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Equipment Tips

We try to bring you some infomation on equipment problems and the ways to possibly rectify. If you have and tech tips that you like to share just TechTips@satellitebyfibre.co.uk

 

Problems with Grundig SD FREESAT Receiver

 

The fault was that it would not switch to vertical channels from the IRS GTU. The receiver was tried on a standard dish set up and all worked fine, the GDU was replaced and the same fault was still present. I could get the GTU to work correctly with my Promax and a Humax HD Freesat.

 

Reply:-

I think that the LNB line voltage from the Grundig SD FreeSat is the problem and may be a bit high causing the GTU to switch to Horz. I have checked the LNB line volts on a Grundig  SD Receiver and found that the vertical is 14.94v , Horz. 20.29v this voltage would  be ok on a standard dish / LNB with a cable run of 15-30m and would get some volt drop but on a cable of 1.5m there is no drop. Some years ago I seem to recall that there was a problem with Pace receivers not switching some LNB’s and a 2v dropper was fitted in line.

 

Signal levels:- We have found that the MDU work best with a optical signal level below -5dBm. If you are only using a Fibre LNB and a Optical cable less than 200mts you will need to put in at least a 10db optical attenuator on the optical cable input to the MDU.

Most Optical LND's produce a optical power of +5dbm this level is the same no matter the size of the dish. Satellite power can only be mesure via the Global Fibre Meter or on the output of a MDU after it has be converted back to the coax IF freq of the satellite.

On some MDU there is a 10db switch, although this helps with BER at the recever, it is still best to get the optical power to the MDU to below -5dbm.