The problem with the RCA preamp could be that it is hooked up wrong, or it could be a bad preamp, or both. This is the hookup for the DB8e and the RCA preamp; it should work better than without the preamp.
DB8e > preamp > long coax > grounding block > power inserter > TV
If the signals are too weak for splitting:
DB8e > preamp > long coax > grounding block > power inserter > 3414 > TVs
To combine the CM for VHF only and the DB8e for UHF with no amplification for the CM:
Code:
CM
\ VHF
UVSJ > coax > grounding > power > splitter or 3414 > TVs
/ UHF block inserter
DB8e > RCA
switch set to combined or separate, but preferably combined
The Radio Shack 15-2586 or the AD UVSJ will pass power to the RCA
To combine the CM for VHF only and the DB8e for UHF with amplification for the CM and the DB8e, using the RCA preamp as a combiner:
Code:
CM
\ VHF
RCA amp > coax > grounding > power > splitter or 3414 > TVs
/ UHF block inserter
DB8e
RCA switch separate
If the combined/separate switch in the RCA preamp goes bad in the separate position, use the UVSJ as a combiner:
Code:
CM
\ VHF
UVSJ > RCA > coax > grounding > power > splitter or 3414 > TVs
/ UHF block inserter
DB8e
RCA switch set to combined