[Mobile-Portable] Question about HF mobile

[Brian K. Gaskamp]

Hello all, I'm new to the list here and also new to HF mobile and I'm having 
a problem that has me stumped.

I'm running a Icom 706MKII with a Hustler 40m ant on my truck.

I can be in front of my house and I get full output on 40m and everything 
works great...

I check into a 40m traffic net during my lunch break and my power out is abt 
50 watts, and swr is 2.3-1...

I just stumped and what could be happening and need some advice, 
suggestions, on what I'm doing wrong...

Or better yet, what happens to my HF mobile from the time I leave my house 
and why it acts like it does once I get to work.

73,
Brian