RadioBanter - SWR not set.. WIll it hurt my radio?

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- - SWR not set.. WIll it hurt my radio? (https://www.radiobanter.com/cb/75504-swr-not-set-will-hurt-my-radio.html)

Can you give me a few sites to good internet

dealers since there arent any physical shops

left in my area anymore?

There are plenty of shops in eastern Pa. Where do you want to travel to
find a shop?

From: (Professor)
LOL... no problem... Frank is a little edgy... as usual. You should pick
up something like this http://batterysupply.com/cbantacc1.htm This is
what we've been talking about... a so called "matchbox"...
Professor
www.telstar-electronics.com
_
How 'bout them changes to your amp, Mr. Griff? Were they truly
rec.radio.cb inspired?

From: (John=A0Smith)
professor:
Funny, that pic won't show in my browser...
John
_
"Professor" wrote in message
oups.com...
LOL... no problem... Frank is a little edgy... as usual. You should pick
up something like this http://batterysupply.com/cbantacc1.htm This is
what we've been talking about... a so called "matchbox"...
Professor
www.telstar-electronics.com
_
Perhaps you got great spam control not unlike myself. Anyhoo, his link
takes you to a CB dealer's website in Paris, Illinois.

"Frank Gilliland" wrote in message
...
On Mon, 01 Aug 2005 22:49:22 GMT, "U-Know-Who"
wrote in :

"Frank Gilliland" wrote in message
. ..
On Sun, 31 Jul 2005 08:36:55 -0700, "John Smith"
wrote in
:

tnom:

Yep, I always worry about terminology...
It will allow you to tune the antenna/coax from a 5:1 to a 1:1 and run
your
transceiver into it--WITHOUT BURNING OUT THE FINALS.

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.

Frank, to be fair, you must now finish this statement. Even at 3 watts,
some
of these tiny radios and chassis don't have enough mass to dissipate the
heat that will be created by the miss-match. Sure, you can add a larger
sink
and forced air cooling, but stock, they won't take it.

I have yet to see a CB radio that couldn't handle a 3:1 SWR (unless it
was improperly installed, as you mention below). And I know that those
plastic Cobra 19's and those micro-Midlands can be keyed at a normal
duty cycle without -anything- hooked up to the antenna jack. Some of
the older radios are a bit fussy, especially those with the 2SC799.
But those are becoming quite rare -- probably for just that reason.
The 2SC2078 and other modern CB finals are solid transistors that are
pretty darn hard to blow, with or -without- a heatsink (the TO-220
case dissipates quite a bit of heat all by itself).

And it's never a bad
idea to check the heat sink and mica insulator and replace the grease with
Arctic Silver 5 or some comparable superior thermal compound. I lost an
MRF477 due to improper installation by the manufacturer. The screw had
been
stripped and was not making proper contact with the heat sink, and that
was
with a reasonable SWR.

I have seen a few Unidens with those thick, grey, rubber heat-sink
insulators -- worthless crap like that shouldn't have even been
installed at the factory. Another problem I've seen is amp junkies
(audio and radio) who replace their own transistors and use -WAY- too
much heat sink grease. They were never taught that it's only meant to
fill the air gaps where there's no direct contact -- IOW, just a
little dab'll do ya.

Ain't that the truth! It's not magic, and like you said, it's only to fill
the microscopic gaps. And to be honest, you can do a lot more by lapping the
surfaces to make sure both surfaces are as flat as possible. This applies to
all types of heat sink mating surfaces.

From: (Frank=A0Gilliland)
On Sun, 31 Jul 2005 18:54:41 -0500, driver42 wrote in
:
Geez fellas... I didnt mean to start a war here.

I'm just a turkey driver that wants to do things

as right as I can given my situation with pretty

much having a different turkey everyday. After
reading through this entire thread I think I'm

even more confused :-)
_
Frank Gilliland wrote:
First rule: Avoid any gimmicks or modifications
that claim to give you some profound increase
in performance. It doesn't work that way. The

laws of physics dictate that there are only two

ways to significantly improve your

performance: use a bigger antenna and/or use
more power. Leave the gadgets and gizmos

for the neurotics that want to squeeze every

last milliwatt from their radios (and the morons
who like to watch meter needles bounce).

You like power mics on CB, Frank?

Second rule: Practically all CB radios are the

same

That's why I like an imported export for the mobile. Of course, the
right Icom might work ok, too.

in that they have an output impedance

of

50 ohms. This means that the antennas which
are installed on these trucks are most likely

-already- adjusted for best SWR to a 50-ohm

radio, and will therefore work just fine with

-any- CB radio you choose to buy, matchbox

or not.

Third rule: Don't pray to the SWR god. A

dummy load will give you an SWR of 1:1 but it

doesn't make a very good antenna. Your

antenna is best tuned with a field strength

meter, and many times the best field strength

does -not- coincide with best SWR. If the radio
you choose has an SWR meter included,

great. Think of it as a go/no-go meter: below

3:1 and everything is fine; above 3:1 and you

need to check for a major malfunction like a

disconnected cable, corroded connectors,

busted antenna, etc.

Truckin' wrote:
so here's what I'm gonna do. I

will call a few of these cb shops that I've seen

on the web and ask them for their advise and

explain to them my circumstances of wanting

a good high quality radio "no amp or stupid

toys that make noise" and telling them that I'll

be in a different truck and wont be able to set

the SWR and ask them what would be a good

setup for me. One last question for you all that
have been helpful. Can you give me a few

sites to good internet dealers since there arent
any physical shops left in my area anymore?

Thanks again for your help guys.

Frank Gilliand wrote:
Forget the internet CB shops --

And here I was gonna send him to a TA or similar truck stop near Philla
Philadelphia.

let your fingers

do the walking and contact one of your local

commercial radio communication shops. They

do this stuff professionally, they will verify

everything I have said, and will give you the

-straight- scoop instead of a bunch of CB

hocus-pocus designed to sell crap to naive

CBers like Brian does.

Too bad you don't like the extreme heat. One or another of the many
stations here are always hiring, but then again, the doors are revolving
types mostly at Clear Channel or the other scumbags and they own it all.
We have one community radio station that has lasted over the years on
donations and fundraisers. Tough to hold out when you're independent.