General discussion area for tube amps. 
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								Cathode Ray 							 
									
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								by Cathode Ray   »  Thu Apr 27, 2023 1:46 am 
			
			
			
			
			What does the circle in this RFI filter schematic represent ?
Thanks in advance !
 
			
			
									
									
						 
		 
				
		
		 
	 
				
		
		
			
				
																			
								TUBEDUDE 							 
									
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								by TUBEDUDE   »  Thu Apr 27, 2023 2:41 am 
			
			
			
			
			An iron toroid? 
I'll take I don't know for a thousand Alex.
			
			
									
									Tube junkie that aspires to become a tri-state bidirectional buss driver.
						 
		 
				
		
		 
	 
				
		
		
			
				
								martin manning 							 
									
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								by martin manning   »  Thu Apr 27, 2023 3:14 am 
			
			
			
			
			It’s a common mode choke, I believe.
			
			
									
									
						 
		 
				
		
		 
	 
				
		
		
			
				
								Cathode Ray 							 
									
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								by Cathode Ray   »  Thu Apr 27, 2023 3:26 am 
			
			
			
			
			Also finding it represented like this:
 
			
			
									
									
						 
		 
				
		
		 
	 
				
		
		
			
				
																			
								Stevem 							 
									
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								by Stevem   »  Thu Apr 27, 2023 10:29 am 
			
			
			
			
			That's a  type  with core trim adjustment screw.
			
			
									
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								TUBEDUDE 							 
									
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								by TUBEDUDE   »  Thu Apr 27, 2023 10:39 am 
			
			
			
			
			Stevem  wrote: ↑ Thu Apr 27, 2023 10:29 am 
That's a  type  with core trim adjustment screw.
Like a powdered iron slug in an IF coil?
Is it to change value or balance the two lines?
I don't think I've seen one. Is it physically like an A.C. power filter with an adjustment?
 
			
			
									
									Tube junkie that aspires to become a tri-state bidirectional buss driver.
						 
		 
				
		
		 
	 
				
		
		
			
				
								Reeltarded 							 
									
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								by Reeltarded   »  Thu Apr 27, 2023 10:49 am 
			
			
			
			
			Variable inductor. There are a bunch of different types.
			
			
									
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