| Year | 1930 |
| Date | 16-Jan |
| Volume | 62 |
| Issue | 1,497 |
| Page | 61 |
| Category | Electronic |
| Part | |
| Title | Everyday Wireless Hints |
| Author | "Radiophile" |
| Notes | Balanced armature loud speakers, the output stage, what the power valve does, the anode current, the output of a power valve, about amplification |