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I gather the CA7078 has been in place for several years at this point? A small amount of corrosion, particularly at the connection between the antenna phasing lines and the matching transformer could produce low signal output, skewed pattern & intermittent symptoms affected by changes in temperature or humidity.
@Electron mentioned the Winegard HD7698P earlier, and in your situation it makes sense to consider using one. I honestly believe you should be able to gather enough signal out of the air... with no amplifier at all.
Before you do that though, a less expensive upgrade can be tried. Add an FM trap. You can find them at Radio Shack, Cat. No. 15-024. You may find it helps with real CH 7 and possibly others. It needs to install between the antenna and the preamp. (The second harmonic of KCRW-FM, 89.9MHz lands in the top end of real CH-7's bandwidth. {89.9 * 2 = 179.8}... Real CH-7 is 174 to 180 MHz.) If you replace the antenna, the addition of the FM trap is still prudent.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
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Last edited by GroundUrMast; 27-Jun-2012 at 7:39 AM.
Reason: Commentary re. KCRW-FM
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