[Amps] Vacuum relay isolation

[Bob Maser]

I just completed my Pi-L in my new 3CX3000 amp.  I used a RB3 (DPDT) for
each band with one of the poles of the relay switching the L1 and the other
pole switching L2.  A good friend of mine says that there is only 40db of
isolation between the 2 poles of the relays so I might see some interaction.
Is this true?

Bob  W6TR