Hi,
It seems well-known that the SWR value that you read on an external meter or
an antenna tuner is NOT the value measured between itself and the antenna.
The SWR value "picked-up" and that you can change is the one measured
between this meter or tuner and the transceiver (or the linear amplifier but
we consider it as a black box if you use it properly).

But recently I experimented the burning of my PL due to a high SWR, thus
high current, and moisture and the end of the line (really, see image of
PL's here http://www.astrosurf.com/lombry/qsl-...sion-line2.htm, end of
page ).

The distance between my RTX and SWR reader is short, about 1 m. But there
are about 15m between the SWR and the feed point of my antenna where I had
the problem.

So I would like to know if an SWR meter does only read the value upstream or
if the properties of the feedline to the antenna does not influence is
reading.
At first sight it does as during this problem I had a SWR 4:1 on the
external SWR-meter. This value didn't come from the RTX side which built-in
SWR displayed a VSWR 1:1. It really came from the other side, to the
antenna, thus contrary to what I think and what is usually stated about the
functioning of this device...

Can someone explain me this ?

Thanks in advance

Thierry
ON4SKY

It seems well-known that the SWR value that you read on an external meter
or
an antenna tuner is NOT the value measured between itself and the antenna.
The SWR value "picked-up" and that you can change is the one measured
between this meter or tuner and the transceiver (or the linear amplifier
but
we consider it as a black box if you use it properly).

But recently I experimented the burning of my PL due to a high SWR, thus
high current, and moisture and the end of the line (really, see image of
PL's here http://www.astrosurf.com/lombry/qsl-...sion-line2.htm, end
of
page ).

The distance between my RTX and SWR reader is short, about 1 m. But there
are about 15m between the SWR and the feed point of my antenna where I had
the problem.

So I would like to know if an SWR meter does only read the value upstream
or
if the properties of the feedline to the antenna does not influence is
reading.

The SWR meter indicates the value from the meter to whatever is after it.
If you insert a device that has a high SWR (because it becomes defective or
for some other reason ) between the transmitter and SWR meter ( say a switch
or filter), the meter can show a low value if the antenna is ok, but the
transmitter will see a high SWR and may burn out the finals.

The SWR meter indicates the value from the meter to whatever is after it.
If you insert a device that has a high SWR (because it becomes defective or
for some other reason ) between the transmitter and SWR meter ( say a switch
or filter), the meter can show a low value if the antenna is ok, but the
transmitter will see a high SWR and may burn out the finals.

He did not say he inserted anything, just that moisture at the end of his
transmission line caused a fault. If this was the case, an SWR bridge at the
output of his Power Amps should have alerted him to a problem that would
potentially destroyed them.
If you want to use an SWR bridge as a protective device, or indicator, it
must be placed in the proper position in the antenna system. Modern
transceivers have circuits that detect mismatches and reduce power to minimize
failed output devices.


73 Gary N4AST

"JGBOYLES" wrote in message
...
The SWR meter indicates the value from the meter to whatever is after it.
If you insert a device that has a high SWR (because it becomes defective
or
for some other reason ) between the transmitter and SWR meter ( say a
switch
or filter), the meter can show a low value if the antenna is ok, but the
transmitter will see a high SWR and may burn out the finals.

He did not say he inserted anything, just that moisture at the end of his
transmission line caused a fault. If this was the case, an SWR bridge at
the
output of his Power Amps should have alerted him to a problem that would
potentially destroyed them.
If you want to use an SWR bridge as a protective device, or indicator,
it
must be placed in the proper position in the antenna system. Modern
transceivers have circuits that detect mismatches and reduce power to
minimize
failed output devices.

Indeed. A good suggestion I could install (in case of)
Thierry



73 Gary N4AST

"JGBOYLES" wrote in message
...
The SWR meter indicates the value from the meter to whatever is after it.
If you insert a device that has a high SWR (because it becomes defective
or
for some other reason ) between the transmitter and SWR meter ( say a
switch
or filter), the meter can show a low value if the antenna is ok, but the
transmitter will see a high SWR and may burn out the finals.

He did not say he inserted anything, just that moisture at the end of his
transmission line caused a fault. If this was the case, an SWR bridge at
the

The install was : RTX +50 cm RG58 + AMP + 1m Aircom (like RG213) + SWR +15m
Aircom + G5RV

the built-in SWR of my RTX TS-570D read SWR 1:1. If my external SWR
displayed an SWR 4 that means that it read the info AFTER it, what looks
in contradiction with what ARRL website states in his technical columns...
Who's right ?

Thierry
ON4SKY
http://www.astrosurf.com/lombry/




output of his Power Amps should have alerted him to a problem that would
potentially destroyed them.
If you want to use an SWR bridge as a protective device, or indicator,
it
must be placed in the proper position in the antenna system. Modern
transceivers have circuits that detect mismatches and reduce power to
minimize
failed output devices.


73 Gary N4AST

Thierry wrote:
the built-in SWR of my RTX TS-570D read SWR 1:1. If my external SWR
displayed an SWR 4 that means that it read the info AFTER it, what looks
in contradiction with what ARRL website states in his technical columns...
Who's right ?

The SWR between the transmitter and the antenna tuner is usually adjusted for
1:1. The antenna tuner doesn't affect the SWR between the antenna tuner and the
antenna. It can be almost any value. Nothing strange at all about a 4:1 SWR
after the antenna tuner.
--
73, Cecil http://www.qsl.net/w5dxp



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The install was : RTX +50 cm RG58 + AMP + 1m Aircom (like RG213) + SWR +15m
Aircom + G5RV. the built-in SWR of my RTX TS-570D read SWR 1:1. If my external
SWR
displayed an SWR 4 that means that it read the info AFTER it, what looks
in contradiction with what ARRL

Thierry, If your external SWR meter is after the amplifier, in a 50 ohm
system, and it read 4 it could possibly destroy your amplifier output devices.
The fact that the built-in SWR meter in the Kenwood read 1:1 only means the
input match to the Amplifier was good. If the 570 has a built-in tuner, it
will try to get a 1:1 match, no matter what is downstream. It doesn't mean the
output the Amp sees is good.
As for the ARRL, I haven't had the time to look, but I hope they are not
stating that a 50 ohm output Amp operating into 4 mismatch is a good thing.

73 Gary N4AST

"JGBOYLES" wrote in message
...
The install was : RTX +50 cm RG58 + AMP + 1m Aircom (like RG213) + SWR
+15m
Aircom + G5RV. the built-in SWR of my RTX TS-570D read SWR 1:1. If my
external
SWR
displayed an SWR 4 that means that it read the info AFTER it, what
looks
in contradiction with what ARRL

Thierry, If your external SWR meter is after the amplifier, in a 50 ohm
system, and it read 4 it could possibly destroy your amplifier output
devices.
The fact that the built-in SWR meter in the Kenwood read 1:1 only means
the
input match to the Amplifier was good. If the 570 has a built-in tuner,
it
will try to get a 1:1 match, no matter what is downstream. It doesn't mean
the
output the Amp sees is good.
As for the ARRL, I haven't had the time to look, but I hope they are not
stating that a 50 ohm output Amp operating into 4 mismatch is a good
thing.

No no, they only tell that a SWR-meter place this way read the SWR "between
itself and the RTX"...
I am not agree with this sentence... as my SWR 4:1 was well read AFTER it,
thus between itself as they state and the antenna rather !

Thierry


73 Gary N4AST

The TS 570D is driving the amplifier which shows an excellent load for
the TS 570D!!

The amplifier is driving a different load with a 4:1 VSWR. This is a 36%
reflection of the power. If your Amplifier is vacuum tube with tuning
controls it is not a serious condition. You can vary the loading
controls for reasonable output without damage. If your amplifier is
solid state then you have to do something to correct the VSWR because it
presents a load to the amplifier that is outside the designed load range.

Deacon Dave, W1MCE

"Dave Shrader" wrote in message
news:ri_Ob.101568$8H.152471@attbi_s03...
The TS 570D is driving the amplifier which shows an excellent load for
the TS 570D!!

The amplifier is driving a different load with a 4:1 VSWR. This is a 36%
reflection of the power. If your Amplifier is vacuum tube with tuning
controls it is not a serious condition. You can vary the loading
controls for reasonable output without damage.

Hi,

Correct. This is well what I did, rotating the amplifier load knob (a
kenwood TL922) to reduce the SWR as I could not reduce it another way
(antenna side) due to my defect balun.

73
Thierry

If your amplifier is
solid state then you have to do something to correct the VSWR because it
presents a load to the amplifier that is outside the designed load range.

Deacon Dave, W1MCE