Ultra Low Noise Crystal Oscillator with 1:4 or 1:8 fan out buffer


Main function blocks are seen on the block diagram below:

LO Module

XO is of a Driscoll type A design - there were only few documented ham radio experiments conducted so far - and it is a modified Uwe/DC8RI circuit (also check this design from Leif/SM5BSZ).
XO performance is achieved by using key components: high quality 5th overtone crystal, GALI-51 as sustaining amplifier, BFP196 as isolation amp and LT3042 for providing ultra low noise power supply.
Core XO is followed by an isolation amplifier and power splitter that feeds two 1:4 distribution boards (second distribution board is optional).
TX/RX sequencer drives high power relais (all in parallel) and provides 12V power supply for RX and TX converter(s) via LO output connectors (DC over coax).
Power supply outputs are configurable (RX, TX or zero voltage - only two outputs can supply TX voltage).
Phase noise plot (TKS to S53KS) of the final design shows excellent performance.

XO Phase noise plot 

Any 5th overtone crystal in the range of about 100 MHz to 150 MHz can be used in this design with only few passive component changes.
Few exqmples:
Output power level: +9 ... +13 dBm. @ 50 ohm
Phase noise data:
@offset Phase noise 
1 kHz -150 dBc/Hz
10 kHz -165 dBc/Hz
100 kHz -168 dBc/Hz
1 MHz -170 dBc/Hz

Few photos:

S5 XO front   S5 XO back

ULN XO view

ULN XO side view

The LO module can be used to drive two (or more) Javornik-144/14 transverters. See how to do the modification here.

The picture shows how S5 XO and RX converter were used for the first time at S59DEM contest station during July 2019 2m contest.
S5 XO + RX converter as used first time at S59DEM contest station

For more information contact Sine/s53rm(pri)hamradio(pika)si.
Date published: Aug. 2018
Change log:
- July 2019: added some description, pictures and phase noise plot of final design: added link to XVRT modification page.