21. In addition, many UHF bands, many radio amateurs pursue awards based on Maidenhead grid locators. 22. Among radio amateurs worldwide the award remains very popular. 23. Radio amateurs use a variety of transmission modes, including Morse code, radioteletype, data, and voice.24. Before using the system it is necessary for a radio amateur 's call sign to be validated. 25. A radio amateur might introduce spark wireless telegraphy. 26. He is also a licensed radio amateur operator. 27. Like her father Bhumibol Adulyadej Princess Ubolratana Rajakanya holds radio amateur with the call sign HS1D 28. Experimenter Publishing created a magazine devoted to radio in July 1919, " Radio Amateur News ". 29. The tower has been home to the VFDB Hamburg section's radio amateur club station " DF0HHT ". 30. Unlike that required to qualify for a radio amateur licence, no proof of technical competence was needed.
