[TowerTalk] G5RV vs 40M dipole

[Tom Osborne]

One thing I have noticed with the built-in tuner on my radio is that all 
it does is make the radio happy.

The radio shows a 1:1 SWR, but the meter past the radio still shows a 
high SWR, so if there is loss on the line, even though the radio is 
happy, the loss is still there.  I think the tuners just give us a false 
sense of security.  73
Tom W7WHY

On 4/26/2015 9:23 PM, Fuqua, Bill L wrote:
>     Not everyone knows that a tuner only protects the rig. That is the job of a dummy load.
> In fact the tuner matches the impedance of the antenna system to the rig and not only that,
> by doing so providing the antenna with a conjugate match, that is to say the antenna's radiation
> resistance is matched and its reactance is also matched by the equal and opposite reactance thus
> making the antenna system resonant. If the antenna has a radiation resistance of 10 Ohms and
> a capacitive reactance of 100 Ohms the antenna tuner matches it with 10 Ohms real resistance and
> an inductive reactance of 100 Ohms thus providing  maximum energy transfer. While at
> the same time it provides 50 Ohms resistive load for the transmitter.
>    Resonating the antenna system with a tuner is equivalent resonating the antenna. The only difference
> is that there may be some additional losses within the tuner and transmission line which are generally
> minimal at HF frequencies. Also, there is a reduction in bandwidth of the antenna system.
>    Yes it does change the currents and voltages in the antenna. The G5RV was an antenna developed back
> when we had tube transmitters with a PI network output that could accommodate a broad range of
> impedances. It also was made to work on 5 bands.
>    Just about every AM broadcast antenna system has an antenna matching network. It is a shame that
> they don't work.
> 73
> Bill wa4lav