After a lot of tests I have to aggree , a second lnb at that OMT brings down the signal from 11.7 dB to 7.9 dB in my case .
The second port is closer to the waveguide , I made a adapter to attach the lnb at the same distance from the waveguide .
To my surprice , the lnb attached on that modded port is giving 0.3 dB more signal ( 11.9 - 12.0 dB ) fluctuating
Back to the original port , ( 11.4 - 11.7 dB )
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All the tests are done at 19.2 º E , then I moved to 42º E with still the drilled-out polaraiser between lnb and feedhorn .
Very weak signal , so I removed the feedhorn cover and put a plastic plate in the horn .
Nothing calculated just a blind guess ,only the diameter was depending .
To fit tight 9.4 mm at the beginning till 11 mm at the end , 37 mm long 1.6 mm thick .
Receiving Turksat Promo with 13.9 - 14.0 dB .
After changing the drilled-out polaraiser for a original polaraiser and another feedhorn with cover also 13.9 but 14.0 dB was not possible to reach .
Maybe the cover is guilty for that loss .
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