DRO ok?

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
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2i0jmt
Posts: 65
Joined: Tue Apr 16, 2019 2:48 pm

DRO ok?

Post by 2i0jmt » Fri Jul 19, 2019 1:15 pm

Hi Folks

Unfortunately, I just can't find any PLL rocket LNBs for sale :( I need a rocket-type for my POTY.

I have a Red Eagle Rocket LNB, that I believe to be DRO. During some testing with RX of 333 and above signals, it seems just fine, even though I think it's DRO.

Does this mean that DRO is typically ok for DATV?

I know that for NB SSB we'd need more stability, but I think SDR-Console can just fix the drift in software just fine.

Thanks

Jonny

G8GKQ
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Joined: Sun Mar 22, 2009 1:21 pm

Re: DRO ok?

Post by G8GKQ » Fri Jul 19, 2019 1:25 pm

Hi Jonny

Firstly, just because you are using a rocket lens on the front of your POTY does not mean that you need a rocket LNB behind it. I use an Octagon Quad (hacksawed) with my POTY and rocket lens.

Secondly, DRO LNBs vary a lot. Some are OK for DATV, but some tend to struggle at the lower SRs (250K, 125K). So possibly a temporary solution until you find a PLL LNB?

Dave, G8GKQ

g0mjw
Posts: 888
Joined: Sat Sep 20, 2014 9:15 am

Re: DRO ok?

Post by g0mjw » Fri Jul 19, 2019 2:46 pm

What Dave Said...

Plus, you can use an octagon PLL and for DATV you do not need to modify it, save cutting a hole in the plastic cover if you want to use the dual band patch feed.

http://www.hybridpretender.nl/
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Mike

2i0jmt
Posts: 65
Joined: Tue Apr 16, 2019 2:48 pm

Re: DRO ok?

Post by 2i0jmt » Fri Jul 19, 2019 3:15 pm

Thanks Folks

I forgot to mention, that I did do the cutting a hole in the centre of a normal Octogon PLL LNB thing, but had terrible results. What is normally a 7db MER+ on the Beacon ends up being around 4db MER :(

My unproven theory is that a POTY (with some type of lens on the front) is more familiar to a rocket LNB, than a normal LNB that effectively has its horn removed.

Are there any sources beyond ebay and amazon for good rocket PLL LNBs?

Thanks

Jonny

g0mjw
Posts: 888
Joined: Sat Sep 20, 2014 9:15 am

Re: DRO ok?

Post by g0mjw » Fri Jul 19, 2019 3:34 pm

2i0jmt wrote:
Fri Jul 19, 2019 3:15 pm
Thanks Folks

I forgot to mention, that I did do the cutting a hole in the centre of a normal Octogon PLL LNB thing, but had terrible results. What is normally a 7db MER+ on the Beacon ends up being around 4db MER :(

Jonny
How, exactly, did you mount the LNB? It is important the new lens is in the focus, (typically same place as the old feedhorn was). That's not so easy to do and generally requires adjustment in-situ.

Sawing off the horn is drastic, especially considering the investment at risk often exceeds €6, but it is the best way to go.
Are there any sources beyond ebay and amazon for good rocket PLL LNBs?
No. DRO only. The lens is easy to remove and re-purpose.

Mike

2i0jmt
Posts: 65
Joined: Tue Apr 16, 2019 2:48 pm

Re: DRO ok?

Post by 2i0jmt » Fri Jul 19, 2019 8:15 pm

I followed the exact instructions that you linked to :) Drilled a hole, and pushed pipe all the way back, and turned pipe to reduce flex.

I had MiniTiouner in front of me while I tried to make fine adjustments. The best I got was about 5dB MER max. I would imagine some non-rocket LNBs work better with a pipe than others. Mine is an Octogon Green PLL so if anyone has used a POTY with this LNB in this way, and has gotton better results, please let me know so I can try harder!

Cheers

Jonny

M0SKM
Posts: 253
Joined: Sun Jul 13, 2014 3:15 pm

Re: DRO ok?

Post by M0SKM » Fri Jul 19, 2019 10:00 pm

Jonny,
Sent you a PM earlier but you didn't spot it. :ugeek:
Take a look next time.

73 Steve

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