EXTTR details needed

[John Williams]

EXTTR is used to activate an external amp for transmitting. Does anyone know if EXTTR is actuated some time prior to the creation of RF in order to allow any T/R relays to settle prior to seeing RF. Conversely when transitioning to receive, does the RF cease prior to the dropping of EXTTR to ensure that the relays are stable until the RF has stopped, then switching to RX. 

I have been looking to see if this is documented anywhere. This would have to be a gateware function I am assuming. 

A further question is that if there is a hysteresis between these states, can it be changed by software. 

John W9JSW

[John Williams]

I think I just answered my own question. Looks like TX Latency controls the timing from start of transmission until RF is produced. PTT hang controls the PTT line after RF ceases. 

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From: John Williams <jswi...@gmail.com>
Sent: Saturday, April 11, 2026 8:47 PM
To: herme...@googlegroups.com <herme...@googlegroups.com>
Subject: EXTTR details needed