[Elecraft] K3S/ P3 with SPE 1.5KFA

[Samir Popaja]

Hi all,

I'm trying to get CAT communication working between my K3S + P3 setup and
an SPE Expert 1.5K-FA.
Here is my current configuration:

K3S USB → PC (for DXLog CAT control)

K3S RS-232 (RJ45) → P3 using the original Elecraft cable (connected to P3
“XCVR/RS-232”)

>From the P3 “PC/RS-232” port, I made a cable:

P3 pin 3 (TX) → SPE CAT DB-15M pin 1 (RX)

P3 pin 5 (GND) → SPE CAT pin 4 (GND)

My goal is simple: I want the SPE 1.5K-FA to listen for CAT data and
automatically follow band changes from the K3S. I don’t need full two-way
control.

However, the amplifier only reports “CAT Error” and never goes into LSN
state.

Is my wiring wrong, or am I misunderstanding how CAT pass-through works on
the P3?
Any advice from someone who has this setup working would be greatly
appreciated.

73,
Samir (SM7VZX)