-20dB pad values at DVinfo.net

Rick Reineke · November 3rd, 2009, 06:10 PM

I need to construct a simple 'L' pad within a special connection cable. The primary is unbalanced at about 0dBu nominally. Can someone tell me what the R1 & R2 values should be to get approx. 20-25db of attenuation. Unbalanced to unbalanced. Thanks.

Bill Wilson · November 4th, 2009, 11:19 AM

20 dbv = a gain of 10. You want to have 1000 ohms as R1 & 100 ohms as R2. The resistors should be 1/4 watt 5% tolerance; these are carbon film resistors. You might see if your local radio shack still carries resistors.

signal in __1000________ Signal out.

100

ground

The 1000 ohm resistor is in series with the incoming signal; the 100 ohm goes from the secondary side of the 1000 ohm resistor to ground. This will give you a 2o db loss in signal voltage.

Rick Reineke · November 4th, 2009, 12:07 PM

Thanks Bill,
I've built many pads, I just can't seem to figure out the resistor value equations. Duh.
-----------------
I had a 1k and 100 ohm in my collection of odds & ends already so a trip to the Shack O' Shame was unnecessary. Soldered them in.. works great. Thanks again.

Bill Wilson · November 5th, 2009, 11:39 AM

Hi Rick: Glad to hear it worked out for you.

Bill W.

November 3rd, 2009, 06:10 PM	#1
Rick Reineke Inner Circle Join Date: Aug 2008 Location: New York Posts: 2,038	-20dB pad values I need to construct a simple 'L' pad within a special connection cable. The primary is unbalanced at about 0dBu nominally. Can someone tell me what the R1 & R2 values should be to get approx. 20-25db of attenuation. Unbalanced to unbalanced. Thanks.

November 4th, 2009, 11:19 AM	#2
Bill Wilson Regular Crew Join Date: Mar 2006 Location: Leesburg, Fla Posts: 86	20db Pad 20 dbv = a gain of 10. You want to have 1000 ohms as R1 & 100 ohms as R2. The resistors should be 1/4 watt 5% tolerance; these are carbon film resistors. You might see if your local radio shack still carries resistors. signal in __1000________ Signal out. 100 ground The 1000 ohm resistor is in series with the incoming signal; the 100 ohm goes from the secondary side of the 1000 ohm resistor to ground. This will give you a 2o db loss in signal voltage.

November 4th, 2009, 12:07 PM	#3
Rick Reineke Inner Circle Join Date: Aug 2008 Location: New York Posts: 2,038	Thanks Bill, I've built many pads, I just can't seem to figure out the resistor value equations. Duh. ----------------- I had a 1k and 100 ohm in my collection of odds & ends already so a trip to the Shack O' Shame was unnecessary. Soldered them in.. works great. Thanks again. Last edited by Rick Reineke; November 4th, 2009 at 03:59 PM. Reason: Addendum

November 5th, 2009, 11:39 AM	#4
Bill Wilson Regular Crew Join Date: Mar 2006 Location: Leesburg, Fla Posts: 86	20 DB Pad Hi Rick: Glad to hear it worked out for you. Bill W.