View Full Version : -20dB pad values


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.
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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.