dish in Tandem
66°East to 60°West.
AZbox PrmHD + OpnbxS9HD + Skybox + DrHD F15
2x VboxII AZ-EL
2 m+ Alcoa PF + BSC421 C-Band lnbf...
+SS2/TwHnS2-3200 pci/TBS6925 pci
1.5 Fortec Star -Gbox - HtoH Ku/Ka/C
My Location
UK
The real benefits of PLL vs DRO are stability and retuning accuracy with closely spaced carriers with very low symbol rates.
...Indeed I'm hoping there will be benefits to owning a Cband PLL lnbf ...when I get my hands on one..
Amos 5 for example carries a good few Low SR 8psk channels ...some of which I can get about 5db from ..
Currently beyond by reach..
Maybe these _will_ be lockable with such a device ..
Only time will tell..
 

7mdish

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My Satellite Setup
CM 2.4m motorised offset dish, Viking Ku-band 2-ports motorised feed, 2 SMW LNBs, RC2000A, Dreambox DM920.
My Location
Milan, Italy
The real benefits of PLL vs DRO are stability and retuning accuracy with closely spaced carriers with very low symbol rates.
What you mean "very low symbol rates"? Maybe below 5000 or lower?
But as I said earlier, I suspect that SMW PLL LNBs are less sensitive compared to more cheaper LNBs, but obviously frequency drifting is greatly better. Thank you.
 

Vipersan

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My Satellite Setup
IP9000HD +
TD110 Dish and TD88 Dish in Tandem
66°East to 60°West.
AZbox PrmHD + OpnbxS9HD + Skybox + DrHD F15
2x VboxII AZ-EL
2 m+ Alcoa PF + BSC421 C-Band lnbf...
+SS2/TwHnS2-3200 pci/TBS6925 pci
1.5 Fortec Star -Gbox - HtoH Ku/Ka/C
My Location
UK
What you mean "very low symbol rates"? Maybe below 5000 or lower?
But as I said earlier, I suspect that SMW PLL LNBs are less sensitive compared to more cheaper LNBs, but obviously frequency drifting is greatly better. Thank you.
In my case I'm referring to symbol rates around 1000 > 3000
 
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