Octagon PLL Twin Mod Help

Digital ATV - The latest generation, cutting edge ATV - Please discuss it all here.
Forum rules
This forum is run by the BATC (British Amateur Television Club), it is service made freely available to all interested parties, please do not abuse this privilege.

Thank you
Post Reply
MM0SAJ
Posts: 6
Joined: Sat Jan 08, 2022 4:36 pm

Octagon PLL Twin Mod Help

Post by MM0SAJ » Fri Jan 21, 2022 8:00 pm

Hi there all hopefully I have posted this new topic in right section if not I apologise.

I have recently bought the Octagon PLL Twin Green HQ OTLG LNB 0.1dB on ebay

https://www.ebay.co.uk/itm/353490874396

and have had the modification done for Variant 2 version from the following linked pdf file.

https://cdn.website-editor.net/ae24dc3e ... B_1_en.pdf


Please can someone help with regards to what I need to do next, i think I need an external Ref as in the modification the 25 mhz crystal is removed.

I am new to this side of the hobby and basically want the LNB to have 2 RX outputs First one for My Adalm pluto for RX Narrowbands SSB And other For RX Wideband DATV with my Minitiouner any help would be much appreciated kind of lost here.

Regards

Steve

MM0SAJ

G1BVI
Posts: 282
Joined: Wed Aug 02, 2017 7:32 am

Re: Octagon PLL Twin Mod Help

Post by G1BVI » Sat Jan 22, 2022 9:11 am

Hi Steve
Welcome to the world of QO100.
The reason you have modified your LNB is to get better stability and lock it to your own reference.

Personally I use an Octogan twin LNB others use Bulls eye etc. and I have not found it necessary to do this.

On SSB RX I use SDR Console which has the ability to lock to the beacon keeping you on frequency.

With your dual LNB you have removed one output and converted it to a 25MHz input.
Without this input the LNB will not function.

You therefore need to feed your LNB with your locked 25MHz ref (you could change this if you want to RX on say 70cm?)
You have ONE RX output that you can then feed to your RX.
The RX can be a SDR or one of the BATC DATV Rx's.
If you put a bias T and a splitter in between as I do you can then switch between 12v or 18V to change polarisation, ie. switch between SSB and DATV.
In modifying your LNB you have made it into a single output LNB.
Is that helpful?
Regards and
73

Nick

MM0SAJ
Posts: 6
Joined: Sat Jan 08, 2022 4:36 pm

Re: Octagon PLL Twin Mod Help

Post by MM0SAJ » Sat Jan 22, 2022 12:06 pm

Nick thx for your reply. My set up at present without this modification is as follows


Adalm Pluto REV C (All mods done PTT & TXCO for Drift)

DX Patrol Amplifier ( https://www.dxpatrol.pt/files/AMP2.pdf ) thx VOX system was terrible so now have the pluto PTT which is better

Ice Cone Feed (V2) https://www.qrz.com/db/DC8PAT#ICFv2

Bullseye LNB For Receive ( I have another one if I have to put up another dish for RX)

MinitiounerPro V2 (NIM Serit FTS-4334L)


So could I just use the bullseye LNB and switch using bias T and a splitter if so can you give a link to these items so I can order.
Basically I have another 80cm dish and another bullseye lnb but I dont think the wife will be to pleased if I put up another dish.

Thx for the Help Nick

Cheers

Steve

MM0SAJ

G1BVI
Posts: 282
Joined: Wed Aug 02, 2017 7:32 am

Re: Octagon PLL Twin Mod Help

Post by G1BVI » Sat Jan 22, 2022 6:42 pm

Hi Steve
You can use either LNB but the bullseye as standard would be easier to set up.
The Ice cone feed looks interesting, I use something that is now called a POTTY,
both sit at the focus of the dish as per the pictures of the Ice cone and so you only need the one dish.

I am still learning but I have discovered that my 0.9m dish only gives me a received MER of 6 from the beacon.
This means that I struggle to resolve other signals.
for DATV you will need a 1.2m dish IMHO or bigger for RX.
I shorted my Mini tiouner input and so I use a Bias T.
I purchased a DC to DC up converter from ebay and put it in a box with a switch so I could feed the Bias T with 12V or 18V.
Take a look at some of the pages from F1ATB for ideas (all in English)
For SSB an 80cm dish is fine
For DATV you need max power to your helical ICE CUBE so mount amp under the dish.
I lose 4dB on transmit with my system so need to do this myself.
The amp ideally needs to be hard switched on, I just turn it on and transmit.
Noise in the shack is an issue for me with the fans so another reason to put it outside.
Make sure box is waterproof but also that there is adequate ventilation.

Did I answer all ? :-)

73

Nick

MM0SAJ
Posts: 6
Joined: Sat Jan 08, 2022 4:36 pm

Re: Octagon PLL Twin Mod Help

Post by MM0SAJ » Sun Jan 23, 2022 7:04 pm

Thx Again Nick for reply I decided today to put up the 80cm dish for SSB narrowband RX and is lined up fine. I use the 100cm dish for DATV RX and the ice cone potty for TX only problem on both Narrow and wideband as the Junction Box with tx about 1m of cable used for tx low loss,Problem now is and I dont Know why but I run minitiouner and get all green light on the video beacon the c/n mer is 7.5dB and D4 and it isnt receiving have moved the skew and still the same with Video at 87% Overhead 4.5% Null Packets 3.2% and Audio 5.2% .
Yes I will invest on a bigger dish in a few weeks time for DATV.

Cheers

Steve

MM0SAJ

G1BVI
Posts: 282
Joined: Wed Aug 02, 2017 7:32 am

Re: Octagon PLL Twin Mod Help

Post by G1BVI » Mon Jan 24, 2022 9:37 pm

the ice cream cone is designed to work with an LNB so you only need the one dish that you can use for both DATV and SSB.
Those figures sound like you should be ok.
Have you tried Mini tiouner on sky to prove it works.
I could not resolve the beacon when I tried an 80cm dish
Others have so they may be able to give you more help.
Try Hi sat for a bigger dish he is in N Wales

73 Nick

g0mjw
Posts: 2327
Joined: Sat Sep 20, 2014 9:15 am

Re: Octagon PLL Twin Mod Help

Post by g0mjw » Mon Jan 24, 2022 10:56 pm

If you have all green lights and the transport stream is being received it is more likely to be a problem with the video codecs if the transport stream statistics are updating OK. I assume you tried the render with VLC option.
Temp.jpg
Temp.jpg (445 KiB) Viewed 2861 times
When you ran the test application as per instructions what did you get? If you record the TS can you play it back in VLC?

MM0SAJ
Posts: 6
Joined: Sat Jan 08, 2022 4:36 pm

Re: Octagon PLL Twin Mod Help

Post by MM0SAJ » Wed Jan 26, 2022 10:06 pm

thanks for all your help everyone, last night i received ok and managed to see video so now I have ordered the 1.1m dish as the 1.2 is only fibreglass version and very expensive so should be better if not will upgrade again but its getting an eyesore for neighbours if it gets bigger. It has arrived but high winds next few days so will do when weather better. After that may need help on the tx side of things thx all for helping me would be lost without the help much appreciated.

Cheers

Sreve

Post Reply

Return to “DATV - Digital ATV”