Hallo Michael, oh2aue
„25 MHz TCXO on the left is only just barely useable“. This is exactly the oscillator I bought and used in my solution. Thank you for the time you took to help me to understand my problems.
Once again, thank you all for the very valuable information for me. It is an honor to be with you on this forum.
Vy 73 de Marek DM6GAS
Could you please tell me what should be the signal level from an external generator if I want to use it to supply an LNB from which I have removed the quartz, in order to achieve greater stability.
Well, I have purchased a generator with very high stability of the 25 Mhz frequency it generates. It is 0.1 ppm, so it does not have to be better. I removed the 25 MHz quartz from the LNB and, according to many published descriptions, fed it with a signal from this generator. Unfortunately the result is not satisfactory. The signal received from QO-100 is 2 - 3 dB weaker than from the original LNB and its quality has clearly deteriorated. The situation has been repeated with 3 different LNBs - you can see them on the picture. The next picture shows sinusoidal waveform of the generated signal, which is not ideal, but still OK. In the descriptions of the LNB modifications and replacement of the quartz by a miniature TCXO, placed in the same housing, no one mentioned any deterioration of its performance. On the contrary.
I do not know where I am making a mistake. I would appreciate any suggestions, as maybe someone has already been confronted with a similar situation.
