Contained herein are attenuator values for both PI
and TEE types. The need for standard values can
be met by using one or the other. I recommend the
following for a 0 to 147 dB attenuator:
TEE TEE PI TEE TEE PI PI PI
1 2 4 8 12 20 40 60 dB
This configuration will minimize the number of switches
thrown at any one time, thereby improving accuracy.IN O-------+------/\/\/\/\/--------+-------o OUT | | | R2 | / / \ \ / / R1 \ \ R1 / / \ \ | | | | ----- ----- //// //// Precision (PI Atten): +---------+------------+------------+ | Atten. | R1 | R2 | +---------+------------+------------+ | 1 | 886.939 | 5.88457 | | 2 | 444.936 | 11.8472 | | 3 | 298.25 | 17.9671 | | 4 | 225.391 | 24.3254 | | 5 | 182.058 | 31.0064 | | 6 | 153.486 | 38.0989 | | 7 | 133.343 | 45.697 | | 8 | 118.465 | 53.9014 | | 9 | 107.094 | 62.821 | | 10 | 98.1725 | 72.5743 | | 15 | 73.0616 | 138.862 | | 20 | 62.3333 | 252.45 | | 25 | 57.0777 | 452.027 | | 30 | 54.3309 | 805.574 | +---------+------------+------------+ I know these aren't standard values, but I wanted to give precise data. Either Measure to find the closest resistors or try the following as suggestions: Standard values (PI Atten): +---------+------------+------------+ | Atten. | R1 | R2 | +---------+------------+------------+ | 1 | 910 | 6.2 | | 2 | 470 | 12 | | 3 | 300 | 18 | | 5 | 200 | 33 | | 6 | 150 | 39 | | 10 | 100 | 75 | | 20 | 62 | 240 | | 40 | 51 | 2.4K | | 60 | 51 | 24.0K | +-----OR----------------------------+ | 20 | 68 | 270 | +---------+------------+------------+
IN O---/\/\/\/\/---------+------/\/\/\/\/---------o OUT | R2 | R2 / \ / R1 \ / \ | | ----- //// Standard values (TEE Atten): +---------+------------+------------+ | Atten. | R1 | R2 | +---------+------------+------------+ | 1 | 430 | 2.7 | | 2 | 220 | 5.6 | | 8 | 47 | 22 | | 12 | 27 | 30 | +---------+------------+------------+
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