My antique radio restoration logs
Ratios were measured by applying a 400hz signal of about 10 volts to the primary and then measuring the primary and half secondary voltages.
| Example Radio | Type | Driver Tube | Output Tube(s) | Output Class | Primary Resistance | Secondary Resistance (ohms) | Ratio (Pri. to 1/2 Sec.) | Notes |
| Truetone D-718 | 6 volt | 30 | 19 | B | 1315 | 472-0-? (1/2 open) | 1.4 to 1 | |
| Philco 624 | 6 volt | 30 | 19 | B | 385 | 149-0-165 | 2.4 to 1 | |
| Airline 62-337 | 6 volt | 30 | 19 | B | 998 | 1222 CT | 2 to 1 | |
| Silvertone 1925 | 32 volt | 76 | 48 PP | A | 892 | 1076-0-1180 | 1 to 1 | |
| Crosley 645 | 32 volt | 85 | 48 PP | A | 1925 | 11.58K CT | 1 to 3 | Very large transformer high inductance. |
| Knight A9725 | 32 volt | 76 | 48 PP | A | 762 | 1524-0-1317 | 1 to 1.46 | |
| Airline 62-377 | 6 volts | 30 | 30 PP | ? | ? | ? | 2 to 1 | Output tube plate=90, bias=6 volts. Class? |
| RCA 6BT6 | 6 volts | 30 | 49 PP | B | ? | ? | 2.34 to 1 | |
| RCA 140 | AC | 56 | 53 | B | 1298 | 62.2-0-69.4 | 5.224 to 1 | 56=76, 53=6N7 |
| Philco 16B | AC | 42(T) | 42(T)PP | AB2 | 400 | 112.5-0-127.8 | 2 to 1 | Driver and outputs Triode connected. Output trans 77(ct):1 connected to voice coil |
| Philco 20B | AC | 27 | 71A | A | 1123 | 2574-0-2913 | 1 to 3.8 ct | Output: 106.8(ct):1 p=231.7-0-205.7 ohms |
| Philco 37-2670 | AC | 6J5 PP | 6F6 PP | AB2 | ? | ? | 2.71 ct to 1 ct | |
| RCA R-7 GE S-22 |
AC | 27 | 45 PP | A | 720 | 5700 (total) | 1 to 2.1 | Output Transformer Ratio 45.6(ct):1 |
| Crosley 124 | AC | 27 | 47 PP | A | 2345 | 4092-0-4170 | 1 to 1.5 | |
| Crosley 146 | AC | 89 | 46 PP | B | 821 | 144-0-156 | 2.95 to 1 | |
| Airline 62-229 | 32 volt | 43 | 6A6 | B | 3.087 to 1 | |||
| Grunow 620 | 6 volt | 30 | 19 | B | 675 | 120-0-133 | ? | |
| Philco 37 | Battery | 30 | 19 | B | 322 | 157-0-170 | ? | |
| Philco 37-38 | Battery | 1H4 | 1J6 | B | 379 | 167-0-151 | ? | |
| Philco 37-38 | Battery | 1H4 | 1J6 | B | 390 | 172-0-151 | ? | |
| Zenith 6J230 | 6 volt | 6L5 | 1J6 | B | 789 | 242-0-216 | ? | |
| Zenith 9S30 | AC | 6C5 | 6F6 PP | AB2 | 1420 | 591-0-663 | 1.5:to 1 | 6F6 Triode Connected, Output Trans 77(ct):1 |
| Zenith 12A58 | AC | 2x 6C5 | 6F6 PP | AB2 | 1414 | 456-0-534 | 1.5 to 1 | 6F6 Triode Connected |
| AK 55C | AC | 27 | 45 PP | A | 1105 | 3480-0-4180 | 1 to 4.39 ct | Output Transformer ratio 76(ct):1 |
| Erla 271-A | AC | 27 | 45 | A | 3550 | 6100 | 1 to 2.982 | Output Transformer ratio 29:1 |