[Elecraft] ATU - Internal Tuner

[Don Wilhelm]

Chuck, 'coupler' or 'tuner' is simply a matter of semantics, they are 
both the same thing.  Whether you choose to refer to the remote tuner as 
a coupler or not to provide a distinction or not is your choice, but I 
do not believe that usage is universal.

The purpose of all such devices is to match the antenna to the feedline 
(when located at the antenna feedpoint), or to match the 
antenna/feedline combination to the output requirements of the 
transceiver (when located in the shack).

In the case where the feedline is 50 ohm coax and the match is done at 
the antenna, there is no need for a tuner at the transceiver end since 
the SWR on the coax will be sufficiently low to match the transceiver - 
besides, this technique keeps the feedline losses low.

If inherently low loss feedline (true open wire line is the lowest with 
dry ladder line a close second), there is no need to match the antenna 
to the feedline and all matching can be done at the transition between 
the parallel feedline and coax.

Of course, those who are fortunate to have only resonant coax fed 
antennas, there is no need for a tuner anywhere in the system.

The K3 internal tuner can be put into bypass state when you are using a 
remote tuner.

73,
Don W3FPR

crmabbott at comcast.net wrote:
> Just a thought I have always heard the tuner at the feed point of the 
> antenna defined [SGC] as a coupler.  Because it is making a tank 
> circuit at the feed point of the antenna.    Now the 'Tuner' when it 
> works takes in both the antenna and the coax as what it sees as the 
> load.  The coupler has some trouble tuning if in fact it is far from 
> antenna. I have also heard the coupler is better than tuner and tuner 
> is better than the coupler,  but no matter for this discussion.
>  
> If the radio has an internal tuner and the output of radio is feeding 
> a coupler at the feed point of antenna isn't the system going to be a 
> little odd trying to adjust for each other?  I would think you need a 
> reliable way to lock either one of them out and let signal do a pass 
> through.
>