Concerning operating scanners in a car...
I learned from experience that even if you turn it off, even if you have 
batteries in it, leaving a plug in the adapter jack and then cutting off 
power to it is a bad idea.  The internal batteries are bypassed, leaving 
programmed frequencies to the mercy of "memory backup", which may or may not 
be enough to last a long holiday weekend.
In my case it wasn't.  Re-programming 18 frequencies was no big deal.  The 
thought, however, of re-programming a couple hundred frequencies...
I'm sure my Pro-2042 will retain memory without outside power for much longer 
than my first handheld could.  The manual says the memory backup is on the 
order of months, and if I go that long without cranking my car, it wouldn't 
start anyway.  :-)
However, the manual also says something to the effect that while the memory 
backup will become active only minutes after the scanner is powered up, the 
scanner must be powered for a few days before maximum protection is 
available.   So, it occurs to me that if I'm running the scanner from a power 
source that is active, say, only 40 minutes a day (20 min to/from work), 
while memory backup must be active the other 23 hours and 20 min, it's 
possible that the battery or whatever will "lose ground" and eventually my 
programmed frequencies will go bye-bye.
Also, my CB forgets what channel I left it on if I leave it without power for 
more than a few minutes.  :-)
Anyway, aside from wiring my scanner so that it gets power from the car 
battery regardless of whether the switch is on or not, what are my options? I 
was thinking that maybe a good-sized capacitor might charge in minutes yet 
provide days of 'parasitic' backup power for scanners and CB's.
Comments?
... ROA #3:  Never pay more for an acquisition than you have to.
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