Entirely reasonable, provided they tell you what the reference is.
A claim of "5 dB gain" is meaningless. In ham circles, when I see this,
I
automatically assume they mean dBi, but given the level of snake oil in
CB
circles, I think in terms of dBdummyload.

....or dB over the transmission line.

dBradiax?




The problem there is that the feedline may be radiating when there is a
mismatch
at the antenna. Regardless, he never indicated the length of the coax -or-
if
the coax was tested for RF on the shield.

This is why I pay $2000/Day to my FCC testing guys. It's not as simple as
it looks!


You may be getting reflection from the other antenna. Try tuning without
the other stick.

That's my primary radio. I use the CB for road conditions, but if one of
them has to compromise..


Didn't someone come out with some sort of quack antenna for cell phones? I
thought I saw that on a TV commercial or something....

Yeah, the "patch" to get your yangtenna up.
I got one free in a parts order once. It's worth at least twice what I paid
for it.
I did give it a fair trial. No noticable effect one way or the other.



Sounds like these "tuning rings" on some current antennas.

The tuning ring on an Astron 99 or similar at least does something.
I use one of those as my HF vertical.

The zing ring was the "cell phone antenna sticker" of it's day.


The thought of 15 KW on a vehicle makes me shudder

Figuring a generous 60% efficiency at the amp, that's 1800A from your
battery, more or less.

You know, I've always known that power dosen't count for much on these
bands, and as I was driving back from Georgia again this weekend, I remarked
to the wife that listening to the truckers fade in and out going the other
direction, I can't tell much difference between the guy that claims he's
running the 150W or 500W amplifier, and the ones that claim not to be..

I certainly don't hear them 20-50 miles away..

-- knowing that the vehicle
itself is carrying the same voltage and current as the antenna, but
terminated
with a gas tank!!!!

Back an August, I was sitting at a gas station fueling up the Expedition,
which does take a while..
I was sitting there, with my 50W aprs transmitter running periodically (on
the glassmount antenna right above the gas tank), the other two VHF
transcievers were shut down. I was making a call on my cell phone, when I
noticed that the truck parked in the next bay was idling, and dripping
something that was spattering on the concrete... The truck was labeled
"liquid oxygen", and "no smoking within 50 feet".. As the cold liquid
oxygen vapor mixed with the gasoline vapor hugging the ground, I was
thinking "and they are worried about my cell phone?"