Advice Needed Dual KU C Band LNBs

[Spiff]

Good evening from a chilly Mullion Cove Cornwall.

Have any of you gentlemen experience with dual band LNBs ?

Reading around the net they would appear to perform, though it looked as if comparison's were between similar dual LNBs rather than separate KU and C band LNBs.

They are expensive because of the postage from the States.

Looking at one of the units it is tempting to cut a hole in the rear of the C band LNB I have and experiment : )

God Bless Spiff

 

[blademedia]

Hello Spiff, What size dish do you intend to use for C band + PF/OS dish, dishes 1.2 / 1.5 will only receive limited transponder's, a good way to start is get a cheap C band lnb and see who you go

 

[s-band]

I used to use Chaparral Co-Rotor which has a Ku dipole and reflector in the middle of the C band feed. It worked well on C band with a 3m mesh dish but I was never convinced about the Ku performance. It only gave a couple of dB over a 1.5m dish at Ku but that probably had as much to do with the f/d of the 3m dish and its construction. This is the current model The Corotor II Plus Feedhorns | Chaparral Satellite Components

As BM said, try a cheap LNBF. Adding a C band to the side of the KU worked ok, for me, on a 1.5m, within the limits of the dish size. Retro-fitting C-band to an old IRTE 1.5m PF

 

[Spiff]

Blademidea,

Thank you for your reply.

I intend using a 1.4 m prime focus, I have a Titanium C1W-PLL C Band LNB plus pole and brackets to install it.

The problem at this location is finding a spot out of the coastal winds, the Precision 1.3m Prime focus on KU band is occupying the best spot.

Having two large dishes in an area of outstanding natural beauty is also asking for trouble.

Though having Navy helicopters from Culdrose training over head is more of a detriment as far as I am concerned : )

The idea of replacing the 1.3 with the 1.4 and using a combined C / KU LNB would have solved the problem.

I am wondering though how good the KU band reception would be on a combined unit.

God Bless Spiff

 

[blademedia]

Hello Spiff, the combined unit (first picture) will perform poor on a small dish, from memory something like a 2mtr + dish its not so bad but not great, I would use the Tit with a KU off set/vice versa.

 

[Spiff]

I used to use Chaparral Co-Rotor which has a Ku dipole and reflector in the middle of the C band feed. It worked well on C band with a 3m mesh dish but I was never convinced about the Ku performance. It only gave a couple of dB over a 1.5m dish at Ku but that probably had as much to do with the f/d of the 3m dish and its construction. This is the current model The Corotor II Plus Feedhorns | Chaparral Satellite Components

As BM said, try a cheap LNBF. Adding a C band to the side of the KU worked ok, for me, on a 1.5m, within the limits of the dish size. Retro-fitting C-band to an old IRTE 1.5m PF

Good evening S-Band,

Thank you for your reply.

I shall try adding the C band LNB to the side of the KU as you have suggested, it sounds a good simple way to start : )

Omitting the scalar rings on the C band LNB to get a closer position perhaps?

God Bless Spiff

 

[scopus]

As others have said, forget the LNB in the first picture, Ku is extremely poor, especially if you insert the dialectic slab, which you will need for C Band.

 

[s-band]

Omitting the scalar rings on the C band LNB to get a closer position perhaps?

Hi, The scalar ring modifies the polar pattern of the open waveguide to ensure that the dish is correctly illuminated. If you don't use it, there's a chance that you will over-illuminate and get more ground noise. The signal strength will be about the same but the signal-to-noise ratio will be degraded. Having the feed a bit off axis shouldn't make too much difference.

 

[Spiff]

Hi, The scalar ring modifies the polar pattern of the open waveguide to ensure that the dish is correctly illuminated. If you don't use it, there's a chance that you will over-illuminate and get more ground noise. The signal strength will be about the same but the signal-to-noise ratio will be degraded. Having the feed a bit off axis shouldn't make too much difference.

Thank you S-Band,

I shall try it with and with out the scalar rings.

God Bless Spiff

 

[impala]

I used to use Chaparral Co-Rotor which has a Ku dipole and reflector in the middle of the C band feed. It worked well on C band with a 3m mesh dish but I was never convinced about the Ku performance. It only gave a couple of dB over a 1.5m dish at Ku but that probably had as much to do with the f/d of the 3m dish and its construction. This is the current model The Corotor II Plus Feedhorns | Chaparral Satellite Components

As BM said, try a cheap LNBF. Adding a C band to the side of the KU worked ok, for me, on a 1.5m, within the limits of the dish size. Retro-fitting C-band to an old IRTE 1.5m PF

in my corotor 2 plus the sun heated the ku band probe,so it skewed a bit.i managed to heat it up and straightened it.and after that it performed mutch better!it was 23 years ago and it still performs(i have weared out 2 servos)