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20210714 latest update

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%
There are various mnemonic saying around to remember the colors. The one I learned says something about bad boys and what they do to young girls. It's no longer socially acceptable, so I won't put it here.

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 -- -- --
This is the resistor color code:
Bad Black Boys Brown Rape Red 2 Our Orange 3 Young Yellow 4 Girls Green 5 But Blue 6 Violet Violet 7 Gives Gray 8 Willingly White 9

Here is some basic wire information:
AWGDia(mils)cmilsTPIIcont openIcont bundleft/lb Ohms/1000'Icont 700cm/Adia mmBritish
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 nana 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 33100na 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 165107.6 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 103809.6 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 13.5n/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 128826.4 na na 256.5 8.210 1.84 .912 20
20 32 102229.4 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 64237 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 32051.7 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 16072.7 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 80101 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 40143 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 20198 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 10282 na na 33410 1070 .014 .080 44

Toroid Winding Information

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 TempCoColorFreq
* T37-0 .375 .205 .128 .49 0 Tan/Tan50 MHz - 350 MHz
* T106-0 1.06 .570 .437 1.9 0 Tan/Tan50 MHz - 350 MHz
* T130-0 1.30 .780 .437 1.5 0 Tan/Tan50 MHz - 350 MHz
* T37-1 .375 .205 .128 8 280 Blu/Clr150 KHz - 3 MHz
* T50-1 .500 .303 .190 10 280 Blu/Clr150 KHz - 3 MHz
* T68-1 .690 .370 .190 11.5 280 Blu/Clr150 KHz - 3 MHz
* T130-1 1.30 .780 .437 20.0 280 Blu/Clr150 KHz - 3 MHz
* T25-2 .250 .120 .096 3.4 95 Red/Clr250KHz - 10 MHz
* T30-2 .307 .151 .128 4.3 95 Red/Clr250KHz - 10 MHz
* T37-2 .375 .205 .128 4.0 95 Red/Clr250KHz-10MHz
* T44-2 .440 .229 .159 5.2 95 Red/Clr250 KHz - 10 MHz
* T50-2 .500 .303 .190 4.9 95 Red/Clr250 KHz - 10 MHz
* T68-2 .690 .370 .190 5.7 95 Red/Clr250 KHz - 10 MHz
* T80-2 .795 .495 .250 5.5 95 Red/Clr250 KHz - 10 MHz
* T94-2 .942 .560 .312 8.4 95 Red/Clr250 KHz - 10 MHz
* T106-2 1.06 .570 .437 13.5 95 Red/Clr250 KHz - 10 MHz
* T130-2 1.30 .780 .437 11.0 95 Red/Clr250 KHz - 10 MHz
* T157-2 1.57 .950 .570 14.0 95 Red/Clr250 KHz - 10 MHz
* T200-2 2.00 1.25 .550 12.0 95 Red/Clr250 KHz - 10 MHz
* T225-2B 2.25 1.40 1.00 21.5 95 Red/Clr250 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 TempCoColor Wideband Xfmr Power Xfmr RFI suppresion
* FT240-31 2.40 1.40 .500 3180 16000Black 1 MHz - 300 MHz .5 MHz - 30 MHz 1 MHz - 500 MHz
* FT23-43 .230 .120 .060 158 12500shny Blk 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT37-43 .375 .187 .125 350 12500shny Black 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT50-43 .500 .281 .188 440 12500shiny Black 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT82-43 .825 .520 .250 470 12500shiny Black 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT114-43 1.14 .748 .295 510 12500shiny Black 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT140-43 1.40 .900 .500 885 12500shiny Black 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT240-43 2.40 1.40 .500 1075 12500shiny Black 5 MHz - 400 MHz .5 MHz - 30 MHz 5 MHz - 500 MHz
* FT290-43 2.90 1.53 .500 1275 12500shiny 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 TempCoColor 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

Resistor Values for 50 Ohm Attenuators

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 Enclosure Dimensions

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

driving a nail under construction...

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