Hi all,

Have been working on getting zero drift and frequency stability on one of my U3S units.

So far...

- Added a small heat sink on top of the 27 mhz xtal

- Packed the area around the xtal between the SI card and the bottom of the LPF board with cotton wool to keep the air currents on the 27mhz xtal. Unit is in QRP labs case as well.

- Set the park mode to 2 with a frequency of 150,000,000

- orientated the LPF board and TX schedule from highest to lowest frequency

- calibration set to 10 020

- added to the end of the frame a slow hell tx so to transmit and leave 30 seconds for calibration.

The results are that every band except 20 meters shows 0 drift.  It can run all night and it doesn't change.

Can anyone give some in-site on this..could there be something off with the LPF for 20M..

Thanks in advance..

Vernon - VE1VDM / VA1VM