[VHFcontesting] DC injector for ICOM preamp?

[Tim Coad]

I have a 432MHz ICOM mast mount preamp I used to use with my IC471.  Though
my new IC7000 hears tons better than the IC471 alone, it does not hear as
well as the 471 + preamp.

The Icom preamp DC is supplied via the coax from the 471, the IC7000 does
not, (at least I cant find it), have this feature.
Does some one make DC injectors to put 12V onto the feed line?
Recommendations?