"K9SQG" wrote in message
...
There are several reasons why maximum field strength and minimum SWR don't
occur at the same points, necessarily. The field strength can be
considered
part of the "efficiency" of the overall system. SWR just relates to the
match
between the feedline and the coax. Think of the dummy load example; it
might
exhibit close to a 1:1 SWR but radiates little power.

A dummy load is also physical proof of the existence of an isotropic
radiator (albeit a rather poor radiator g).

Ed
WB6WSN

"nathan" wrote
I have always heard that this is true, and that I should tune antennas
for maximum field strength and not for minimum SWR. Why wouldn't they
occur at the same time?

.................................................. ......

Minimum SWR informs you your transmitter is loaded with the nearest possible
impedance to 50 ohms.

Maximum field strength informs you your transmitter is sending out maximum
possible power.

There's no way of knowing whether or not the two conditions coincide.

It may occur at maximum field strength that the load on the transmitter
causes distortion and poor efficiency in the PA with excessive internal
volts or amps or watts.

So to avoid flogging the PA or power supply to an early death you should
always tune up to minimum, preferably zero SWR.

You have to balance the probabilities. What are the chances of winning the
contest before the PA issues smoke.
----
Reg, G4FGQ

Two different issues Reg, Does a tuner change the SWR of an antenna? Or
does it simply transform an impedence to one that makes the transmitter
happy? Will the maximum field strength coincide with 1:1 SWR at the tuner in
all cases?

With my old DX-100 with Pi net output (read not stuck with a 50 ohm output)
I tuned for the max field strength that did not exceed the current ratings
of the 6146's. I will admit that in a contest the rule changed to "Tune
for maximum smoke and replace all charred components".

Having an SWR bridge is like wearing dark trousers, if you pee your pants,
no one notices - but it gives you a warm feeling. As soon as I become
dictator of the world, I am outlawing them...

"Reg Edwards" wrote in message
...
"nathan" wrote
I have always heard that this is true, and that I should tune antennas
for maximum field strength and not for minimum SWR. Why wouldn't they
occur at the same time?

.................................................. .....

Minimum SWR informs you your transmitter is loaded with the nearest
possible
impedance to 50 ohms.

Maximum field strength informs you your transmitter is sending out maximum
possible power.

There's no way of knowing whether or not the two conditions coincide.

It may occur at maximum field strength that the load on the transmitter
causes distortion and poor efficiency in the PA with excessive internal
volts or amps or watts.

So to avoid flogging the PA or power supply to an early death you should
always tune up to minimum, preferably zero SWR.

You have to balance the probabilities. What are the chances of winning
the
contest before the PA issues smoke.
----
Reg, G4FGQ

Two different issues Reg, Does a tuner change the SWR of an antenna? Or
does it simply transform an impedence to one that makes the transmitter
happy? Will the maximum field strength coincide with 1:1 SWR at the tuner in
all cases?

With my old DX-100 with Pi net output (read not stuck with a 50 ohm output)
I tuned for the max field strength that did not exceed the current ratings
of the 6146's. I will admit that in a contest the rule changed to "Tune
for maximum smoke and replace all charred components".

Having an SWR bridge is like wearing dark trousers, if you pee your pants,
no one notices - but it gives you a warm feeling. As soon as I become
dictator of the world, I am outlawing them...

"Reg Edwards" wrote in message
...
"nathan" wrote
I have always heard that this is true, and that I should tune antennas
for maximum field strength and not for minimum SWR. Why wouldn't they
occur at the same time?

.................................................. .....

Minimum SWR informs you your transmitter is loaded with the nearest
possible
impedance to 50 ohms.

Maximum field strength informs you your transmitter is sending out maximum
possible power.

There's no way of knowing whether or not the two conditions coincide.

It may occur at maximum field strength that the load on the transmitter
causes distortion and poor efficiency in the PA with excessive internal
volts or amps or watts.

So to avoid flogging the PA or power supply to an early death you should
always tune up to minimum, preferably zero SWR.

You have to balance the probabilities. What are the chances of winning
the
contest before the PA issues smoke.
----
Reg, G4FGQ

w4jle wrote:

" Does a tuner change the SWR of an antenna? Or
does it simply transform an impedence to one that makes the transmitter
happy? Will the maximum field strength coincide with 1:1 SWR at the tuner in
all cases?"

1. A tuner doesn't change the SWR of an antenna. It will change
the SWR of the system to something the transmitter 'likes'.
2. In all cases? Probably not. In 'most' cases? A definite
maybe.
'Doc

preferably zero SWR.

Reg, G4FGQ

How do you get that mr. snotty?
The closest I am able to get is 1 or 1:1
Care to enlighten us dumbells?

BUm

On Thu, 20 Nov 2003 12:47:00 -0500, "w4jle" W4JLE(remove this to
wrote:
Having an SWR bridge is like wearing dark trousers, if you pee your pants,
no one notices - but it gives you a warm feeling.

Not having a SWR meter merely means you can't feel the warm sensation
for the same circumstances ... which may lead to everyone noticing.

(An example of how similes fail.)

73's
Richard Clark, KB7QHC

I'll allow your fellow amateurs to judge who's the dumbell.