I've not used a 19 set on the air . A radio tech. friend of mine tested a 19 set RF transmit output on a modern spectrum analyzer and the total RF output seen from the 19 set is actually a sum of the frequency you want ( if the PA is set correctly ) , plus various spurious emissions . The meter on the set can lead you astray because it measures the total RF output , it doesn't care what frequency it's measuring, it adds the whole RF output together . I think the PA tuning circuit has a low 'Q' , meaning its a rather broad filter in effect. Because the PA tuner is so coarse , you can easily tune the PA for the wrong side of the mixer output, meaning you will actually be on the wrong frequency .