Which of the following is required in the identification transmissions from a balloon-borne telemetry station?
Call sign✓Bonne réponse
The output power of the balloon transmitter
The station's six-character Maidenhead grid locator
All these choices are correct
Explication
A balloon-borne telemetry station below 50 kilometers is an ordinary amateur station, so the general identification rule applies and the assigned call sign must be transmitted. Transmitter power and grid locator are not identification requirements anywhere in the rules.