EmonTX - Wireless Disable - Switch to WIFI + Change to US Mode

I don’t think there is much risk running RFM69/RFM12 with no antenna. The emonTx on our office and my house have been operating without an antenna for several years with no issue. The transmit power is very low.

The antenna wire on the emonTH is far from being a 50 ohm matched load.

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Which is exactly why your system has operated OK for such a long time.
At low power levels, the reflected power is low, which is a non-issue. But…
if the module is operated at full power, there’s a definite risk of permanently damaging the module.

From the JeeLabs Shop page:

N.B.: An antenna must be connected to the module. A quarter wavelength wire – 82mm for 868 MHz – works fine (not included). Caution: operation for extended periods without an antenna at the higher transmitter power levels risks permanent damage to the output stages.

Ref: The JeeLabs Shop - RFM69CW Radio

This applies only to the high power variant of the RFM69. The RFM12, and low power versions of the RFM69 transmitter output level is considerably less than that of the high power version, so operating sans antenna poses little or no risk of damage.

Operating the high power version of the RFM69 at a low power level sans antenna, would also pose little or no risk of damage.

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But I think not before @neoweb acquired his system.

Are those changes generally available now?

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Yes in 9.9.9 (though other modules vanish from the menus until 10 is released to stable).

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I put the 50 ohm loaded caps on tonight. So far so good.

Is there any reason the EmonPi would have started to receive better with one on it?

It seemed like it did. Weird/unique?

You’ve got an emonESP and an emonPi. You didn’t think the 433 MHz inbuilt radios would work in your location, which is why you got ESP. But they did and you got your emonTx data appearing twice - one version by 433 MHz radio and one by Wi-Fi via your router. To stop this happening, you’ve put 50 Ω terminations in place of the antenna on both emonTx and emonPi.

Now you’re saying that the emonPi receives the emonTx on 433 MHz better than before?

We know that dummy loads like this don’t completely absorb all of the power, and that a little does get radiated, but the signal should be very low level by the time it’s received by the emonPi.

If receiving the data twice is really so inconvenient (remember it doesn’t get saved and cost storage space until you send it to a feed), then it’s time to invest in a programmer and embark on the learning curve that will enable you to stop the emonTx from transmitting.