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.


The fact that, that is better than replacing finals on a daily basis may not
appeal to some--they can chose to NOT use one and burn out their finals, daily,
if they chose...


Resorting to scare tactics? Gee, I don't use a matchbox and the final
in my rig is just fine. In fact, I've -never- blown a final except for
once when the coax connector on the radio end was shorted, but I don't
think a matchbox would have fixed that problem..... do you?


Better yet, he can drop into the radio shop on board a truck stop, explain he
does not have time, or the permission of the truck owners to start revamping
their antennas and coax--


Why stop there? Tell him the -truth-, John: If he doesn't run a
matchbox he'll have to hire an engineer at $200/hr to locate the
optimum location on the truck for the antenna, reinstall the whole
system, tune it up with his $20k HP comm analyzer, etc.....

Judas Priest, it's just a CB radio! Just plug it in and talk!


I am sure the tech will see it as a no-brainer--RUN A
MATCH BOX!


Once again there's that phrase most favored by those who can't make a
logical argument: "It's a no-brainer". Well, since the CB was first
established over 45 years ago the overwhelming majority of CBers have
run their rigs -WITHOUT- a matchbox and they worked just fine. Sorry,
it's not a "no-brainer", but it's about as close as you can get. And
if -you- can't figure it out then apparently a "no-brainer" is beyond
your level of comprehension.







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Frank:

With so many guys like you around, it may seem confusing...

All he needs do is check with a tech...

End of story...

John

"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.


The fact that, that is better than replacing finals on a daily basis may not
appeal to some--they can chose to NOT use one and burn out their finals,
daily,
if they chose...


Resorting to scare tactics? Gee, I don't use a matchbox and the final
in my rig is just fine. In fact, I've -never- blown a final except for
once when the coax connector on the radio end was shorted, but I don't
think a matchbox would have fixed that problem..... do you?


Better yet, he can drop into the radio shop on board a truck stop, explain he
does not have time, or the permission of the truck owners to start revamping
their antennas and coax--


Why stop there? Tell him the -truth-, John: If he doesn't run a
matchbox he'll have to hire an engineer at $200/hr to locate the
optimum location on the truck for the antenna, reinstall the whole
system, tune it up with his $20k HP comm analyzer, etc.....

Judas Priest, it's just a CB radio! Just plug it in and talk!


I am sure the tech will see it as a no-brainer--RUN A
MATCH BOX!


Once again there's that phrase most favored by those who can't make a
logical argument: "It's a no-brainer". Well, since the CB was first
established over 45 years ago the overwhelming majority of CBers have
run their rigs -WITHOUT- a matchbox and they worked just fine. Sorry,
it's not a "no-brainer", but it's about as close as you can get. And
if -you- can't figure it out then apparently a "no-brainer" is beyond
your level of comprehension.







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On Sun, 31 Jul 2005 13:52:44 -0700, "John Smith"
wrote in
:

Frank:

With so many guys like you around, it may seem confusing...

All he needs do is check with a tech...


He did, and as a tech I gave him my advice. I also gave him my advice
as an EE. The advice is the same -- don't waste your time and money on
gimmicks, just plug it in and start talking.


End of story...


I doubt it.







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Frank:

If you were EVER a poor tech, you were a bad one, I know you are a damn liar!

When he asked a real tech they are going to tell him he would be an idiot to
key down on mere 5:1 and hope to not damage his radio in relative short order.

When he asks a tech, he will also know for certain NEVER to bother with your
advice again...

How many other peoples radios have you burnt up with your poor advice, I just
wonder...

John

"Frank Gilliland" wrote in message
...
On Sun, 31 Jul 2005 13:52:44 -0700, "John Smith"
wrote in
:

Frank:

With so many guys like you around, it may seem confusing...

All he needs do is check with a tech...


He did, and as a tech I gave him my advice. I also gave him my advice
as an EE. The advice is the same -- don't waste your time and money on
gimmicks, just plug it in and start talking.


End of story...


I doubt it.







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Newsgroups
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On Sun, 31 Jul 2005 14:11:23 -0700, "John Smith"
wrote in
:

Frank:

If you were EVER a poor tech, you were a bad one, I know you are a damn liar!


Oh gee, another sooth-sayer. What else does your crystal ball tell
you?


When he asked a real tech they are going to tell him he would be an idiot to
key down on mere 5:1 and hope to not damage his radio in relative short order.


I didn't see any part of his posts where he said his SWR was 5:1. Is
that something you divined from your crystal ball?


When he asks a tech, he will also know for certain NEVER to bother with your
advice again...

How many other peoples radios have you burnt up with your poor advice, I just
wonder...


I have absolutely no doubt that you wonder about a lot of things.







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"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. 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.

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. But I will qualify my statement to say that the
RF transistors are rated for continuous 30:1 SWR -only- when they have
a sufficient heatsink.








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"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.

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