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Message started by tearepa13 on Apr 13th, 2012 at 12:11pm

Title: Long C-Band feed
Post by tearepa13 on Apr 13th, 2012 at 12:11pm
I'm looking for a long throat feed for a 4.5M Prime focus C-Band dish, Receive only, it must be linear dual feed (x2 lnb's) and be longer than the Chaparral dual feeds...this is because of the congestion at the feed (support arms) support won't allow the standard 8" Chaparral with 2 norsat LNB's to rotate or acheive a closer f/d...my question to anybody out there is there a model which can be extended in length or a longer than standard feed?
The proprietry feed that comes with the setup is very expensive and unfortunately not a viable answer to the problem.
This instance arose because we changed over from circ to linear and no-go to alter the original feed.

Title: Re: Long C-Band feed
Post by Eric Johnston on Apr 13th, 2012 at 3:10pm
My first thought was "just remove the polariser or set the polariser at 90 deg instead of 45 deg", but maybe you can't rotate the LNBs gradually to set the linear polarisation adjustment amount.

Has anyone ever merged two L band signals via a 4 port coupler/hybrid to see if it is possible to extract linear two polarisations if the lengths of the input cables are adjusted carefully ?  Do you need external reference PLL LNBs with the same external reference 10 MHz supply ?

Best regards, Eric.

Title: Re: Long C-Band feed
Post by tearepa13 on Apr 14th, 2012 at 4:27pm
The original polariser is encased, and yes unable to rotate the feed when the pll lnb's are attached...there's just not enough feed tube to move vertically for clearance then rotate for xpol.
I thought there might be some Russian model with this extra length in the feed tube, or some add-on by Prodelin. We actually tried to join two chaparral feeds together, the cable-end being the dual feed and a sawn-off single for the incoming wave but it's attenuating too much (as a back-yard solution)...so yes it's working but not well.
Theres a dedicated tanberg receiver for each port back at the head so we are unable to simply switch it with a dual port lnb.

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