Been playing around with a $39USD Arduino Kit I bought from Amazon.com and an Etherkit Si5351A. Total cost of this project was about $55 with shipping.
In the demo above the Si5351A is outputting 2mA or -7dBm or 0.1995 mWatts. http://www.cantwellengineering.com/calculator/convert/mA
The antenna I used is just a 6" long piece of wire. Nothing major there.
The code for the Arduino came from here: https://github.com/la3pna/si5351_beacon
With a few tweeks (just text message sent, and some timing and removal of a 30 second carrier tone), I had it running in about 10 minutes. Frequency is very stable, I bought the TCXO version of the Etherkit. It could be improved most likely by removing the TCXO and replacing that with a GPSDO freq reference. Which should lock it without an drift at all.
About 30 minutes after I shot this video the carrier really got stable. With no drift or wobble.
This is running at -7dBm or 2mA for this demo or 0.1994 mW
SI5351A: https://www.etherkit.com/rf-modules/si5351a-breakout-board.html (I bought the $15 version with TCXO)
* All SMT components assembled, 0.1" headers included separately
* Fully tested
* Output frequency range: 8 kHz to 160 MHz (see Constraints below)
* Number of outputs: 3
* Output impedance: 50 Ω
* Output drive levels: 2 mA, 4 mA, 6 mA, 8 mA (into 50 Ω)
* Power supply: +3.3 V or +5 V
* Interface: I2C (on a 0.1" header)
* Output jacks: 0.1" header or optional SMA female end launch
* PCB material: high quality 1.6 mm double-sided FR4 with soldermask and ENIG coating
* PCB dimensions: 30 mm x 50 mm
* RoHS Compliant
Two multisynths cannot share a PLL with when both outputs are less than 1.024 MHz or greater than equal to 112.5 MHz. This means that you may only have two outputs under those conditions.
Arduino UNO kit: http://www.amazon.com/gp/product/B016D5KUHS?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00