I will have to get one then, for now I will unplug the antenna, and use one of these:
There is a small but definite risk that you will destroy the RFM69CW module if you transmit without a matched load. If you must remove the antenna, you should use a dummy load which will absorb the radiated power; without it, the power that would have been transmitted is reflected back into the output stage and damage it. That will happen with or without that dust cap.
Well Robert, can you recommend a resistive cap to put on it?
A 50 Ω, 20 mW dummy load with a male SMA connector - something like one of these: https://uk.rs-online.com/web/c/connectors/rf-coaxial-connectors/rf-terminators/?searchTerm=SMA%20termination
Obviously, I don’t normally use USA suppliers, so I can’t recommend one local to you.
Or this from Mouser: https://eu.mouser.com/ProductDetail/Amphenol-RF/132360?qs=sGAEpiMZZMvlX3nhDDO4AEYzT3F9u7x30VsT5yxFn%2B4%3D
But the easy answer is to leave the antenna connected, just ignore the data that comes from the emonTx via the RFM and only use the WiFi values.
Okay, so lets finish this now.
I am going to pop the antenna back on, and not use the emontx node that connects via RF.
Can I connect the device to my emonpi, as another node or something, and just finish this?
I was looking at doing this I guess via MQTT, or HTTP but I do not know what is more reliable/what the difference is.
I just found my API key at /emoncms/feed/api, so now I just need someone to tell me to use MQTT or HTTP, and what to do first to name/connect the device correctly.
Do I add a node? Do I overwrite one of the nodes? What am I supposed to do here to connect this tx to my emon pi over EmonESP/Wfif…
I read:
and
I think I am going to use MQTT, but my node list is varied/how to I represent spaces…can I just create another node?:
I suppose that is what makes it confusing to start…I do not understand this at all heh.
I mean, I just went to setup Device Setup, and I see a node 15, 17, 30, emontx3, and a emontxshield
I guess that I understand that some of them are just preconfigured, but what for, and should I write over them with MQTT w/ this EmonESP…
So I was just reading this too:
https://learn.openenergymonitor.org/electricity-monitoring/networking/sending-data-between-nodes-rfm
So I am starting to understand some of these reserved nodes…but it still does not help me understand what configuration that I have to create to use HTTP or MQTT.
I don’t understand all that either, so I’m afraid I can’t help with that. EmonCMS should see the data coming in via Ethrnet/Wi-Fi as another Node - I don’t have an ESP8266 so I can’t even tell you how to set that up.
Robert,
Thanks for helping me so far. Eventually, once I get the WIFI piece sorted out, can I use the 50 Ω dummy loads on both the emontx and emonpi?
You could do that. The emonPi only transmits if you turn it on (for use with the long-gone emonGLCD), so there’s little point in doing that. It will continue to pick up any signals on the band, but just ignore them.
Is their an internal antenna then? How does it pick up signal?
I’m getting confused about what question you’re actually asking.
The danger, as I tried to explain above, is when the RFM tries to transmit and there’s nowhere for the power to go. If it’s only receiving - and there’s nothing you want to receive anyway - then there’s no need to remove the antenna, and no need to have it either.
The emonTx automatically transmits; the emonPi only transmits when you enable it in emonhub.conf. The external antenna for the RFM is not the WiFi antenna, that’s internal, on the Raspbery Pi itself.
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@Robert.Wall sorry for the confusion. I understand your question.
I am just trying to get rid of the 433Mhz broadcast completely from any device, and disable reception of it also. I do not use it, and I have not had enough time to evaluate it from a vulnerability standpoint.
I do not have the UART I need right now, so I was just going to cap both devices if I could with the 50 ohm cap that you mentioned. This one right here: https://www.mouser.com/ProductDetail/Amphenol-RF/132360?qs=sGAEpiMZZMvlX3nhDDO4AEYzT3F9u7x30VsT5yxFn%2B4%3D
Later, once I get some of this work unloaded, I was going to jump into the sketch in the EmonTX device, and see what I can do with the EmonPI.
Tweaking the emonTx sketch is fine.
There’s little you can do with the emonPi sketch. It’s automatically reloaded every time you update the emonPi - unless you know the trick and update your emonPi as an emonBase, which fortuitously breaks the update in just the right place. Don’t ask me why it was done this way, all I can think of is “It seemed a good idea at the time.” That’s turned out not to be the case, IMO.
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The emonPi update has now been broken out into several sections. The user can choose to update only Emoncms if required:
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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.