adam/LoRa_APRS_iGate
1
0 Fork 0
mirror of https://github.com/richonguzman/LoRa_APRS_iGate.git synced 2026-10-31 02:51:58 +01:00
Code Issues 55 Packages Projects Releases Wiki Activity

433 MHz Heltec V3 Output Power #209

New Issue
Closed
opened 2026-10-05 05:49:43 +02:00 by adam · 12 comments
adam commented 2026-10-05 05:49:43 +02:00
Owner
Copy link
Copy source

Hi Ricardo - I just got a Heltec V3 up and running, and it measures +19.7 dBm output. I'm running on the USB connection. If I use the battery connection, will it get to +22 dBm? Do you know? It seems according to the Semtech literature that +22 dBm is available directly from the battery supply?

Hi Ricardo - I just got a Heltec V3 up and running, and it measures +19.7 dBm output. I'm running on the USB connection. If I use the battery connection, will it get to +22 dBm? Do you know? It seems according to the Semtech literature that +22 dBm is available directly from the battery supply? <!-- github-sync-id:3316409820 -->
adam closed this issue 2026-10-05 05:49:43 +02:00
adam commented 2026-10-05 05:49:44 +02:00
Author
Owner
Copy link
Copy source

you should get 22dBm +-1 dBm as per Heltec Datasheet.

i don't know if it would change from battery or usb but i guess it should be the same.

how are you measuring it? many measuring units can't measure bellow 1W.

you should get 22dBm +-1 dBm as per Heltec Datasheet. i don't know if it would change from battery or usb but i guess it should be the same. how are you measuring it? many measuring units can't measure bellow 1W. <!-- github-comment-id:3182006016 -->
adam commented 2026-10-05 05:49:45 +02:00
Author
Owner
Copy link
Copy source

I am using an out of calibration spectrum analyser as well as a Bird wattmeter with a 1 W slug tuned for the 400 MHz band. Same equipment I measured the LilyGO stuff with where I got +17 dBm. I'm pretty confident in the numbers. What I do see is that the firmware's webpage I loaded goes only to +20 dBm setting.
When I set it to +17 I measure about +17 dBm; set to +18, I get +18; set to +19, I get about +18.9.
The measuring equipment's not the issue.

I am using an out of calibration spectrum analyser as well as a Bird wattmeter with a 1 W slug tuned for the 400 MHz band. Same equipment I measured the LilyGO stuff with where I got +17 dBm. I'm pretty confident in the numbers. What I do see is that the firmware's webpage I loaded goes only to +20 dBm setting. When I set it to +17 I measure about +17 dBm; set to +18, I get +18; set to +19, I get about +18.9. The measuring equipment's not the issue. <!-- github-comment-id:3184108510 -->
adam commented 2026-10-05 05:49:45 +02:00
Author
Owner
Copy link
Copy source

some values are not available with the used library to control lora modules (RadioLib)

i guess 19 and 21 are not available at all.

what does it show for 20 and 22 on sx1262 boards?

some values are not available with the used library to control lora modules (RadioLib) i guess 19 and 21 are not available at all. what does it show for 20 and 22 on sx1262 boards? <!-- github-comment-id:3184681872 -->
adam commented 2026-10-05 05:49:46 +02:00
Author
Owner
Copy link
Copy source
Image
<img width="1196" height="538" alt="Image" src="https://github.com/user-attachments/assets/da916aae-5e1e-46d7-96bb-6cc73f928a83" /> <!-- github-comment-id:3185283836 -->
adam commented 2026-10-05 05:49:47 +02:00
Author
Owner
Copy link
Copy source

what does it show for 20 and 22 on sx1262 boards?

as I implied at the top of this thread, when I set the web page transmit output value to +20 dBm, I get about +19.7, which is reasonable. However, the web page configuration does not allow the tx output value higher than 20 dBm, so I can't go higher.

> what does it show for 20 and 22 on sx1262 boards? as I implied at the top of this thread, when I set the web page transmit output value to +20 dBm, I get about +19.7, which is reasonable. However, the web page configuration does not allow the tx output value higher than 20 dBm, so I can't go higher. <!-- github-comment-id:3185315191 -->
adam commented 2026-10-05 05:49:47 +02:00
Author
Owner
Copy link
Copy source

i did some "bellow the desk" corrections:

sx1278 get till 20
sx1262 if set as 20 do 22
.... i will have to fix this to get it free for each type of board

i did some "bellow the desk" corrections: sx1278 get till 20 sx1262 if set as 20 do 22 .... i will have to fix this to get it free for each type of board <!-- github-comment-id:3185731643 -->
adam commented 2026-10-05 05:49:48 +02:00
Author
Owner
Copy link
Copy source

hmmm. I am using the Heltec V3 board, as far as I know it is an SX1262. The LilyGO units with the SX1278 would not make more than +17 dBm without the "high power" bit flipped so this board definitely has more output power.
The equipment has been on for several hours now so should be relatively stable.
Currently powered via USB.
The left column is the value I set using the web configuration page for TX output power, the right value is the measured power.

+16 = +15.6
+17 = +16.5
+18 = +17.5
+19 = +18.2
+20 = +18.9

Now powered via battery connector with supply at 4.2 Vdc
+16 = +15.6
+17 = +16.5
+18 = +17.4
+19 = +18.3
+20 = +19.0

so there's no difference between USB and direct via the battery connector.

Next is to see what is the voltage at the SX1262 Vbat pin.

hmmm. I am using the Heltec V3 board, as far as I know it is an SX1262. The LilyGO units with the SX1278 would not make more than +17 dBm without the "high power" bit flipped so this board definitely has more output power. The equipment has been on for several hours now so should be relatively stable. Currently powered via USB. The left column is the value I set using the web configuration page for TX output power, the right value is the measured power. +16 = +15.6 +17 = +16.5 +18 = +17.5 +19 = +18.2 +20 = +18.9 Now powered via battery connector with supply at 4.2 Vdc +16 = +15.6 +17 = +16.5 +18 = +17.4 +19 = +18.3 +20 = +19.0 so there's no difference between USB and direct via the battery connector. Next is to see what is the voltage at the SX1262 Vbat pin. <!-- github-comment-id:3185906127 -->
adam commented 2026-10-05 05:49:49 +02:00
Author
Owner
Copy link
Copy source

please try 21 , 22 and even more to see what values you get or errors (which should appear over 22)

overwriting the rules of the webconfig...

please try 21 , 22 and even more to see what values you get or errors (which should appear over 22) overwriting the rules of the webconfig... <!-- github-comment-id:3186258780 -->
adam commented 2026-10-05 05:49:49 +02:00
Author
Owner
Copy link
Copy source

I cannot enter a value that is greater than +20 dBm. I get the same error. I have tried entering values of 21, 22, 23, 24, 25, etc., but the web UI rejects those.
I prolly could hack the firmware.

I cannot enter a value that is greater than +20 dBm. I get the same error. I have tried entering values of 21, 22, 23, 24, 25, etc., but the web UI rejects those. I prolly could hack the firmware. <!-- github-comment-id:3186476960 -->
adam commented 2026-10-05 05:49:50 +02:00
Author
Owner
Copy link
Copy source

I was noticing the same thing with the Heltec V3.2 915 MHz board (supposedly capable of +22 dBm) - the web UI will not allow a value greater than 20.

Just don't do what I did to try to work around it: change the live, in-browser 'lora.power' field's 'max' attribute to 22. It sure let me apply it, but then the module wouldn't boot up ;) I needed to re-flash to recover, which of course was quick / easy.

I was noticing the same thing with the Heltec V3.2 915 MHz board (supposedly capable of +22 dBm) - the web UI will not allow a value greater than 20. Just don't do what I did to try to work around it: change the live, in-browser 'lora.power' field's 'max' attribute to 22. It sure let me apply it, but then the module wouldn't boot up ;) I needed to re-flash to recover, which of course was quick / easy. <!-- github-comment-id:3186844185 -->
adam commented 2026-10-05 05:49:51 +02:00
Author
Owner
Copy link
Copy source

just to be clear: max is defined as 20

but this means: on boards with SX1278 is set up as 20. On boards with SX1262 it adds (internally) + 2, so this is really 22dBm.

i guess i will have to clear this out on the setup/config webpage to have the user selected value more transparent

just to be clear: max is defined as 20 but this means: on boards with SX1278 is set up as 20. On boards with SX1262 it adds (internally) + 2, so this is really 22dBm. i guess i will have to clear this out on the setup/config webpage to have the user selected value more transparent <!-- github-comment-id:3189011985 -->
adam commented 2026-10-05 05:49:51 +02:00
Author
Owner
Copy link
Copy source

this has been added for new release list of TODO

this has been added for new release list of TODO <!-- github-comment-id:3271012733 -->
Sign in to join this conversation.
No Branch/Tag Specified
Labels
No items
No labels
Milestone
No items
No Milestone
Projects
Clear projects
No projects
Assignees
Clear assignees
adam (Adam Wojcieszonek)
No Assignees
1 Participants
Notifications
Due Date
No due date set.
Dependencies

No dependencies set.

Reference: adam/LoRa_APRS_iGate#209