BOK New Bill of Materials

[Sean Widdows]

Radio: Station G2 - SMA Female

Cavity Filter: Airframes SMA Female x2

Antenna: RAK Wireless 6dB Fiberglass, N Connector (Taking suggestions)

Enclosure: Metal, Sealed, weatherproof. no bigger than 12"x12" with a depth of ideally 6"-8" for battery space. 

Battery: undetermined, need assistance

Solar: Size of panel needs to be determined.

Firmware: TBD based on what is agreed to be stable upon time of deployment. 

Factors needing to be determined, 

how to FULLY power the Station G2 from battery source to utilize LNR function.

size, type, capacity of battery needed. Battery size needs to power radio for 2 weeks w/o solar for long overcast periods. extreme temperatures needs to be accounted for when determining battery composition.

solar panel wattage to keep battery charged.

If for some reason a solar G2 build is too costly or requires a solar panel deemed too invasive of the space we were graciously allowed to use, downgrading to a 4631 RAK radio will be plan B to keep our footprint small.

Jeff, I am hoping to mount the enclosure to the structure with a short cable to the antenna (<2' run). The antenna would be subject to more wind than the enclosure could handle if it was mounted directly to an N connector bulkhead with no support. the antenna is pretty long so it would need to be clamped to the vertical pole directly like it is now.

[Jeff Scoville]

Sorry it has taken so long to get back to you.

The Station G2 will need to be powered at 12 volts to be reliable.  From the data I see online, average current pull is around 146 mA at 14.16 volts.  That works out to 2 watts average power usage. 

Unfortunately, that makes the Austin build battery and solar panel "out of the box" not suitable, since they run at 5 volts.

But there is a way around.  The V25 USB battery pack does have one USB-C PD port that can run all the way up to 12V/1.6 A (it is the one on top).  If I add one of these devices from Adafruit Adafruit USB Type C Power Delivery Dummy Breakout - I2C or Fixed [HUSB238] : ID 5807 : Adafruit Industries, Unique & fun DIY electronics and kits, I can tell the V25 to run at 12 volt instead of default 5 volt.  We then run that 12 volt to the USB-C adapter on the Station G2 and everything is good.

Then you would run your existing solar panel which is at 5-6 volts into the other USB-C Input Port.  You'll be capped at 2 amps, which means maximum of 12 watts charging.  Since the battery is 24 watts hours, will take around 2 hours to charge when solar panel is at max.

If we upgrade the V25 to a V75 (more $$ at $79), we get 72 watt hours.  At 2 watts average power usage, we would get 36 hours with no sunlight.

In contrast, the RAK4631 averages 0.3 watts, so it would last 240 hours on the same battery (10 days).

The killer is the RAK4631 only draws 0.18 amps during a transmit cycle, whereas the station G2 pulls 0.854 amps when the PA is operating near maximum.  Receive currents are comparable around 46 mA.  But when transmit is so much higher, life of the battery is lower.

However, if you reduce the SX1262 gain to 10 dbm instead of 19dbm, then the current load would drop back to comparable with the RAK4631 and you could get 10 days of life.  Would make sense as 10 dbm will result in 30 dbm output, which is within legal limits.

--Jeff AE5ME

[Sean Widdows]

Jeff, acquiring the v75s shouldn't be a problem. However I'm wondering if it's possible to hook up 2 or 3 v75s in sequence to extend battery life without solar. Do you think that's possible? (Or even necessary)

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[Jeff Scoville]

I don't think we'd get a high enough voltage off on battery to charge the other.  Don't think it is necessary as long as the G2 is run at 10 dbm drive.

--Jeff AE5ME