I get Motorola Saber I (Securnet-S) with NTN5833A module installed (I checked).
By forum's reference this is: NTN5833 Smartnet DES (replaced with NTN1072).
I also own T3020BX DES KVL.
I have made such cable:

But nothing works.
What I doing:
1. Turn KVL On;
2. "r E A d Y" message appears;
3. Turn radio On wait for 5 seconds or more;
4. Attach interconnect cable;
5. Press PTT on KVL;
6. After less than 1 sec "FAI.L" message appears on KVL's display :(
When I read radio with RSS "Priority Securnet Detected" message appears in right top corner.
"XL" option in "Channel Definition" is disabled.
All "Radio Feature Options" are turned OFF, including H400 (Secure Voice Slaved to a Mode), H401 (Clear Voice Slaved to a Mode) and H432 (VP Capable-Only).
When ERGO switch in "Secure" position radio makes 7 short beeps in sequence, what means that key not loaded.
If I turn radio On when cable already connected to KVL, radio starts to continuously make pops (pop-pop-pop-pop-pop-pop-pop-pop-pop-pop-pop-pop-pop-pop-pop & etc.).
Any ideas?