diff --git a/internal/platform/plutosdr/pluto_windows.go b/internal/platform/plutosdr/pluto_windows.go
index fa57e3f..eb51e24 100644
--- a/internal/platform/plutosdr/pluto_windows.go
+++ b/internal/platform/plutosdr/pluto_windows.go
@@ -110,6 +110,7 @@ type PlutoDriver struct {
 	phyDev   uintptr // iio_device* (ad9361-phy)
 	chanI    uintptr // iio_channel* TX I
 	chanQ    uintptr // iio_channel* TX Q
+	chanLO   uintptr // iio_channel* TX LO (altvoltage1), cached for Tune()
 	buf      uintptr // iio_buffer*
 	bufSize  int     // samples per buffer push
 
@@ -204,6 +205,7 @@ func (d *PlutoDriver) Configure(_ context.Context, cfg platform.SoapyConfig) err
 
 	// TX LO frequency
 	phyChanLO := d.findChannel(phyDev, "altvoltage1", true) // TX LO
+	d.chanLO = phyChanLO // cache for Tune()
 	if phyChanLO != 0 {
 		freqHz := int64(cfg.CenterFreqHz)
 		if freqHz <= 0 {
@@ -371,14 +373,21 @@ func (d *PlutoDriver) Flush(_ context.Context) error { return nil }
 func (d *PlutoDriver) Tune(_ context.Context, freqHz float64) error {
 	d.mu.Lock()
 	defer d.mu.Unlock()
-	if d.phyDev == 0 {
-		return fmt.Errorf("pluto: not configured")
+	if !d.configured || d.chanLO == 0 {
+		return fmt.Errorf("pluto: not configured or LO channel not available")
+	}
+	if d.lib.pChannelAttrWriteLongLong == nil {
+		return fmt.Errorf("pluto: iio_channel_attr_write_longlong not loaded")
 	}
-	phyChanLO := d.findChannel(d.phyDev, "altvoltage1", true)
-	if phyChanLO == 0 {
-		return fmt.Errorf("pluto: TX LO channel not found")
+	cAttr, _ := syscall.BytePtrFromString("frequency")
+	ret, _, _ := d.lib.pChannelAttrWriteLongLong.Call(
+		d.chanLO,
+		uintptr(unsafe.Pointer(cAttr)),
+		uintptr(int64(freqHz)),
+	)
+	if int32(ret) < 0 {
+		return fmt.Errorf("pluto: LO tune to %.0f Hz failed (iio rc=%d)", freqHz, int32(ret))
 	}
-	d.writeChanAttrLL(phyChanLO, "frequency", int64(freqHz))
 	return nil
 }
 
@@ -420,6 +429,7 @@ func (d *PlutoDriver) cleanup() {
 		d.disableChannel(d.chanQ)
 		d.chanQ = 0
 	}
+	d.chanLO = 0 // config-only channel, no disable needed
 	if d.ctx != 0 && d.lib.pDestroyCtx != nil {
 		d.lib.pDestroyCtx.Call(d.ctx)
 		d.ctx = 0