Many things....? Layout being the most important.
Copying the board layout with leaded parts on copper (dead bug) is not the same
and leads will get you.? Also in that format you build power stages in a straight line
with no folding to make the input and output close.
The other can be that your balanced modulator is not!? You will leak carrier as a result.
Again lead length will be a problem, short is a must.
Any band switching such as the output filters need to be far from the input end of the amp.
also the leads to the relays short an may even require shielded wire COAX.
How about a picture?
Allison
