- Joined
- Jan 1, 2000
- Messages
- 16,233
- Reaction score
- 4,202
- Points
- 113
- Age
- 81
- My Satellite Setup
-
Triple Dragon, Dreambox 8000, Echostar AD3000ip, TBS6522,6925,6983 PCie cards.
Gibertini 1.25m motorised dish driven by the AD3000, with either Inverto BU Quad or Norsat / XMW Ka LNBs . SMW 1.05m + 3 other dishes. Speccy: Promax HD Ranger+
- My Location
- The Flatlands of East Anglia
Here is my effort at converting the Eutelsat KA-Sat Inverto Twin LNBF into a Band A receiving LNB.
It's not a magic solution - these LNBs are designed specifically for receiving the Saorsat FTA services in Ireland. However, it's possible to modify parts of the LNB's circuitry to access some or all of Band A transmissions, for instance ITN's Newsnet feeds and the Italian Unire and Teleippica feeds.
The modification consists of changing the local oscillator frequency to allow the IF output band to display by conversion of the received Band A spectrum any transponders available on whichever satellite has this band's transponders.
The Inverto is designed to receive circularly polarised signals, but I'm concentrating on the linear Ka transponders on Astra 1L, i.e the ITN Newsnet feeds and Teleppica racing feeds. This means there will be a reduction in signals using this LNB for these Vertical and Horizontal transponders, but it's possible to 'peak up' the respective V and H transponders by inserting a piece of dielectric card into the throat of the feedhorn at 45 degrees either side of the central position, depending on whether V or H polarity is required (see pic).
Modification of the LNB -
Tools needed - a diamond-tipped grinding wheel to fit a Dremel drill, for removing a small amount of ceramic from the replacement DRO puck. Don't try and use anything other than diamond-tipped - it'll merely polish the suface of the DRO and blunt your grinder! Having said that, I accidentally chipped a piece off one of the pucks I tried, and found it was resonating at the exact frequency I needed!
A spectrum analyser to display the LNB's oscillator's frequency. This may be able to be seen using Crazyscan; I'll check later to see if this will be possible.
Some pieces of PTFE (Teflon) sheet. Search e-bay for 'PTFE sample sheets', somebody sells three postcard-size pieces 0.25mm, 0.5mm & 1mm for around £3 post free.
The oscillator's DRO puck in the Inverto resonates at 10.6 GHz, and is doubled in frequency to 21.2 GHz for subsequent mixing with the Band B 19.7 to 20.2 GHz received by the LNB. It's using the lower mixing frequency to output an IF band of 1000 - 1500 MHz.
So, for Band A, you change the DRO to a 9.75 GHz puck, readily available from an old Ku LNB many ofus have lying around. Of the two DRO pucks in the Ku LNB (9.75 and 10.6 GHz, you want the one that is a little larger, i.e the 9.75GHz one. This needs to be raised in frequency to about 10.35 GHz by removing a small amount of ceramic from the puck using the Dremel grinder. Trial and error really, a little at a time until you have the correct frequency.
Method of removing the existing DRO puck and replacing with the new one to follow, also how to put the PTFE strips over the filters.
For now, some pics of the LNB circuit mod.
It's not a magic solution - these LNBs are designed specifically for receiving the Saorsat FTA services in Ireland. However, it's possible to modify parts of the LNB's circuitry to access some or all of Band A transmissions, for instance ITN's Newsnet feeds and the Italian Unire and Teleippica feeds.
The modification consists of changing the local oscillator frequency to allow the IF output band to display by conversion of the received Band A spectrum any transponders available on whichever satellite has this band's transponders.
The Inverto is designed to receive circularly polarised signals, but I'm concentrating on the linear Ka transponders on Astra 1L, i.e the ITN Newsnet feeds and Teleppica racing feeds. This means there will be a reduction in signals using this LNB for these Vertical and Horizontal transponders, but it's possible to 'peak up' the respective V and H transponders by inserting a piece of dielectric card into the throat of the feedhorn at 45 degrees either side of the central position, depending on whether V or H polarity is required (see pic).
Modification of the LNB -
Tools needed - a diamond-tipped grinding wheel to fit a Dremel drill, for removing a small amount of ceramic from the replacement DRO puck. Don't try and use anything other than diamond-tipped - it'll merely polish the suface of the DRO and blunt your grinder! Having said that, I accidentally chipped a piece off one of the pucks I tried, and found it was resonating at the exact frequency I needed!
A spectrum analyser to display the LNB's oscillator's frequency. This may be able to be seen using Crazyscan; I'll check later to see if this will be possible.
Some pieces of PTFE (Teflon) sheet. Search e-bay for 'PTFE sample sheets', somebody sells three postcard-size pieces 0.25mm, 0.5mm & 1mm for around £3 post free.
The oscillator's DRO puck in the Inverto resonates at 10.6 GHz, and is doubled in frequency to 21.2 GHz for subsequent mixing with the Band B 19.7 to 20.2 GHz received by the LNB. It's using the lower mixing frequency to output an IF band of 1000 - 1500 MHz.
So, for Band A, you change the DRO to a 9.75 GHz puck, readily available from an old Ku LNB many ofus have lying around. Of the two DRO pucks in the Ku LNB (9.75 and 10.6 GHz, you want the one that is a little larger, i.e the 9.75GHz one. This needs to be raised in frequency to about 10.35 GHz by removing a small amount of ceramic from the puck using the Dremel grinder. Trial and error really, a little at a time until you have the correct frequency.
Method of removing the existing DRO puck and replacing with the new one to follow, also how to put the PTFE strips over the filters.
For now, some pics of the LNB circuit mod.