Hi,
Does external 25Mhz reference to Lnb change the signal strength of the Lnb?
br Ismo
Hi,
Does external 25Mhz reference to Lnb change the signal strength of the Lnb?
br Ismo
It doesn't, if you do it right, that is, the circuit you're using to filter out the 25 MHz reference doesn't put a load on the 739 Mhz signal. Keep in mind that the coupling happens using a series resonant circuit that gives a high impendance except at the resonance frequency 25 MHz.
But, even a little attenuation does not hurt. Keep in mind that the input of the LNB defines the noise figure (and you're not touching that) and these things have a lot of gain (30-50 dB I read somewhere, not sure if this is right).
In any case, even if you'd load the 739 MHz a bit, there is plenty of signal and you probably won't notice.
At the same time, the original reference crystal oscillator smears signals a bit, but using the reference signals are sharp. Expect clarity of the signals to go up, depending on the stability of the xtal oscillator this can be quite a bit.