Author Topic: [Hack] Extending the bluetooth range of the 121GW  (Read 211 times)

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Offline gnif

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[Hack] Extending the bluetooth range of the 121GW
« on: September 19, 2019, 09:32:19 am »
Recently I have found the Bluetooth feature in the 121GW invaluable, however it's range is a bit lacking and upon inspection it's clear why. The Bluetooth module is behind an EMI shield and behind the batteries. I didn't want to alter the meter by removing/altering the EMI shield, it's clearly required, so instead, I modified the Bluetooth module for an external antenna.

A quick google turned this up, it's pretty simple to do, but you must be ready to work with extremely fine pitch parts (I lost the capacitor and had to steal one from a donor Bluetooth module).

https://www.silabs.com/community/wireless/bluetooth/knowledge-base.entry.html/2015/08/06/_how-to_modify_ble-QAnI

Once done, I grabbed a WiFi antenna (seems to work well enough) and cut it apart and down to fit it inside the chassis without making any alterations. Just used some hot snot to keep it in place.

Did it work? Yeah!

Before I could get a flakey connection from the adjoining room (~5M), now I can connect to it from the other end of the house (~20M away).
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Offline Terry01

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Re: [Hack] Extending the bluetooth range of the 121GW
« Reply #1 on: September 19, 2019, 09:35:09 am »
Nice job!  :-+
Sparks and Smoke means i'm nearly there!
 
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Offline thinkfat

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Re: [Hack] Extending the bluetooth range of the 121GW
« Reply #2 on: September 19, 2019, 11:48:40 am »
Nice job! What size is that capacitor? Smaller than 0402?
 

Online PA0PBZ

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Re: [Hack] Extending the bluetooth range of the 121GW
« Reply #3 on: September 19, 2019, 11:59:52 am »
Nice job! What size is that capacitor? Smaller than 0402?

The article says: 27pF/6.3V/C0G (package: 0201)
Keyboard error: Press F1 to continue.
 

Offline mikerj

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Re: [Hack] Extending the bluetooth range of the 121GW
« Reply #4 on: September 19, 2019, 12:42:11 pm »
Useful mod, but I would be a little concerned that the antenna is held with hot snot just above the input terminals.  If it falls down and shorts something out you'd have quite a surprise if you tried to measure a high energy circuit (with the Cat rating of the meter I mean).
 

Offline gnif

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Re: [Hack] Extending the bluetooth range of the 121GW
« Reply #5 on: September 19, 2019, 01:03:16 pm »
Good point, I might throw some epoxy in there instead
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Offline ThomasDK

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Re: [Hack] Extending the bluetooth range of the 121GW
« Reply #6 on: September 19, 2019, 05:02:57 pm »
Recently I have found the Bluetooth feature in the 121GW invaluable, however it's range is a bit lacking and upon inspection it's clear why. The Bluetooth module is behind an EMI shield and behind the batteries. I didn't want to alter the meter by removing/altering the EMI shield, it's clearly required, so instead, I modified the Bluetooth module for an external antenna.
I would call it a "fix" rather than a "hack"... That's a pretty awful RF-layout  :palm:

These modules are meant to be mounted at a board edge, with no copper near the antenna. Someone didn't read the datasheet:


839406-0
 


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