so ive been messing with Winlink Express for about three weeks now and i cant get a full session to complete without it cutting out. running a KAM XL connected to an IC-7300, the frequency is solid, im hearing the pactor handshake start up fine and it even shows connecting to the RMS but then somewhere around 60-70% of the message transfer it just drops. tried two different gateways, same result roughly the same point in the transfer each time.

my RF levels look okay, im not seeing the ALC light up crazy or anything, and the audio into the TNC is sitting around where it should be. did a cable check, everything's tight. i wonder if its a timing issue with the TNC config or maybe something in Winlink Express settings i havent touched yet. the default session timeout maybe? not sure where to even start digging honestly.

anyone run into this kind of consistent dropout at the same percentage point? it almost seems like its triggered by something in the message itself or maybe the handshake response isnt coming back fast enough. running Pactor 2 right now, dont have the P3/P4 license for the KAM.

that percentage-point dropout thing is actually a pretty classic symptom with Pactor 2 and longer messages -- what size are the messages you're trying to send? if they're over maybe 3-4k bytes you can sometimes hit an ARQ timeout issue especially if propagation is even slightly marginal. the protocol is doing all its error correction and if the gateway response latency ticks up even a little the session just gives up.

first thing i'd try is bumping down your audio drive a little more than you think you need to. the IC-7300 ALC can look fine on the panel but still be pushing the TNC input into a region it doesn't love. also check your COM port settings in Winlink Express, specifically the RTS/CTS handshaking -- ive seen that bite people with the KAM when the timing gets out of sync mid-transfer. also worth trying a gateway thats geographically closer to you if possible, the ones with lower path loss will have better ARQ throughput. what part of the country are you in, there might be a P2 gateway with better coverage for your area.

yeah i had almost this exact thing happen when i first set mine up, turned out my USB audio latency was the culprit -- had a cheap USB sound card in the loop and it was introducing enough jitter that the pactor session would go sideways on anything longer than a short test message. switched to the built in audio path on the 7300 via the USB connection and it sorted itself out almost immediately.

not saying thats definitely your problem but worth ruling out if you have any extra audio interfaces in the chain.