diff --git a/internal/cat/icomnet.go b/internal/cat/icomnet.go
index 5f79529..958a17c 100644
--- a/internal/cat/icomnet.go
+++ b/internal/cat/icomnet.go
@@ -510,7 +510,23 @@ func (n *icomNet) civPump() {
 			debugLog.Printf("icom net: the reopen did not bring CI-V back — forcing a fresh session")
 		}
 		if time.Since(lastIdle) > 150*time.Millisecond {
-			_, _ = n.civ.Write(icnCtrl(0x00, 0, n.vID, n.vRemote))
+			// Idles carry a REAL sequence number, drawn from the same counter as
+			// the data packets, and sit in the retransmit buffer like them —
+			// which is how RS-BA1 and wfview number theirs. Ours used seq 0 on
+			// every idle, seven a second, interleaved with properly-numbered
+			// data; a rig that follows the sequence tolerates that for a minute
+			// or so and then stops serving CI-V data on the stream — which is
+			// the shape of every dropout this loaner IC-7760 has shown, with
+			// the scope and the TX path both since eliminated.
+			n.seqMu.Lock()
+			iseq := n.vTracked
+			n.vTracked++
+			n.seqMu.Unlock()
+			ipkt := icnCtrl(0x00, iseq, n.vID, n.vRemote)
+			n.sentMu.Lock()
+			n.sentBuf[iseq] = ipkt
+			n.sentMu.Unlock()
+			_, _ = n.civ.Write(ipkt)
 			lastIdle = time.Now()
 		}
 		if time.Since(lastReq) > 100*time.Millisecond {