TX Power Output, TX Issues.

[Pytlicek]

Device: LibreSDR (https://vi.aliexpress.com/item/1005005165734650.html)
Firmware Version: Prebuilt firmware from OpenSourceSDRLab
Software Used: SDRconsole via LAN/USB

---

Description

We are using a LibreSDR purchased from AliExpress for satellite communication as part of our university radio club project. However, we are experiencing significant issues related to the power output and TX switching behavior with the prebuilt firmware.

Observations

1. Low Power Output:
   When transmitting in CW mode, the measured power output is only -7 dB to -4 dB, which is significantly lower than the expected 7 dB. This measurement was taken using a calibrated spectrum analyzer.
   Measures:
   Via LAN: @2.4GHz = -5dBm
   Via USB: @2.4GHz = -7dbm
   Via LAN: @145MHz = -3dBm
   Via USB: @145MHz = -5dBm

2. TX Switching Problem:
   The device does not seem to properly switch between TX0 and TX1 when attempting to change the output channel. Regardless of the settings used in software, the device always transmits from TX1.

Testing and Setup

• We have used prebuilt firmware without any modifications.
• The same issue with release v0.3.8 (overclock_cpu900_ddr650.tar.gz)
• Tried various setups with different cables, stabilized power sources, and configurations.

Request

We suspect there may be a problem with the firmware, especially regarding the TX switching and power output. Could you please provide insights or advice on how to address these issues, or suggest modifications to the firmware to resolve this?

[4Z1ZV]

You are in a much better shape than me.
I get -26 to -28 dBm & 2.4 Ghz with few fw including the overclocked.

Can you send a link to OpenSourceSDRLab fw ?

I read some comments who claim that it is HW issue with the lines from the connectors to the common mode transformers, but the traces looks fine.