This is an AM transmitter that this guy built. He says it’s rich in harmonics – it has no tuning nor low pass filtering and the stages are class C, no forward bias. It should have all the things used to minimize harmonics, like a low pass filter. Class C operation is used to maximize efficiency. But in this case it’s not efficient. That’s not a good design.
Link was http but should be https, so if the first one doesn’t work, try the second one.
http://qrp.gr/amtx/?fbclid=IwY2xjawE_b8NleHRuA2FlbQIxMQABHXkD_uTjrCNfhMCsmN9tMrjHkM8DZb4pqg55SMOYwChbXBQ7_-JhSax9fA_aem_tEygvAikJ6zJktZqw–o1A
https://qrp.gr/amtx/?fbclid=IwY2xjawE_b8NleHRuA2FlbQIxMQABHXkD_uTjrCNfhMCsmN9tMrjHkM8DZb4pqg55SMOYwChbXBQ7_-JhSax9fA_aem_tEygvAikJ6zJktZqw–o1A