If using the XVTR port as the low drive output, there is no output filtering on that port. So to keep spurious emissions within spec, you should use a bandpass filter designed for the center frequency of the TX output to ensure the exciter is provided spectrally clean RF to the amp.
630-meter non-linear amplifier
NOTE: I can no longer produce these amplifiers for sale due to the “15 dB rule” under Part-97 now that the Report and Order has been issued for 630-meters. Parts are available from Mouser and my notes are included below. If you are not a builder, don’t worry as someone will take advantage of the opportunity to design an amp that meets the 15 dB requirement in the very near future.
We'll need a lot more than 15db of help for the transverter output to get a decent signal.
73 de Mike W9OJ