commented the logic + tidied it up a bit

rotary.py

@@ -1,6 +1,7 @@
 import time
 from pigpio_encoder.rotary import Rotary
 
+# Bands dict
 bands = {
 	"80m":[3.5, 4],
 	"40m":[7, 7.3],
@@ -10,25 +11,33 @@ bands = {
 	"70cm":[430,440]
 }
 
+# iterate over band
 band = iter(bands)
-CURRENT_BAND = next(band)
+CURRENT_BAND = None
 
-def setup_encoder(ranges:list):
+def setup_encoder(ranges:list, scale:float=.25):
+	# make the minimum and maximum deviate by .1
+	minimum, maximum = ranges
+	minimum -= .1
+	maximum += .1
+	
+	# prints current value
 	def rotary_callback(counter):
 		print("Counter value: ", round(counter, 2))
 
 
+	# init rotary
 	my_rotary = Rotary(
 		clk_gpio=17,
 		dt_gpio=27,
 		sw_gpio=22
 	)
 
-
+	# setup rotary
 	my_rotary.setup_rotary(
-		min=ranges[0],
-		max=ranges[1],
-		scale=.25,
+		min=minimum,
+		max=maximum,
+		scale=scale,
 		debounce=300,
 		rotary_callback=rotary_callback
 	)
@@ -39,27 +48,29 @@ def setup_encoder(ranges:list):
 def change_band(plus:bool=False, minus:bool=False):
 	global CURRENT_BAND
 	if plus:
+		# rollover positive next
 		CURRENT_BAND = next(band)
 	if minus:
 		try:
-			CURRENT_BAND = bands[list(bands)[list(bands.keys()).index(CURRENT_BAND)-1]]
+			# rollover negative previous
+			bands_keys = list(bands)
+			CURRENT_BAND = bands[bands_keys[bands_keys.index(CURRENT_BAND)-1]]
 			print(CURRENT_BAND)
-		except Exception as e:
-			print(e)
+		except IndexError:
+			pass
 
+	# new encoder
 	encoder = setup_encoder(bands[CURRENT_BAND])
 	print(CURRENT_BAND)
 	
 	return encoder
 
-encoder = setup_encoder(bands[next(band)])
-
 def main():
-	global encoder
-	while True:
-		if encoder.counter >= encoder.max:
 	encoder = change_band(plus=True)
-		if encoder.counter <= encoder.min:
+	while True:
+		if encoder.counter > bands[CURRENT_BAND][1]:
+			encoder = change_band(plus=True)
+		if encoder.counter < bands[CURRENT_BAND][0]:
 			encoder = change_band(minus=True)
 		time.sleep(.5)