EchoLink VOX release causes very short spurious carrier at end of transmission

[EA7LLF]

Hello everyone,

I’m experiencing a strange behavior with an EchoLink Sysop node using VOX and I’m trying to understand whether this is a known issue or a configuration limitation.

• While I am speaking, everything works normally.
• When I stop speaking, the RX audio level drops to zero as expected.
• Exactly at the moment the VOX releases (end of audio + VOX delay), a very short spurious carrier is generated.
• Remote stations clearly hear a brief carrier “blip”, as if the transmitter keys again for a few milliseconds.
• In the EchoLink VU meter, the green audio bar goes to zero, but the red peak indicator briefly jumps almost to full scale at VOX release.
• This happens regardless of Squelch Crash Anti-Trip setting (tested from very low to high values).
• Receive Hang Time does not eliminate the issue.
• The behavior seems tightly correlated with the VOX release timing, not with RX re-triggering.

My setup is basically

• EchoLink in Sysop mode
• VOX-based RX control (no hardware COS)
• Simplex node
• Radio: Baofeng handheld
• PTT controlled by EchoLink (no hardware PTT hang/delay available in the radio)

Has anyone seen a similar effect where VOX release + VOX delay causes a very brief TX re-key or RF transient?

Is this a known limitation when using VOX with certain radios (e.g. Baofeng), and is the only real solution a hardware PTT release delay or different radio/interface?

Any insight from experienced EchoLink sysops would be greatly appreciated.

Thanks in advance.