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Resistors normally come in standard values with standard tolerances. Through Hole resistors (as well as other components) have for many years used a color code marking scheme to indicate the value and tolerance. The resistor will usually have either four or five colored bands around it to indicate value and tolerance. Generally, the "last" band will indicate tolerance (10%, 5%, 1%, etc.) The "next to last" band will be a multiplier for a power of ten (X1, X10, X100, X .01, etc.) The remaining two or three bands will indicate digits of the value, read left to right. If there are six bands the sixth is temperature coefficient. Here's the color code:
| First | Second | * | Next to last | last | |
| Black | 0 | 0 | 0 | X 1 | |
| Brown | 1 | 1 | 1 | X 10 | 1% |
| Red | 2 | 2 | 2 | X 100 | 2% |
| Orange | 3 | 3 | 3 | X 1K | 3% |
| Yellow | 4 | 4 | 4 | X 10K | 4% |
| Green | 5 | 5 | 5 | X 100K | 0.5% |
| Blue | 6 | 6 | 6 | X 1M | 0.25% |
| Violet | 7 | 7 | 7 | X 10M | 0.1% |
| Gray | 8 | 8 | 8 | X 100M | 0.05% |
| White | 9 | 9 | 9 | X 1G | |
| Gold | Div 10 | 5% | |||
| Silver | Div 100 | 10% |
These are the standard resistor values by tolerance. E12 (12 values per decade) are used for 10%. E24 (24 values) are used for 5% and 2%. E96 (96 values) are used for 1%. E192 (192 values) are used for 0.5%, 0.25%, and 0.1%.
| E192 | E96 | E24 | E12 |
| 10.0 | 10.0 | 10 | 10 |
| 10.1 | -- | -- | -- |
| 10.2 | 10.2 | -- | -- |
| 10.4 | -- | -- | -- |
| 10.5 | 10.5 | -- | -- |
| 10.6 | -- | -- | -- |
| 10.7 | 10.7 | -- | -- |
| 10.9 | -- | -- | -- |
| 11.0 | 11.0 | 11 | -- |
| 11.1 | -- | -- | -- |
| 11.3 | 11.3 | -- | -- |
| 11.4 | -- | -- | -- |
| 11.5 | 11.5 | -- | -- |
| 11.7 | -- | -- | -- |
| 11.8 | 11.8 | -- | -- |
| 12.0 | -- | 12 | 12 |
| 12.1 | 12.1 | -- | -- |
| 12.3 | -- | -- | -- |
| 12.4 | 12.4 | -- | -- |
| 12.6 | -- | -- | -- |
| 12.7 | 12.7 | -- | -- |
| 12.9 | -- | -- | -- |
| 13.0 | 13.0 | 13 | -- |
| 13.2 | -- | -- | -- |
| 13.3 | 13.3 | -- | -- |
| 13.5 | -- | -- | -- |
| 13.7 | 13.7 | -- | -- |
| 13.8 | -- | -- | -- |
| 14.0 | 14.0 | -- | -- |
| 14.2 | -- | -- | -- |
| 14.3 | 14.3 | -- | -- |
| 14.5 | -- | -- | -- |
| 14.7 | 14.7 | -- | -- |
| 14.9 | -- | -- | -- |
| 15.0 | 15.0 | 15 | 15 |
| 15.2 | -- | -- | -- |
| 15.4 | 15.4 | -- | -- |
| 15.6 | -- | -- | -- |
| 15.8 | 15.8 | -- | -- |
| 16.0 | -- | 16 | -- |
| 16.2 | 16.2 | -- | -- |
| 16.4 | -- | -- | -- |
| 16.5 | 16.5 | -- | -- |
| 16.7 | -- | -- | -- |
| 16.9 | 16.9 | -- | -- |
| 17.2 | -- | -- | -- |
| 17.4 | 17.4 | -- | -- |
| 17.6 | -- | -- | -- |
| 17.8 | 17.8 | -- | -- |
| 18.0 | -- | 18 | 18 |
| 18.2 | 18.2 | -- | -- |
| 18.4 | -- | -- | -- |
| 18.7 | 18.7 | -- | -- |
| 18.9 | -- | -- | -- |
| 19.1 | 19.1 | -- | -- |
| 19.3 | -- | -- | -- |
| 19.6 | 19.6 | -- | -- |
| 19.8 | -- | -- | -- |
| 20.0 | 20.0 | 20 | -- |
| 20.3 | -- | -- | -- |
| 20.5 | 20.5 | -- | -- |
| 20.8 | -- | -- | -- |
| 21.0 | 21.0 | -- | -- |
| 21.3 | -- | -- | -- |
| 21.5 | 21.5 | -- | -- |
| 21.8 | -- | -- | -- |
| 22.1 | 22.1 | 22 | 22 |
| 22.3 | -- | -- | -- |
| 22.6 | 22.6 | -- | -- |
| 22.9 | -- | -- | -- |
| 23.2 | 23.2 | -- | -- |
| 23.4 | -- | -- | -- |
| 23.7 | 23.7 | -- | -- |
| 24.0 | -- | 24 | -- |
| 24.3 | 24.3 | -- | -- |
| 24.6 | -- | -- | -- |
| 24.9 | 24.9 | -- | -- |
| 25.2 | -- | -- | -- |
| 25.5 | 25.5 | -- | -- |
| 25.8 | -- | -- | -- |
| 26.1 | 26.1 | -- | -- |
| 26.4 | -- | -- | -- |
| 26.7 | 26.7 | 27 | 27 |
| 27.1 | -- | -- | -- |
| 27.4 | 27.4 | -- | -- |
| 27.7 | -- | -- | -- |
| 28.0 | 28.0 | -- | -- |
| 28.4 | -- | -- | -- |
| 28.7 | 28.7 | -- | -- |
| 29.1 | -- | -- | -- |
| 30.1 | 30.1 | 30 | -- |
| 30.5 | -- | -- | -- |
| 30.9 | 30.9 | -- | -- |
| 31.2 | -- | -- | -- |
| 31.6 | 31.6 | -- | -- |
| 32.0 | -- | -- | -- |
| 32.4 | 32.4 | -- | -- |
| 32.8 | -- | -- | -- |
| 33.2 | 33.2 | 33 | 33 |
| 33.6 | -- | -- | -- |
| 34.0 | 34.0 | -- | -- |
| 34.4 | -- | -- | -- |
| 34.8 | 34.8 | -- | -- |
| 35.2 | -- | -- | -- |
| 35.7 | 35.7 | -- | -- |
| 36.1 | -- | 36 | -- |
| 36.5 | 36.5 | -- | -- |
| 37.0 | -- | -- | -- |
| 37.4 | 37.4 | -- | -- |
| 37.9 | -- | -- | -- |
| 38.3 | 38.3 | -- | -- |
| 38.8 | -- | -- | -- |
| 39.2 | 39.2 | 39 | 39 |
| 39.7 | -- | -- | -- |
| 40.2 | 40.2 | -- | -- |
| 40.7 | -- | -- | -- |
| 41.2 | 41.2 | -- | -- |
| 41.7 | -- | -- | -- |
| 42.2 | 42.2 | -- | -- |
| 42.7 | -- | -- | -- |
| 43.2 | 43.2 | 43 | -- |
| 43.7 | -- | -- | -- |
| 44.2 | 44.2 | -- | -- |
| 44.8 | -- | -- | -- |
| 45.3 | 45.3 | -- | -- |
| 45.9 | -- | -- | -- |
| 46.4 | 46.4 | -- | -- |
| 47.0 | -- | 47 | 47 |
| 47.5 | 47.5 | -- | -- |
| 48.1 | -- | -- | -- |
| 48.7 | 48.7 | -- | -- |
| 49.3 | -- | -- | -- |
| 49.9 | 49.9 | -- | -- |
| 50.5 | -- | -- | -- |
| 51.1 | 51.1 | 51 | -- |
| 51.7 | -- | -- | -- |
| 52.3 | 52.3 | -- | -- |
| 53.0 | -- | -- | -- |
| 53.6 | 53.6 | -- | -- |
| 54.2 | -- | -- | -- |
| 54.9 | 54.9 | -- | -- |
| 55.6 | -- | -- | -- |
| 56.2 | 56.2 | 56 | 56 |
| 56.9 | -- | -- | -- |
| 57.6 | 57.6 | -- | -- |
| 58.3 | -- | -- | -- |
| 59.0 | 59.0 | -- | -- |
| 59.7 | -- | -- | -- |
| 60.4 | 60.4 | -- | -- |
| 61.2 | -- | -- | -- |
| 61.9 | 61.9 | -- | -- |
| 62.6 | -- | 62 | -- |
| 63.4 | 63.4 | -- | -- |
| 64.2 | -- | -- | -- |
| 64.9 | 64.9 | -- | -- |
| 65.7 | -- | -- | -- |
| 66.5 | 66.5 | -- | -- |
| 67.3 | -- | -- | -- |
| 68.1 | 68.1 | 68 | 68 |
| 69.0 | -- | -- | -- |
| 69.8 | 69.8 | -- | -- |
| 70.6 | -- | -- | -- |
| 71.5 | 71.5 | -- | -- |
| 72.3 | -- | -- | -- |
| 73.2 | 73.2 | -- | -- |
| 74.1 | -- | -- | -- |
| 75.0 | 75.0 | 75 | -- |
| 75.9 | -- | -- | -- |
| 76.8 | 76.8 | -- | -- |
| 77.7 | -- | -- | -- |
| 78.7 | 78.7 | -- | -- |
| 79.6 | -- | -- | -- |
| 80.6 | 80.6 | -- | -- |
| 81.6 | -- | -- | -- |
| 82.5 | 82.5 | 82 | 82 |
| 83.5 | -- | -- | -- |
| 84.5 | 84.5 | -- | -- |
| 85.6 | -- | -- | -- |
| 86.6 | 86.6 | -- | -- |
| 87.6 | -- | -- | -- |
| 88.7 | 88.7 | -- | -- |
| 89.8 | -- | -- | -- |
| 90.9 | 90.9 | -- | -- |
| 92.0 | -- | 91 | -- |
| 93.1 | 93.1 | -- | -- |
| 94.2 | -- | -- | -- |
| 95.3 | 95.3 | -- | -- |
| 96.5 | -- | -- | -- |
| 97.6 | 97.6 | -- | -- |
| 98.8 | -- | -- | -- |
Here is some basic wire information:
| AWG | Dia(mils) | cmils | TPI | Icont open | Icont bundle | ft/lb | Ohms/1000' | Icont 700cm/A | dia mm | British |
| 1 | 289.3 | 83690 | na | n/a | n/a | 3.947 | .1264 | 119.6 | 7.348 | 1 |
| 2 | 257.6 | 66370 | na | n/a> | n/a | 4.977 | .1593 | 94.8 | 6.544 | 3 |
| 3 | 229.4 | 52640 | na | na | na | 6.275 | .2009 | 75.2 | 5.827 | 4 |
| 4 | 204.3 | 41740 | na | na | na | 7.914 | .2533 | 59.6 | 5.189 | 5 |
| 5 | 181.9 | 33100 | na | na | na | 9.980 | .3195 | 47.3 | 4.621 | 7 |
| 6 | 162.0 | 26250 | na | na | na | 12.58 | .4028 | 37.5 | 4.115 | 8 |
| 7 | 144.3 | 20820 | na | na | na | 15.87 | .5080 | 29.7 | 3.665 | 9 |
| 8 | 128.5 | 16510 | 7.6 | 73 | 46 | 20.01 | .6405 | 23.6 | 3.264 | 10 |
| 9 | 114.4 | 13090 | 8.6 | na | na | 25.23 | .8077 | 18.7 | 2.906 | 11 |
| 10 | 101.9 | 10380 | 9.6 | 55 | 33 | 31.82 | 1.018 | 14.8 | 2.588 | 12 |
| 11 | 90.7 | 8234 | 10.7 | n/a | n/a | 40.12 | 1.284 | 11.8 | 2.305 | 13 |
| 12 | 80.8 | 6350 | 12 | 41 | 23 | 50.59 | 1.619 | 9.33 | 2.053 | 14 |
| 13 | 72 | 5178 | 13.5 | n/a | n/a | 63.80 | 2.042 | 7.4 | 1.828 | 15 |
| 14 | 64.1 | 4107 | 15 | 32 | 17 | 80.44 | 2.575 | 5.87 | 1.628 | 16 |
| 15 | 57.1 | 3257 | 16.8 | n/a | n/a | 101.4 | 3.247 | 4.65 | 1.450 | 17 |
| 16 | 50.8 | 2583 | 18.9 | 22 | 13 | 127.9 | 4.094 | 3.69 | 1.291 | 18 |
| 17 | 45.3 | 2048 | 21.2 | na | na | 161.3 | 5.163 | 2.93 | 1.150 | 18 |
| 18 | 40.3 | 1624 | 23.6 | 16 | 10 | 203.4 | 6.510 | 2.32 | 1.024 | 19 |
| 19 | 35.9 | 1288 | 26.4 | na | na | 256.5 | 8.210 | 1.84 | .912 | 20 |
| 20 | 32 | 1022 | 29.4 | 11 | 7.5 | 323.4 | 10.35 | 1.46 | .812 | 21 |
| 21 | 28.5 | 810 | 33.1 | na | na | 407.8 | 13.05 | 1.16 | .723 | 22 |
| 22 | 25.3 | 642 | 37 | na | 5 | 514.2 | 16.46 | .918 | .644 | 23 |
| 23 | 22.6 | 510 | 41.3 | na | na | 648.4 | 20.76 | .728 | .573 | 24 |
| 24 | 20.1 | 404 | 46.3 | na | na | 817.7 | 26.17 | .577 | .511 | 25 |
| 25 | 17.9 | 320 | 51.7 | na | na | 1031 | 33.00 | .458 | .455 | 26 |
| 26 | 15.9 | 254 | 58.0 | na | na | 1300 | 41.62 | .363 | .405 | 27 |
| 27 | 14.2 | 202 | 64.9 | na | na | 1639 | 52.48 | .288 | .361 | 29 |
| 28 | 12.6 | 160 | 72.7 | na | na | 2067 | 66.17 | .228 | .321 | 30 |
| 29 | 11,3 | 127 | 81.6 | na | na | 2607 | 83.44 | .181 | .286 | 31 |
| 30 | 10.0 | 101 | 90.5 | na | na | 3287 | 105.2 | .144 | .255 | 33 |
| 31 | 8.9 | 80 | 101 | na | na | 4145 | 132.7 | .114 | .227 | 34 |
| 32 | 8.0 | 63 | 113 | na | na | 5227 | 167.3 | .090 | .202 | 36 |
| 33 | 7.1 | 50 | 127 | na | na | 6591 | 211.0 | .072 | .180 | 37 |
| 34 | 6.3 | 40 | 143 | na | na | 8310 | 266.0 | .057 | .160 | 38 |
| 35 | 5.6 | 32 | 158 | na | na | 10480 | 335.0 | .045 | .143 | 38/39 |
| 36 | 5.0 | 25 | 175 | na | na | 13210 | 423.0 | .036 | .127 | 39/40 |
| 37 | 4.5 | 20 | 198 | na | na | 16660 | 533.0 | .028 | .113 | 41 |
| 38 | 4.0 | 16 | 224 | na | na | 21010 | 673.0 | .022 | .101 | 42 |
| 39 | 3.5 | 12 | 248 | na | na | 26500 | 848.0 | .018 | .090 | 43 |
| 40 | 3.1 | 10 | 282 | na | na | 33410 | 1070 | .014 | .080 | 44 |
The toroid table below gives important information on toroid cores available from Amidon Associates. For many of the cores I got the information from toroids.info . Those are marked with an asterisk "*". That site has a REALLY handy calculator to find the turns needed for some specific inductance as well as various other useful information for all the cores they list. It is hosted by Kits and Parts which is a very nice company to deal with in my experience. Their site is much better AND they will sell you the parts!
NOTE: All the Al values listed here are used with the formula:
uH = (Al * Turns^2) / 1000
which is NOT the formula typically given for powdered iron.
To calculate turns needed with all these Al values, use
Turns = sqrt( 1000 * uH / Al)
| Toroid | OD | ID | Ht | AL | TempCo | Color | Freq | ||
| * T37-0 | .375 | .205 | .128 | .49 | 0 | Tan/Tan | 50 MHz - 350 MHz | ||
| * T106-0 | 1.06 | .570 | .437 | 1.9 | 0 | Tan/Tan | 50 MHz - 350 MHz | ||
| * T130-0 | 1.30 | .780 | .437 | 1.5 | 0 | Tan/Tan | 50 MHz - 350 MHz | ||
| * T37-1 | .375 | .205 | .128 | 8 | 280 | Blu/Clr | 150 KHz - 3 MHz | ||
| * T50-1 | .500 | .303 | .190 | 10 | 280 | Blu/Clr | 150 KHz - 3 MHz | ||
| * T68-1 | .690 | .370 | .190 | 11.5 | 280 | Blu/Clr | 150 KHz - 3 MHz | ||
| * T130-1 | 1.30 | .780 | .437 | 20.0 | 280 | Blu/Clr | 150 KHz - 3 MHz | ||
| * T25-2 | .250 | .120 | .096 | 3.4 | 95 | Red/Clr | 250KHz - 10 MHz | ||
| * T30-2 | .307 | .151 | .128 | 4.3 | 95 | Red/Clr | 250KHz - 10 MHz | ||
| * T37-2 | .375 | .205 | .128 | 4.0 | 95 | Red/Clr | 250KHz-10MHz | ||
| * T44-2 | .440 | .229 | .159 | 5.2 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T50-2 | .500 | .303 | .190 | 4.9 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T68-2 | .690 | .370 | .190 | 5.7 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T80-2 | .795 | .495 | .250 | 5.5 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T94-2 | .942 | .560 | .312 | 8.4 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T106-2 | 1.06 | .570 | .437 | 13.5 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T130-2 | 1.30 | .780 | .437 | 11.0 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T157-2 | 1.57 | .950 | .570 | 14.0 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T200-2 | 2.00 | 1.25 | .550 | 12.0 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T225-2B | 2.25 | 1.40 | 1.00 | 21.5 | 95 | Red/Clr | 250 KHz - 10 MHz | ||
| * T50-3 | .500 | .303 | .190 | 17.5 | 370 | Gry/Clr | 20 KHz - 1 MHz | ||
| * T25-6 | .255 | .120 | .096 | 2.7 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T30-6 | .307 | .151 | .128 | 3.6 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T37-6 | .375 | .205 | .128 | 3.0 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T44-6 | .440 | .229 | .159 | 4.2 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T50-6 | .500 | .303 | .190 | 4.0 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T68-6 | .690 | .370 | .190 | 4.7 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T80-6 | .795 | .495 | .250 | 4.5 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T94-6 | .942 | .560 | .312 | 7.0 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T106-6 | 1.06 | .570 | .437 | 11.6 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T130-6 | 1.30 | .780 | .437 | 9.6 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T200-6 | 2.00 | 1.25 | .550 | 10.4 | 35 | Ylw/Clr | 3 MHz - 40 MHz | ||
| * T37-7 | .375 | .205 | .128 | 3.2 | 30 | Wht/Clr | 1 MHz - 25 MHz | ||
| * T50-7 | .500 | .303 | .190 | 4.3 | 30 | Wht/Clr | 1 MHz - 25 MHz | ||
| * T68-7 | .690 | .370 | .190 | 5.2 | 30 | Wht/Clr | 1 MHz - 25 MHz | ||
| * T30-10 | .307 | .151 | .128 | 2.5 | 150 | Blk/Clr | 15 MHz - 100 MHz | ||
| * T37-10 | .375 | .205 | .128 | 2.5 | 150 | Blk/Clr | 15 MHz - 100 MHz | ||
| * T50-10 | .500 | .303 | .190 | 3.1 | 150 | Blk/Clr | 15 MHz - 100 MHz | ||
| * T68-10 | .690 | .370 | .190 | 3.2 | 150 | Blk/Clr | 15 MHz - 100 MHz | ||
| * T80-10 | .795 | .495 | .250 | 3.2 | 150 | Blk/Clr | 15 MHz - 100 MHz | ||
| * T94-10 | .942 | .560 | .312 | 5.8 | 150 | Blk/Clr | 15 MHz - 100 MHz | ||
| * T37-17 | .375 | .205 | .128 | 1.5 | 50 | Blu/Ylw | 20 MHz - 200 MHz | ||
| * T50-17 | .500 | .303 | .190 | 1.8 | 50 | Blu/Ylw | 20 MHz - 200 MHz | ||
| * T80-17 | .795 | .495 | .250 | 2.2 | 50 | Blu/Ylw | 20 MHz - 200 MHz | ||
| * T130-17 | 1.30 | .780 | .437 | 4.0 | 50 | Blu/Ylw | 20 MHz - 200 MHz | ||
| * T157-17 | 1.57 | .950 | .570 | 5.3 | 50 | Blu/Ylw | 20 MHz - 200 MHz | ||
| * T184-17 | 1.84 | .950 | .710 | 8.7 | 50 | Blu/Ylw | 20 MHz - 200 MHz | ||
| T16-26 | 14.5 | Yel/Whit | Power freq | ||||||
| T20-26 | 18.0 | Yel/Wht | Power freq | ||||||
| T25-26 | 23.5 | Yel/Wht | Power freq | ||||||
| T30-26 | 32.5 | Yel/Wht | Power freq | ||||||
| T37-26 | 27.5 | Yel/Wht | Power freq | ||||||
| T44-26 | 36.0 | Yel/Wht | Power freq | ||||||
| T50-26 | 32.0 | Yel/Wht | Power freq | ||||||
| T68-26 | 42.0 | Yel/Wht | Power freq | ||||||
| T80-26 | 45.0 | Yel/Wht | Power freq | ||||||
| T94-26 | 59.0 | Yel/Wht | Power freq | ||||||
| T106-26 | 90.0 | Yel/Wht | Power freq | ||||||
| T130-26 | 78.5 | Yel/Wht | Power freq | ||||||
| T157-26 | 97.0 | Yel/Wht | Power freq | ||||||
| T184-26 | 164 | Yel/Wht | Power freq | ||||||
| T200-26 | 89.5 | Yel/Wht | Power freq | ||||||
| T200A-26 | 2.00 | 1.25 | 1.00 | 155 | Yel/Wht | Power freq | |||
| T225-26 | 2.25 | 1.405 | .550 | 95.0 | Yel/Wht | Power freq | |||
| T225A-26 | 2.25 | 1.485 | 1.00 | 160 | Yel/Wht | Power freq | |||
| T300-26 | 3.06 | 1.925 | .500 | 80.0 | Yel/Wht | Power freq | |||
| T300A-26 | 3.048 | 1.925 | 1.00 | 160 | Yel/Wht | Power freq | |||
| Ferrite | OD | ID | Ht | AL | TempCo | Color | Wideband Xfmr | Power Xfmr | RFI suppresion |
| * FT240-31 | 2.40 | 1.40 | .500 | 3180 | 16000 | Black | 1 MHz - 300 MHz | .5 MHz - 30 MHz | 1 MHz - 500 MHz |
| * FT23-43 | .230 | .120 | .060 | 158 | 12500 | shny Blk | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT37-43 | .375 | .187 | .125 | 350 | 12500 | shny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT50-43 | .500 | .281 | .188 | 440 | 12500 | shiny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT82-43 | .825 | .520 | .250 | 470 | 12500 | shiny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT114-43 | 1.14 | .748 | .295 | 510 | 12500 | shiny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT140-43 | 1.40 | .900 | .500 | 885 | 12500 | shiny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT240-43 | 2.40 | 1.40 | .500 | 1075 | 12500 | shiny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| * FT290-43 | 2.90 | 1.53 | .500 | 1275 | 12500 | shiny Black | 5 MHz - 400 MHz | .5 MHz - 30 MHz | 5 MHz - 500 MHz |
| Toroid | OD | ID | Ht | AL | TempCo | Color | Wideband Xfmr | High Q inductor | RFI Suppression |
| * FT240-52 | 2.40 | 1.40 | .500 | 330 | 2000 | dl Blk | 10 MHz - 500 MHz | .1 MHz - 5 MHz | Above 10 MHz |
| * FT37-61 | .375 | .187 | .125 | 55 | 1000 | dl Blk | 20 MHz - 500 MHz | .2 MHz - 10 MHz | Above 20 MHz |
| * FT50-61 | .500 | .281 | .188 | 69 | 1000 | dl Blk | 20 MHz - 500 MHz | .2 MHz - 10 MHz | Above 20 MHz |
| * FT114-61 | 1.14 | .748 | .295 | 75 | 1000 | dl Blk | 20 MHz - 500 MHz | .2 MHz - 10 MHz | Above 20 MHz |
| * FT140-61 | 1.40 | .900 | .500 | 150 | 1000 | dl Blk | 20 MHz - 500 MHz | .2 MHz - 10 MHz | Above 20 MHz |
| * FT240-61 | 2.40 | 1.40 | .500 | 170 | 1000 | dl Blk | 20 MHz - 500 MHz | .2 MHz - 10 MHz | Above 20 MHz |
| * FT37-67 | .375 | .187 | .125 | 20 | 500 | dl Blk | 50 MHz - 1000 MHz | .5 MHz - 30 MHz | Above 50 MHz |
| Toroid | OD | ID | Ht | AL | TempCo | Color | Wideband Xfmr | Power Xfmer | RFI Suppression |
| * FT50-75 | .500 | .281 | .188 | 4200 | 6000 | shy blk | 1 MHz - 50 MHz | .1 MHz - 3 MHz | Above 1 MHz |
Below is a table of resistor values for various attenuations for either PI or Tee type attenuaators
with 50 Ohm in/out impedances. This table is from 1984 ARRL Radio Amateur's Handbook. If you need
to calculate your own values for some reason, or just want to know, here are the formulas for the
resistor values:
Pi (from Pasternack
Rseries = Z0 * [ (10^(Adb/20) + 1) / (10^(Adb/20) -1) ]
Rshunt = Z0/2 * [ 10^(Adb/20) - 1/(10^(Adb/20)) ]
Tee (from Pasternack
Rseries = Z0 * [ (10^(Adb/20)-1) / (10^(Adb/20)+1)]
Rshunt = 2Z0 * [ (10^(Adb/20) / (10^(Adb/10) - 1)]
To adapt the values for other impedance levels (Z), multiply all values by Z/50.
| Attenuation | Pi | T | ||
| Series | Shunt | Series | Shunt | |
| 1 db | 5.8 | 870.0 | 2.9 | 433.3 |
| 2 db | 11.6 | 436.0 | 5.7 | 215.2 |
| 3 db | 17.6 | 292.0 | 8.5 | 141.9 |
| 4 db | 23.8 | 221.0 | 11.3 | 104.8 |
| 5 db | 30.4 | 178.6 | 14.0 | 82.2 |
| 6 db | 37.3 | 150.5 | 16.6 | 66.9 |
| 7 db | 44.8 | 130.7 | 19.0 | 55.8 |
| 8 db | 52.8 | 116.0 | 21.5 | 47.3 |
| 9 db | 61.6 | 105.0 | 23.8 | 40.6 |
| 10 db | 71.2 | 96.2 | 26.0 | 35.0 |
| 11 db | 81.6 | 89.2 | 28.0 | 30.6 |
| 12 db | 93.2 | 83.5 | 30.0 | 26.8 |
| 13 db | 106.0 | 78.8 | 31.7 | 23.5 |
| 14 db | 120.3 | 74.9 | 33.3 | 20.8 |
| 15 db | 136.1 | 71.6 | 35.0 | 18.4 |
| 16 db | 153.8 | 68.8 | 36.3 | 16.2 |
| 17 db | 173.4 | 66.4 | 37.6 | 14.4 |
| 18 db | 195.4 | 64.4 | 38.8 | 12.8 |
| 19 db | 220.0 | 62.6 | 40.0 | 11.4 |
| 20 db | 247.5 | 61.0 | 41.0 | 10.0 |
| 21 db | 278.2 | 59.7 | 41.8 | 9.0 |
| 22 db | 312.7 | 58.6 | 42.6 | 8.0 |
| 23 db | 351.9 | 57.6 | 43.4 | 7.1 |
| 24 db | 394.6 | 56.7 | 44.0 | 6.3 |
| 25 db | 443.1 | 56.0 | 44.7 | 5.6 |
| 30 db | 789.7 | 53.2 | 47.0 | 3.2 |
| 35 db | 1405.4 | 51.8 | 48.2 | 1.8 |
| 40 db | 2500.0 | 51.0 | 49.0 | 1.0 |
| 45 db | 4446.0 | 50.5 | 49.4 | 0.56 |
| 50 db | 7905.6 | 50.3 | 49.7 | 0.32 |
| 55 db | 14058.0 | 50.2 | 49.8 | 0.18 |
| 60 db | 25000.0 | 50.1 | 49.9 | 0.10 |
Hammond Mfg. type / style case dimensions. These cases are made by Hammond Manufacturing. They are very nice enclosures and not very expensive. Clones are also available, even cheaper, from Tayda Electronics.
| Type | Width(mm/in) | Length(mm/in) | Height(mm/in) |
| 125B | 66 / 2.60 | 122 / 4.80 | 39.5 / 1.56 |
| 1032L | 70 / 2.76 | 253 / 9.96 | 52.2 / 2.06 |
| 1590A | 38 / 1.50 | 92 / 3.62 | 30 / 1.18 |
| 1590B | 60 / 2.36 | 112 / 4.41 | 31 / 1.22 |
| 1590BB | 94 / 3.70 | 120 / 4.72 | 33 / 1.30 |
| 1590BB2 | 94 / 3.70 | 120 / 4.72 | 38 / 1.50 |
| 1590DD | 119 / 4.69 | 188 / 7.40 | 37.5 / 1.48 |
| 1590LB | 50.5 / 1.99 | 50.5 / 1.99 | 31 / 1.22 |
| 1590XX | 121 4.76 | 145 / 5.71 | 39.5 / 1.56 |
under construction...