Claudio,
I don't think that Si5351 is the right choice for this SHF task. I played with Si5351 five years ago (Si5351 spectrum) and have a result of the output spectrum measurement. Si5351 is not a low noise synthesizer but a clock generator.
Please note when a signal from Si5351 will be multiplied in LNB's PLL by 390 times the phase noise will degrade by 52 dB.
Karen, ra3apw
Hello Claudio IK1RQX,
I would like to be understood correctly - I expressed my opinion and indicated the reasons for such a judgment.
It all depends on the specific task - for example, if you want to make a frequency marker, then it is quite possible that such a solution with ICS512 will satisfy someone. Although the rubidium source provides good long-term stability but it is not the best accuracy.
But I expressed an opinion on a concrete solution - the use of ICS512 as a reference source for LNB's 9750 MHz synthesizer - in my opinion it is necessary to look for other solutions where two conditions will be fulfilled simultaneously - good stability AND low phase noise.
I am waiting new PCBs to check other ideas for this task.
Karen, ra3apw
Alex, agree, I am not sure that it's a good idea to buy this "OSC101" board.
CTI OSC5A2B02 is a good OCXO for QO-100 station (I have the same in my QO-100 transverter).
I measured this 10 MHz OCXO's Allan deviation and phase noise (better than -150 dBc/Hz @ 10 kHz) - no problem and stable parameters.
IMHO, the reason of an issue is a PLL Clock Multiplier of previous generation on board. I made the similar test with NB3N502 few months ago and got PN level even 10 db worse that with ICS512.
73 de Karen, ra3apw
Hi SV8QG,
crystal filter can help to remove only harmonics from ICS512 but , unfortunately, will not help to make phase noise better... 
73 de Karen, ra3apw
Hello All,
FYI - some results of testing the formation of the 25 MHz reference signal for the LNB PLL and 40 MHz reference (for the VHF SDR ADALM Pluto) based on the ICS512 chip (PLL CLOCK MULTIPLIER) at http://www.ra3apw.ru/proekty/ics512_reference/. Please use Google translator.
The 10 MHz OCXO with phase noise -154 dBc / Hz @ 10 kHz acted as the main source of the reference frequency.
As a result: 25 and 40 MHz signals are formed, stability is good but the phase noise value (-99 dBc/Hz @ 10 kHz) is not good enough.
Use for QO-100 is not recommended.
73 de Karen, ra3apw
Hello Claudio,
thank you. This is preliminary (not final) test version of PA on MW7IC2725 on FR4 (not RO4003).
Level of 2 & 3rd harmonics are big enough (- 27 dBc for second and - 38 dBc for third) that's why additional LPF should be added on PCB.
73 de Karen, RA3APW
Hi Team,
Transmitter kit STC_7013 for QO-100 of three assembled and configured boards:
1) Transmitter Converter Board (TX_STC)
2) Reference Generator Board (OCXO)
3) RF attenuator / RF switch and stabilizer board (ATT_PTT_PS)
More details http://www.ra3apw.ru/qo-100-2/qo-100/
User manual http://www.ra3apw.ru/wp-conten…/STC_7013_V1R0_RA3APW.pdf
Text in Russian, please use Google translator.
73 de Karen, RA3APW
