Project MOAN: Mother of All Nodes


#121

How are you controlling the heat in the box? Looked like it got pretty warm in there, so any suggestions?

Also, any sense for publishing a step-by-step walk through for the non-HWE’s in the house? :slight_smile:


#122

I will answer this ASAP.


#123

New range record: @amon and I hit the MOAN unit from 31.77 miles away! I also was able to talk to @Paul_Edward_Morris who was 18.4 miles away (unit to unit no meshing was needed!) no problem. Lots more details to come in the thread about this adventure but it’s pretty awesome that we were able to get such kick ass range!!!


#124

Exciting stuff! Thanks for sharing!


#125

George, I’ve been working on something similar for the past couple days and I shouldn’t be too surprised that others have had the same idea lol. I’m noticing that not all these goTenna Mesh circuit boards are the same but on mine I have surface mount pads on the battery side of the board for a MMCX connector and was thinking that if I solder one on and just use a adaptor after that to connect to an external antenna. My only question with that is if the pads were used only to test the built in antenna or if they were put there for an external. Also I bought the “sunny buddy” board from CO based sparkfun to manage a solar panel and larger Lipo charging with built in MPPT. So my project would have external antenna, gotenna mesh main board, surface mount MMCX connector ($3), MMCX to SMA cable ($10) the “sunny buddy” ($25) and 3000mah single cell Lipo ($10 maybe), small solar panel and a small container.
Here is the photo of one of my Mesh boards and the pads I’m talking about, if you know what they are there for I would be interested to know.thanks!


#126

Got to get to bed, will reply ASAP and in detail!


#127

It was my, @amon’s, and @Paul_Edward_Morris’s pleasure! It was one hell of an adventure!

http://meshcommunity.gotenna.com/t/sunday-10-8-2017-12pm-amon-and-george-on-mt-washington-4450-ft-give-us-a-shout-on-both-mesh-version-1/723/14?u=gua742


#128

@notjohn I’m looking at tapping in to that MMCX connector as well, should have the parts together next week. I believe the feed for the primary PCB antenna and the feed for the MMCX connector are separate and the RF front end chip will need to be told to use one over the other. That part is still a mystery.


#129

That’s an interesting thought… so I decided to pull out my multimeter to see if there was conductivity between the pads and the internal antenna. Testing between the four ground pads and the ground plane I was able to get a connection. Look at the photo below and see the two points I tested on the opposite site of the board and the center of the MMCX pads. The green highlighted point I was able to get a connection and the red was no connection. So I think you are correct perhaps…

I will upload a layout of that RF chip in a couple minutes…
okay here is the chip layout… from the datasheet it says that ANT1 and ANT2 can be changed by setting VRX1 & 2 and VTX1 & 2 to a combo of high and low


As a side note… this chip is able to do 33.5dBm PA Output Power

RFFM6904 Datasheet


Let's Build a MOAN (Mother of All Nodes)
#130

Thankfully VRX1, VRX2, VTX1, and VTX2 are all test pads on the bottom and easily accessible. :slight_smile:

The AUX_RX and AUX_TX text pads expose a serial console (lots of places to grab GND). These are under the battery. Issuing the “ant 0” and “ant 1” command appears to switch which antenna is used. “ant 0” pulses VRX1 and prints “Output selected on test connector”. “ant 1” pulses VRX2 and prints “Output selected on antenna”.

The console exposed over these UART pins is very similar to the USB console accessible on the original goTenna.


#131

Anyone in the Bay Area that wants to meet up and build one of these things? Patience with non HWE’s a plus.


#132

OK after some thought, I’d go off the 50 ohm +/- of the antenna why? Because the coax and antenna are made for 50 ohms. Mismatch is no good! DON’T leave SWR out of the equation! Thoughts: Go!


#133

Here is a short video I made because I worked a ten hour day hunting infectious disease. You might watch the video and think “Wow! That looks like fun!”, and you’re right it was! Special thanks to @amon for the nothing short of amazing video and pictures and to @Paul_Edward_Morris for being coms up quick fast and in a hurry. I hope you enjoy the video and as always: Thank you and more is coming soon!


#134

Hey guys…My wait is over! I have been sitting here in Canada patiently waiting for the arrival of my order of goTenna Mesh devices, I’ve been doing lots of reading as I follow a number of different threads. I’ve been particularly interested in the dialogue surrounding the MOAN. Needless to say, I’m quite interested in building one or more of my own.

I am not engineer, but quite tech savvy. I understand all of the components used in building the MOAN, but need some clarification with the actual soldering of the I was wondering if someone could clarify a couple of points with respect to the actual soldering aspect. Is it simply a matter of soldering the coax cable (LMR400) to the correct place on the circuit board or is there any driver required for the device to recognize the external antenna? Also, would it be better to leave the original internal antenna or somehow disable it?

In advance, thanks and I can’t wait to get a MOAN or two up and running to grow the MESH community up here in Canada!


#135

^^^^ This! I’m savvy, too, although would love more info on the wiring in general. I’ll try and do a write up if someone wants to send over crude video or photos.


#136

What was your altitude?


#137

Received a few MMCX jacks today and they go on great. It’s the Molex 73415-2061 50 ohms vertical surface mount MMCX jack, which I selected primarily because it was the cheapest one on mouser. You’ve really got to be comfortable with hot air rework to get it on. Presumably only the 2017 V1.0 goTenna Mesh board has a place for this connector?

Preliminary tests are good, but I don’t have a scope that goes to 1Ghz or an appropriate down converter to really test it out. I suppose my next step is to remove that little passive sitting between the amplifier and the PCB antenna to verify that the external antenna really is being used when selected.

Waiting on some parts from China. Hoping to use an MMCX to bulkhead SMA pigtail to have a weatherproof, and clean, antenna pass-through for a relay node that’ll sit on my roof.


Let's Build a MOAN (Mother of All Nodes)
#138

COOL! I’ve been too scared to pop my gotenna open so far.

Can I do this an still use the original antenna when external antenna adapter is not connected?

Is it possible to drill factory case and use a rubber bung when this connector is not being used?

Justin


#139

I can’t strongly discourage drilling enough, the antenna connector is on the side which has the lipo battery and any damage to that is real bad. Just getting the drill depth correct to not scratch the board would be difficult. That’s also presuming you have the V1.0 board inside. :slight_smile:

The case opens up pretty simply. Firm taps around the edge to break the ultrasonic weld and then a little bit of prying pulls the two halves apart. I used one of those metal “spudger” pry tools to open the case on mine.


#140

Can you provide some photos of how you’d advise attaching the external antenna?