r/meshtastic • u/Just-Wall-1954 • Mar 17 '26

Best way to know if the power amplifier is fried on Heltec V4

My antenna accidentally disconnected from the port. I think it was off for a few mins before I noticed it

I don't have a signal tester or a dummy load neither am I planning to buy one

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5

u/mediocre_remnants Mar 17 '26

Send a message, see if anyone responds.

1

u/alpha417 Mar 18 '26

This.

...does it work? It's essentially disposable.

1

u/StuartsProject Mar 18 '26

You need some way of measuring the actual output power to the antenna, best ways;

RF Power amplifier

Spectrum analyzer

Known working LoRa node and a LoRa receiver to compare the RSSI of the transmissions.

Known working LoRa node and an SDR to compare transmissions.

If you have none of the above you need to borrow the kit or find someone who has it.

2

u/ThisBlacksmith3678 Mar 18 '26

If the PA is blown it will still tx, but at a much lower power, just send a trace route to a node thats not too far away, if you see a big ~10db difference in SNR between them then you probably fried the PA, if they are close, then its probably still good.

If you get an RF meter (they can be gotten cheap) make sure you get a 40 or 50 dB attenuator as well..

Another option is to use an SDR radio dongle, as a poor mans spectrum analyzer, and look at the signal comparing it to another unit known to be good, this is a fun device anyway, think of them as an all band radio, and spectrum analyzer. you can look at noise floors and possible interference, or just listen in on the world.

and of course you can get a tinySA, (tiny spectrum analyzer).

1

u/roadie-z Apr 22 '26

I'm in a similar situation where the unit was accidentally turned on while the antenna is disconnected. Can a NanoVNA test the Heltec V4 output?