Design a network that has a notch at 153 AND passes 146. Just the
notch is not good; it will have significant attenuation at 146. In
terms of poles and zeros, you want a transmission zero at 153 and a
transmission pole at 146.

One way to do this is with a coaxial resonator. The separation is
great enough that it shouldn't take a super-high-Q one. You tap your
input and output a short distance up from the shorted end of a
quarter-wave stub that's open on the other end. The distance from the
open to the attachment point is 1/4 wave at 153MHz, which reflects back
a short to the line at 153. But that's capacitive at 146, and
resonates with the short stub between the attachment point and the
shorted end to yield a high impedance across the line there.. You can
do the same thing with a couple coils and a trimmer cap: something
like 10nH across the line and a series-tuned tank of 100nH and about
10.8pF right at the same place would do it. Coil Q should be pretty
high to have a deep null and avoid loss at 146. You get to figure out
which will give you better performance.

Cheers,
Tom