These new portable 900mhz mesh networking transceivers are awesome!

They have 1 watt power output. Fractal Antenna. Links to your iOS or Android smartphone. Fits in your shirt pocket. Hardware hackable. SDK available.

I have already modified one with an external SMA antenna connector so I can use a higher gain antenna.  

They are already in use by a ton of people in the Bay Area as well as across the country.

Here is the link: https://gotenna.com/

You can also browse the user coverage map here: https://www.imeshyou.com/

It would be really cool if we could get these devices placed on top of ham radio repeater towers and mountain tops such as Mt Diablo, Mt Hamilton, & Mt Umunhum.

these devices would be an ideal way for non hams to have off-grid / emergency communications.   

This link will direct you to the goTenna Mesh community discussion board where you can read about how people are using and modifying goTenna Mesh devices: https://meshcommunity.gotenna.com/

Use this link to save $20 on any GoTenna purchase:https://www.takable.com/x/BgQPKo