Roman,

I also have concern and posted previously this question regarding Receiver Input Protection.
The block diagram you reference shows that the unused ports of the relays open, not grounded.
I think a true schematic, or PCB layout, would be better suited to resolve this question.

Tom W3FRG

Hello Tom.
You are correct, it's not a complete schematic, there are also 3 additional relays which:
1. Ground each antenna port when TRX is switched off
2. Ground VHF port when you operate on HF
3. Ground HF ports when you operate on VHF

Hello everybody,
By the way, when we transmit or do the Auto - Tunner without an antenna for a few seconds only with 100w in FM,
do you have some kind of protection in any of the antennas, or not really...?

Thanks