diff --git a/TNC/M17Demodulator.cpp b/TNC/M17Demodulator.cpp
index a6670af..3be14a4 100644
--- a/TNC/M17Demodulator.cpp
+++ b/TNC/M17Demodulator.cpp
@@ -43,7 +43,7 @@ static float dc_block(float x)
 
 void M17Demodulator::start()
 {
-    SysClock72();
+    SysClock48();
 #if defined(HAVE_LSCO)
     HAL_RCCEx_DisableLSCO();
 #endif
@@ -71,7 +71,7 @@ void M17Demodulator::start()
     if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
         CxxErrorHandler();
 
-    startADC(1499, ADC_BLOCK_SIZE);
+    startADC(999, ADC_BLOCK_SIZE);
 //    getModulator().start_loopback();
     dcd_off();
 }
diff --git a/TNC/M17Modulator.cpp b/TNC/M17Modulator.cpp
index de8cc49..039e7cf 100644
--- a/TNC/M17Modulator.cpp
+++ b/TNC/M17Modulator.cpp
@@ -11,10 +11,10 @@ void M17Modulator::init(const kiss::Hardware& hw)
 
     (void) hw; // unused
 
-    SysClock72();
+    SysClock48();
 
     // Configure 72MHz clock for 48kHz.
-    htim7.Init.Period = 1499;
+    htim7.Init.Period = 999;
     htim7.Init.Prescaler = 0;
     if (HAL_TIM_Base_Init(&htim7) != HAL_OK)
     {