Sorry if this should be in the Technical area.
There is a local repeater that usually everyone says I'm heard very low. Very clear, but, low. It's only that repeater, it seems. Every radio check on other local repeaters say I'm heard loud and clear. I even make sure there is no background noise such as air conditioning. I hold the mic no further than three inches from my mouth and not angled. I haven't tried any of my handhelds, but, the only mobile unit (hooked up as a base), sounds low.