Polarizer

Likvid

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#1
I have a question about polarizer as it seems nearly no one uses them today.

I haven't been into satellite TV since 1993 when i had a 2,4m dish with the Chaparall Monterey receiver and a Chaparall corrotor...

Things have changed drastically during the time and i am considering getting a much smaller motorized 90 cm system to play with.

Doesn't people use polarizers anymore with their motorized systems?

You need to skew the LNB polarizations at extremes....

So where can i buy one today or is it integrated into the LNBs today?
 

Llew

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#2
Hi Likvid

The last time I used a polarizer was in the early 90's for my SMW LNB/Offset dish and Echostar SR50 receiver. In order to provide a decent amount of current to the (magnetic) polariser over a long cable run, I had to construct a separate bit of kit to boost the supply. Also, these polarisers introduced a dB loss.

With Universal LNB's and offset dishes, the need for skew adjustment is not really an issue, although slight manual adjustment on weak signals can help.

I seem to remember the corrotor was an electromechanical device that often seized up!

Llew
 

Likvid

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#3
Yes the Corotor was a real signaleater at Ku-band, but worked really well in C-band and S-band.

I did have a Winegard 2,4 meter and later the 3,0 meter Pinnacle model which is the best dish i ever had, unfortunately Winegard doesn't make these excellent dishes anymore.

The SMW Ferotors was really good as you got only like 0.1dB loss compared to mechanical polarotors or polarizer that could get losses up to 1dB.

The Chaparall Polarotor was the best, sadly i throw away all these things when i moved once and didn't think i would get into satellite as a hobby again.
 

apogee2010

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#4
Likvid said:
The SMW Ferotors was really good as you got only like 0.1dB loss compared to mechanical polarotors or polarizer that could get losses up to 1dB.

The Chaparall Polarotor was the best, sadly i throw away all these things when i moved once and didn't think i would get into satellite as a hobby again.
I had always read that mechanical polarotors introduced less noise than ferrotors, their main disadvantage being moving parts prone to mechanical failure - is this wrong?
 

Llew

cerca trova...
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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
#5
apogee2010 said:
I had always read that mechanical polarotors introduced less noise than ferrotors, their main disadvantage being moving parts prone to mechanical failure - is this wrong?
Yes apogee, if I remember, it's the twisting magnetic field in the polariser that made them lossy. Polarotors just rotate the probe to select the polarity.

Llew
 

Channel Hopper

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#6
I still use the mechanical polariser and a full band LNB

I find for getting the maximum signals from low elevation satellites this system is the best .

Avoid Corotors as they are terrible at Ku band
 

Likvid

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#7
The Corotor was horrible in Ku-band but excellent at 4GHz...

The SMW Ferotor was the best as it only had losses up to 0.1dB.

However i liked the Chaparall Polarotor for Ku-band the best and Seavey Engineerings Polarizer, they had slighly higher lossses but produced excellent results and reliability.
 

apogee2010

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#8
I'm currently using a corotor on a Channel Master 2.4M dish. C-band works well, but I often wonder how much better Ku-band reception would be with a separate feedhorn setup.

So the $64,000 question - which route should I go down : a Chaparral mechanical polariser and feedhorn like this
http://www.chaparral.net/Ku Wideband Polarotor.html
or a SMW ferrorotor XF 45 and feedhorn (SMW XM-140 Prime focus)
http://www.smw.se/products/feed2.htm

or something entirely different???
 

Channel Hopper

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#9
Whats your budget ?
 

dago

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#10
the answer to your question is no, now a days its done with voltage control,

all done auto by the receiver, great machine the chaparral monterey 40,
the dogs bo***cks at it time, i was a great fan for many years.
 

Channel Hopper

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#11
Voltage control doesnt help with low elevation skew adjustment, which is more important on a prime focus dish.
 

apogee2010

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#12
I guess max would be about €150, so something like Seavey stuff is probably out unless it was secondhand on Ebay. I already have spare WR75 LNBs.
 
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