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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