| Year | 1920 |
| Date | 16-Sep |
| Volume | 43 |
| Issue | 1,012 |
| Page | 232 |
| Category | Electronic |
| Part | 8 |
| Title | Wireless Notes |
| Author | A.V.Ballhatchet |
| Notes | Vacuum Valves and Valve Circuits. A Marconi "round" valve, "Q" valve, a B.T.H. "Audion" valve, a "French" or "R" valve, functioning of various arrangements, typical valve curve, complete circuit showing reaction coil |