diff --git a/sodetlib/operations/uxm_setup.py b/sodetlib/operations/uxm_setup.py
index 879b275..7191a49 100644
--- a/sodetlib/operations/uxm_setup.py
+++ b/sodetlib/operations/uxm_setup.py
@@ -442,7 +442,6 @@ def setup_fixed_tones(S, cfg, fixed_tones_per_band=8, min_fixed_tone_spacing=10,
     # TODO check we have a tune?
     ft_freq = []
     for b in S.bands:
-        min_chan_spacing = None  # convert from frequency to channel
         ft_freq += _find_fixed_tone_freq(S, b, fixed_tones_per_band, min_fixed_tone_spacing)
 
     # set the fixed tones