question about antennas and skip from the pros.

Hiya, Logan.
A couple of things come immediately to mind, but they *may* not apply here. My best guess is that your base installation has an antenna that's much higher in the first place, up a little farther away from some of the sources of man-made noise that your truck has to endure (or that it also generates). And that "old base antenna" could very well be a superior performer in the first place than the Predator that you've got on the truck, or anything else that you've tried on the truck as well. Nearly anything that you can put on a vehicle will, by necessity, be some sort of a compromise because of the limitations of available metal area that we've come to call "ground plane", and anything shorter than about 106"-ish will be a lossy antenna. A typical "base antenna" from years gone by, unless it was designed to fit into a restricted height location, might well be over 18 feet tall, and actually exhibit gain.
So add the benefits of greater height, greater antenna gain, and lower "site noise", and it's not much of a surprise that, given the info you've stated, your base hears stuff that your mobile never does.
But park your truck on a tall hill and shut off all the electrical systems that you can and you might recover many of those losses. It would be an interesting experiment, and give you a chance to try it out for yourself. And keep in mind that the "big radio" in your truck typically only has more "oomph" in the transmitter; the Cobra has a pretty nice receiver, hard to beat.
Others will doubtless have more ideas; those are just the first ones that jump out at me.
Drive safe,
Handlebar

 

Simply put, your antenna is way high in the air, and it "sees" more than a mobile antenna usually does. That allows you to talk farther AND receive farther too.

Even better is if your home happens to be on top of a big hill, mountain, etc that overlooks the surroundings.

Of course we do not know if the feed point of the antenna or the tip is 3 stories high, nor do we know what type of antenna you have. So therefore if you have for instance, a 24' tall Imax 2000 with the feed point at 30 ft. up, that puts the tip of the antenna at 54 feet.

 

Funny, I hear all kinds of skip with my Wilson Trucker 2000 in my truck, all the time. I just can't talk back it seems.

 

Let's see...

Base antenna: ~18' of metal in the air.
Mobile antenna: ~3' of metal in the air.

Base: 30' high - low angle of radiation (favorable for skip)
Mobile: *maybe* 8-9' high (higher angle of radiation)

Base: Either has radials (ground plane), or a design that doesn't need a ground plane
Mobile: Has little to no ground plane

Simply put, the base antenna puts out (and hears) a LOT better than the mobile antenna.

Also, there is nothing magical about 9' (or multiples thereof) lengths of coax. With the velocity factor figured in, 9' is just under 3/8 of a wavelength at 27 MHz.

 

This all reminds me of back in the day when a friend and I would go out on a high hill with a radio,a 100 watt linear, an ice chest full of cold refreshments, and a Cushcraft Ringo antenna on a push up pole. We'd set it up using the spare tire to help anchor the push up poll, and enjoy hours of talking "long distance". This was always done at night so there wasn't a lot of skip talking going on, but we'd talk 50 miles or better to surrounding towns and communities. Awwww the good ol' days!!!!

 

Sounds like a single op Field Day contest station in June, but without the competitive pressure and the annoying logs

 

Glad you made it back down the hill in one piece. You got some pretty nastiy hills and curves in your neck of the woods.

 

Those were the good ol days. Talking to a base in Springfield, MO was quite a feat back then. Get over towards West Plains sometimes too. I was up on a mountain top the other day and talked a good 50 to 60 miles with my little Pro510 and Wilson 1000. Hit them with about 9 pounds!!