View Single Post
  #14   Report Post  
Old November 20th 03, 05:47 PM
w4jle
 
Posts: n/a
Default

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