Problem with LNB on Analogue system

[dec4]

During a recent gale my 80 cm analogue dish with Nokia Universal LNB became damaged. I have since acquired an older 80cm dish with LNB ( no marking on case ). I can find Astra 19.2E with an older Cambridge decoder however when I connect dish to Nokia 800 SRD Analogue decoder all prestored channels e.g. Sky News, BBC radio etc.. have disappeared. Is there some system settings which need to be reset for older LNB or do I need to tune all signals in again? Any advice would be much appreciated.
Dec4

 

[2old4this]

The LNB contains a so-called local oscillator. This generates a signal of a particular frequency, such that when combined with the original microwave signal, a new signal results which is of a frequency suitable for successful propogation along a co-axial cable (the original "pure" signal would not manage this).

Different LNBs can have different local-oscillator frequencies - especially the older ones. This results in the combined signal having a frequency which is "offset" from the intended value.

Receivers usually have a feature which allows the offset to be corrected (look for a "local oscillator" value and match it to whatever is marked on the LNB if anything.

Alternatively, you can simply rescan, and bear the offset in mind each time you need to search for a signal at a particular published frequency.

2old

 

[dec4]

Many thanks for advice. Unfortunately there were no markings on LNB case so it took a little time to figure out that L.O. frequency was 10000 Mhz. LNB for Nokia receiver was set for 9750 MHz. Anyone suffering same problem in future might like to note that CNN is offset from Sky News by 250 MHz and therefore appears on channel where Sky News was originally stored.
dec4.