On Mon, 1 Aug 2005 14:46:55 -0700, "John Smith"
wrote in
:

Frank:

FOOL!!!

His original post makes ALL of that clear, if not, one or two of his other
posts after will fill you in...


Well, let's find out just what he said, shall we?


=====
On Sat, 30 Jul 2005 11:45:50 -0500, driver42 wrote
in :

Hi,
If I'm not able to set the SWR in the trucks that I drive will it hurt the
radio or just give me decreased range?
=====


I don't see anything about a 5:1 SWR.

I don't see anything about being "forced" to use a matching device.

Now is a good time to dispell more CB mythology: Many of you already
know that in order to double your range you need -four- times the
power. But it also works the other way -- if you reduce your power to
one fourth (i.e, you are losing 3/4 of your power, which would mean a
pretty high SWR) you have -only- decreased your range by one half. So
an SWR of 2:1 or 3:1 (or, conversely, squeezing a couple extra watts
with a tweak-n-peak) isn't going to have a noticable effect on your
range.

Let's continue with the scenario that you are losing 3 watts (3/4 of
your power) due purely to reflection. Ok, so that power gets dumped
back into the final where it's dissipated as heat. That's three extra
watts in a transistor conservatively rated to handle a certain amount
of -continuous- heat dissipation, which is usually something along the
lines of 4 watts. Mind you that 3 or 4 watts isn't a whole lot of
power; if the heat sink can handle 4 watts without a problem then an
extra 3 watts isn't exactly going to melt the knobs. Regardless, the
final -isn't- dissipating this heat continuously (unless the OP is one
of those asshole broadcast types that keys down for half an hour), so
normal operation certainly isn't going to "cook" the transistor. And I
already mentioned that these transistors are rated to handle 30:1 SWR
-continuously- without damage.

If you want proof of these FACTS then feel free to refer to the data
sheets for the final transistors most commonly used in CB finals.


=====
On Sat, 30 Jul 2005 13:27:48 -0500, driver42 wrote
in :

My problem is that I'll be moving from truck to truck so I wont have
time to set the SWR correctly. Most of our trucks have factory installed
double antenna's which I'm not too thrilled about.
=====


I don't see anything about a 5:1 SWR.

I don't see anything about being "forced" to use a matching device.

Looks to me like he said the trucks already have antennas installed.
Assuming they are CB antennas, it's more than likely that the antennas
have already been trimmed for use with a 50-ohm radio (since all CB
radios are 50-ohm radios). Unless something is broke, the antennas are
probably going to give a reasonably good match to -whatever- radio he
picks (because, once again, all CB radios are 50-ohm radios).


=====
On Sat, 30 Jul 2005 21:33:43 -0500, driver42 wrote
in :

My problem is that I'll be in a different truck everyday and
wont be able to set the SWR the way I want to.
=====


I don't see anything about a 5:1 SWR.

I don't see anything about being "forced" to use a matching device.

What I -do- see is concern about setting the SWR, which is another
mythconception (and not just with CBers but with a lot of hams). A 1:1
SWR does -NOT- mean the antenna is operating at it's best efficiency.
It -DOES- mean that the load is 50 ohms nonreactive. But a 50 ohm
nonreactive load can be darn near anything: a carbon resistor, a dummy
load, a bad coax working as a tuned stub, or even a corroded 9' whip
with a mount caked in mud (seen both scenarios firsthand).

As I stated before, an SWR meter is a go/no-go meter. If it normally
reads 2:1 then suddenly jumps to 6:1, that's a good indication that
something has gone wrong with the antenna or coax. And -THAT'S- what
an SWR meter is good for..... a "something's wrong" meter (IMO, they
should probably be replaced with idiot lights like those in a car.)

If you want to tune your antenna for best efficiency you -NEED- to use
a field strenght meter. Period.


Now........ once again........

1) Where did the original poster say he was being "forced" to use any
type of matching device?

2) Where did the original poster say his SWR was 5:1?

3) Since very few CBers use a matchbox, why don't the millions of
other CB radios have blown finals?









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