C band LNB and polarization

[Jullius]

I'm getting ready to setup a BUD. I was fortunate to recently pick up a 3 meter Kaul-tronics and a 6 foot Star-Trak. I will be setting the 6 footer up first and then the 3 meter is going up in the country on my Dad's old farm.

I can handle the 6 footer on my own as this dish seems to be all aluminum (mesh and support beams) with a steel mount. It came with both a stationary pole mount and a polar mount. No actuator, so I will start out stationary.

The LNB on both of these dishes is a Cal Amp 31477. If I understand correctly these have a pulse controlled wire that switches between H and V.

Do newer C band LNBs not have this? My question is should I buy a new LNB so I can easily switch between H and V using just the RG6 cable? Am I correct in this assumption? I have a Fortec Dynamic receiver.

I will post pictures of the Star Track as I progress on this project.

 

[ikki]

> Do newer C band LNBs not have this? My question is should I buy a new LNB so I can easily switch between H and V using just the RG6 cable? Am I correct in this assumption? I have a Fortec Dynamic receiver.


Yes, having an LNBF (Which is voltage controlled for polarity) is well with it.

 

[Mr Tony]

agreed. I use the LNBF's that just change polarity with the cable. The receiver changes poalrity. Much easier then having 2 receivers (one to change polarity and one to tune the channel in)

If you have a digital receiver that has a polortor on the back (Pansat 3500, 2700 are 2 of them) then you shouldnt have an issue.

 

[B.J.]

I guess the decision here is relative to quality. These new C/Ku lnbfs are certainly convenient with respect to voltage polarity switching, but if you have one of these, you're stuck with a relatively low quality lnb. With a feedhorn made to accept real standalone LNBs, you have the option of using a relatively inexpensive lnb (probably similar quality to the lnbfs), or you can spend more money and get a real high quality LNB. Yes, it's inconvenient to have to use a 2nd receiver to do the polarity switching, but quality wise, I think it's worth it.

I use a polarotor feedhorn on C-band, which works quite well, however another option is to get one of those so called ortho (I think) feeds, which have separate horizontal and vertical LNBs. People that have these swear that the quality is much better, and with these, you could switch between polarities using a DiseqC or 22KHz switch.

This may be a moot point if an when some of these VBOX type movers get polarity control capability.

But bottom line is that most posts I've read from people who have experience with both CoRotor and Ortho feeds with quality LNBs have very little good to say about the quality of these C/Ku LNBFs. My own guess is that the LNBFs will work fine for most or all QPSK, but I really wonder how well they work on DVB-S2 transponders. My old Corotor with CalAmp and Norsat LNBs work OK on DVB-S2.

 

[equant]

Here's my homebrew solution. I've had it running now for at least a month, and it's been a dream...

Polarotor Servo Controller

 

[Jullius]

I will be getting a new LNBF to get around the polarity switching issue for now. Thanks for all the advice.