I heard a good one on the radio the other day. A fellow was describing a
dipole and he was feeding it with parallel lines of rg8x to keep it in
balance. Then into a tuner.

That did not bother me, but what made my ears perk up is that he cut the
dipole either longer or shorter (forgot which) so the SWR was about 2.5 to 3
to 1. By doing this he said the signal to noise ratio was a lot beter on
receive.

I think you missed the point.

USING a SWR meter to tune a antenna does nothing to express resonance.

Dipoles by nature are a 1/2 wavelength or wavelengths in size.

The RG 8X was used as phasing lines - was the tuneable matching network.

Maybe what the person intended to say was that they tuned the antenna for a different frequency / hence at the frequency they desired to use, was a poor match with that antenna.

It stands to reason, if the antenna was not resonant, it would not receive as well at X Mhz.

In communications, we want to receive as much as we can possibly receive, unless what you are trying to do is local communications into the one local repeater - since most public service communications takes place on one frequency or one band of frequencies. Police, Fire, Ambulance etc...

When tropospheric ducting takes place, it is not uncommon to hear others communicating on your frequency, even if they are hundreds of miles away - even on 450 MHz...

On 6/28/2012 6:39 PM, Channel Jumper wrote:


The RG 8X was used as phasing lines - was the tuneable matching
network.

I doubt it.. He seems to be feeding a single dipole, using
twin runs of coax as an expensive type of ladder line. :/


Maybe what the person intended to say was that they tuned the antenna
for a different frequency / hence at the frequency they desired to use,
was a poor match with that antenna.

It stands to reason, if the antenna was not resonant, it would not
receive as well at X Mhz.


It would almost surely be a matching issue though. The length
of the dipoles, or being resonant or not, doesn't really matter
too much. Almost any length dipole will radiate almost all
power applied to it. The trick is getting the power to it, and
not turning some into heat in the process.
And reception is reciprocal vs transmit.
I don't buy the claims of better signal to noise ratio.
Adding loss is going to lower the level of all received RF equally.
Actual signals will be reduced at the same ratio as any noise.
So at the end of the day, the s/n ratio should stay the same.

Ralph Mowery wrote:
I heard a good one on the radio the other day. A fellow was describing a
dipole and he was feeding it with parallel lines of rg8x to keep it in
balance. Then into a tuner.

That did not bother me, but what made my ears perk up is that he cut the
dipole either longer or shorter (forgot which) so the SWR was about 2.5 to 3
to 1. By doing this he said the signal to noise ratio was a lot beter on
receive.

Or you can turn down the RF gain and accomplish the same thing on receive
but not effect transmit.