Chris, thanks for the clarification.
Did grounding help with the mini whip?
I already had the miniwhip grounded to the base of the mast. I added another ground point to the top of the mast, which is where it really should have been grounded to start. I was just building it in stages.
Anyway, yeah, grounding an active miniwhip is incredibly important to the antenna performance. Think of the ground as the other "half" of the antenna just like a basic half-wave dipole has two "sides."
If you do not provide a decent RF ground path, then the miniwhip primarily uses your coaxial feedline as its RF ground via common mode. Sometimes that works okay, but for many deployments that introduces increased EMI/RFI in to the situation. A miniwhip relies on a high-gain preamp for its performance, and that is already putting an increased noise profile into the receive path. Also there is the issue of a miniwhip being an e-field antenna, thus being particularly susceptible to local EMI/RFI coupling. You want to limit noise ingress as much as possible. Improving RF grounding and feedline decoupling are good places to start.
The 10.5' masts for my active whips have provided enough RF grounding for my particular deployment and casual listening purposes IMO. However, going to an extreme, look at what the popular Twente WebSDR does. Its active minwhip if RF grounded to a large metal roof of a building at 20 meters height above ground. o.0
http://websdr.ewi.utwente.nl:8901/qrt.htmlhttp://www.pa3fwm.nl/technotes/tn09d.html
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