| External Tone Encoder | |||
| Product Code 33 | |||
| Unit | Voltage or Control | No 1 Range of Freq | Product |
| B | 1 | 1 | M |
| Pulse Tone Encoder | +12 VDC (Mobile) | 1 Tone 1050-2400 Hz | Mastr II Mobile |
| E | 2 | 2 | X |
| Digital Tone Encoder | +12 VDC (Station) | 5 Tone 1050-1650 Hz | All Other |
| 3 | 3 | ||
| Internal Battery (Mobile) | 5 Tone 1800-2400 Hz | ||
| 4 | 4 | ||
| Internal Battery (Station) | Digital Tone 590 Hz | ||
| 5 | 5 | ||
| 117 VAC Station | Digital Tone 1500 Hz | ||
| 6 | 6 | ||
| +6 VDC Mobile | Digital Tone 2805 Hz | ||
| 7 | 7 | ||
| Control Center | 10 Tone 1050-2400 Hz | ||
| 8 | |||
| +12 VDC Mobile Automatic | |||
| 9 | |||
| TCC | |||