[mythtv-users] Increasing ATSC signal strength going into DVB card

[MythTV]

Ever since the decommission of NTSC, my ATSC signal strength has been  
about 30% lower than before across all channels.  Unfortunately, the  
channel we watch the most now only has a signal strength of 11% which  
is not enough for MythTV to lock on nor record from.  Before July  
12th, our favorite channel had a signal strength 51%.

I do have a signal amplifier on my antenna cable. It's a Blonder  
Tongue Broadband VHF/FM/UHF Distribution Amplifier.  I've been told  
that it is good enough for my area but I'll change if there's a  
better one to use.  Here's the URL to my amplifier:
http://www.sjmediasystem.com/zta-15.html

I also have a Digital Converter box connected to the same splitter  
where both pcHDTV HD-5500 cards are connected; the converter reports  
a signal strength of 40% on the channel in question where MythTV  
reports only 11%.

I have tried changing the direction of my antenna.  No luck.

Is there a way to increase the signal strength going into the pcHDTV  
HD-5500? Or, is there a way to make the pcHDTV HD-5500 more sensitive  
to the signal it is being fed?

Rob
My configuration is:
MythTV version: 0.21.20080304-1 18722
Ubuntu 8.10, kernel version: 2.6.27-9-generic
CPU: Intel Pentium 4 CPU 3.2GHz Socket 775 800 FSB w/Hyper Threading
Technology
Memory: 1Gig DDR 333 Memory 180 Pin
Motherboard: ASRock 775i65G Mother Board
Optical Drive: LG 18X DVD RW + Dual Layer
Hard Drive: 1 Western Digital 250 Gig HD contains the OS and 1
Western Digital 1 TB 7200 RPM Cache Serial ATA contains the video data
Video onboard: Integrated SiS Ultra256 2D/3D Graphics
Video card: Micro-star International (MSI) AGP GeForce FX5200-
TD128LF, 8X, 128M, DDR1, D-Sub, DVI-D, TV-out
Audio onboard: AUDIO ADI AD1888 6-channel audio CODEC
Audio card: Riviera C-Media CMI 8738 (Connected to my entertainment
center via the optical cable)
Network Card: Onboard 10/100 Network Card
Tuner cards: 2 pcHDTV HD-5500