I've got a fairly late phase vasari game going on... I'll take a peek later tonight when I get home and try to confirm this. Were you noticing this on only one jammer, or did it happen on all of them? Did the jammer have the upgrade tech or not?

-Itharus

EDIT: No, it's not how it's meant to work. It's supposed to activate when enemy vessels are in it's range (the range is pretty substantial though).

That happens to the antimatter recharger for the Advent as well.

Also, don't forget that their Phase Missile techs are the most economical weapon upgrades in the game. Bypassing shield mitigation(which is actually applied to all attacks even when the shields are down) is a great boon. Many of their ships also use Phase Missiles, from bombers to Assailants to Sentinels and capital ships. As for capital ships, I like the Desolater myself. Siege capitals tend to have most of their firepower concentrated forward. The Desolater in particular is also very flexible at taking down structures and planets, with its phase missile swarms doing nice damage to groups of enemies. But yeah, overall Vasari caps aren't too great, neither is their super weapon(its best use is to disable defense structures or to slow expansion of culture, perhaps to dent the economy on a trade port laden world so that you will need more payday installment loan in the game). But their regular ships are among the strongest in the game, and their mastery of phase space lets them get around very quickly. Their nano weapon jammer tactical structure makes it very hard to assault entrenched worlds with a defense fleet stationed(and really slows enemy planet bombardment runs).