On Mon, 1 Aug 2005 19:55:10 -0700, "John Smith"
wrote:

Frank:

You might be a nice guy, I see idiots who are nice guys, ma'roons too...

John


Do you see dead people also?

On Sat, 30 Jul 2005 23:11:03 -0700, "John Smith"
wrote:

+The match box is fine, guarantees he will not generate a bunch of shop costs...
+
+Any sensible person knows it is a no brainer...
+
+He doesn't want to get a damn engineering degree, he wants to use it...
+John
******

A matchbox only fools the transmitter into thinking it sees a proper
load. It does nothing for the standing waves that already exist on the
coax. It does not improve antenna performance.

james

On Sun, 31 Jul 2005 12:58:26 -0700, Frank Gilliland
wrote:

+Guess what, John: Most of the finals used in CB radios today (and for
+the past 20+ years) can withstand SWR of 30:1 indefinitely. And that
+includes the power transistors used in amps, too.
*****

At the device's rated power, voltage and current. Exceeding that rated
power, or voltage or current of the device will not guarentee that
device will withstand all SWR up to 30:1 indefinitely.

james

Thank god for Frank, he is right, he is only one to tell truth.


On Mon, 1 Aug 2005 19:55:10 -0700, "John Smith"
wrote in
:

Frank:

You might be a nice guy, I see idiots who are nice guys, ma'roons too...


I'll try this one more time. You will need to focus -REALLY- hard
because this is probably going to be explained on a temporal level
with which you are unfamiliar: logic. Are you ready? Ok, here we
go.....


Fact: Somebody already installed the antennas and coax in the trucks.

Fact: Most people who install antenna systems adjust them for the best
impedance match to their radios.

Now just in case you are worried about the word "most", here are a
couple things to consider: If the antennas and coax are -not- adjusted
for a very good match then the other drivers of these trucks would
have blown -their- finals already (according to your "truth") and
would have either complained or fixed the problem. And since a company
owns the trucks, the antennas and the coax, and apparently wants the
drivers to use CB radios while driving, it's very likely that the
company checked the antenna systems so as to make sure they actually
work and not blow up the drivers' radios. This seems plausible because
if company equipment is defective they could be liable for the cost to
repair or replace the driver's CB radio. Even in a worst-case scenario
where the antenna systems were defective and blew up CB radios all the
time, not only is there something fundamentally wrong with the antenna
systems that no matchbox is going to fix, but someone is bound to warn
him that he should -not- plug his radio into the truck's antenna. So
in all probability.....

Conclusion: The antenna systems on these trucks have been adjusted for
the best impedance match to a CB radio.


Now hold on tight because this is where it all comes together.....


Fact: All CB radios are designed for a load impedance of 50 ohms. From
this fact you can draw two conclusions:

Conclusion #1: A CB radio with a load impedance of 50 ohms was used to
adjust the antenna systems in the trucks for the best impedance match.

Conclusion #2: Any CB radio the original poster uses is going to have
a load impedance of 50 ohms.

And those two conclusions lead to one FINAL conclusion: The antennas
and coax are -already- adjusted for the best impedance match to -any-
CB radio the original poster might use.


Bottom line: He's not going to blow up his radio if he doesn't use a
matchbox.


Now feel free to go back to your troll routine of calling me a "fool",
an "idiot", a "ma'roon" and a "brain-dead whacko", because you just
earned your place in the killfile.


=-PLONK!-=






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On 30 Jul 2005 09:52:56 -0700, "Professor"
wrote:

+It depends on how bad the match is. There is a good chance that you'll
+be OK. It takes a match of perhaps 5:1 or worse to overheat the
+transmit output transistor in most CBs.
+
+Professor
+www.telstar-electronics.com
+
+driver42 wrote:
+ 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?


SWR alone will not destroy a bipolar transistor unless it is operated
outside the Safe Operating Area. The weakest part of a bipolar
transistor is the base emitter junction. Abuse that juntion and the
transistor will not forgive you.

I would venture to say that nearly all CBs on the market if operated
at the legal power levels and within voltage and currnet levels will
handle SWRs well beyond 10:1. At those SWR levels, one will definitely
know that something is wrong with a remarked lost of receive signals.

james

As usual Frank tells the strait truth and everyone scrambles to backpedal on there BS.

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

+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?
*******

Up to about 3:1 the loss in range is minimally discernable. After 3:1
you will notice some loss of receive in weak signals and some gradual
worseing of transmitt range as SWR get higher. This is due to less and
less power delivered to the antenna for radiation.

As for hurting the radio, if you haven't overly modified the original
design or operating the radio outside the specifications that it was
designed for, No. Disconnect the coax from the radio will do more
damage than a poor SWR.

james

On Mon, 01 Aug 2005 18:59:48 -0700, Frank Gilliland
wrote:

+Yeah, at HP I got a peek at a full-blown cost-benefit analysis showing
+increased profits by increasing the employee turnover rate. And to
+think there are some people who think labor unions are obsolete.....
*****

Yep with protable pensionplans they don't have to contribute a much to
them and that is a big savings there.

I think the ghost of Adrew Carnegie is walking the halls of many
businesses to day. Whispering into CEOs ears saying contrtol costs and
profits will increase.

james

On 2 Aug 2005 05:44:15 -0700, "Professor"
wrote:

+Frank... the point you're missing is that although it's like you say
+"All CB radios are designed for a load impedance of 50 ohms."... there
+are certainly different reactances (j factor) from radio to radio. No
+radio or antenna is exactly 50 +j0. This is where the matchbox can help
+to supply the conjugate needed for maximum performance.
+
+Professor
+www.telstar-electronics.com
******

If we take the equation 50 + j0 ohms to be a 50 Ohm impedance then an
equation in this form, x + jy, will yield an infinite solution of
equatins where the magnitude of the impedance is 50 ohms.

Conversely 50 + j50 Ohms is not 50 Ohms impedance.

What does vary from radio to radio is the tuning of the output filter
and matching network. Still this variation is not much greater than
about 5%. That 5% variation will not alter the match between the radio
and the coax significantly.

Finally, SWR is not determined by the mismatch of the radio to the
coax. SWR is determined by the mismatch of impedance of the antenna to
that of the coax. SO variations of source mismatch play a relatively
small degradation in the system performance.

james

On 2 Aug 2005 05:44:15 -0700, "Professor"
wrote in .com:

Frank... the point you're missing is that although it's like you say
"All CB radios are designed for a load impedance of 50 ohms."... there
are certainly different reactances (j factor) from radio to radio. No
radio or antenna is exactly 50 +j0. This is where the matchbox can help
to supply the conjugate needed for maximum performance.


Since CB radios are calibrated at the factory to a 50 ohm nonreactive
dummy load, I find it highly unlikely that a CB radio is going to have
any significant reactance or variation from the designated impedance.

Now look up the word "conjugate" before you misuse it again.







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