MFJ-557 oscillator with key
CW practice oscillator with telegraph key, adjustable volume and tone, headphone jack and external speaker, 9 V battery
The MFJ-557 is a CW practice oscillator with key for practising Morse code at home, at work or in the field: it is compact and easy to take anywhere.
Product description
The internal speaker volume adjusts from barely audible to maximum, and the tone control ranges from high to low pitch. There is a headphone jack for private practice and an external speaker can be connected for classroom listening.
The key contacts are adjustable. When you are ready, you can connect the key directly to your transmitter or transceiver and get on the air.
Key features
Adjustable contacts.
Wide adjustment.
Privately or in the classroom.
Compatibility and notes
It runs on a 9 V battery (not included) or an optional power supply.
Technical specifications
| Type | CW practice oscillator with key |
| Adjustments | Volume, tone, key contacts |
| Outputs | Headphone jack, external speaker |
| Power supply | 9 V battery (not included) or optional power supply |
HamRadioShop | CW accessories
