[Elecraft] K3S with Internal ATU(KAT3A) and Remote ATU?

[Jim Brown]

On Thu,8/4/2016 9:16 AM, Ignacy wrote:
> With 43 ft vertical a tuner at the base is critical to performance

It is FAR more complicated than that. Antenna tuners provide a match 
between a transmitter and a feedline, or between an antenna and a 
feedline. Like antennas like the G5RV, a 43 ft vertical is WILDLY 
mismatched to 50 ohms on most bands, which makes serious matching at the 
base important. HOWEVER -- it has been shown that if the feedline is of 
high quality, like 1-2-in hard line; and 2) if it is fairly short (less 
than about 50 ft); and 3) some matching is done at the feedpoint,  a 
tuner in the shack can match the antenna to the transmitter and feedline 
loss will be sufficiently low that it's not an issue.

I've studied the 43-ft vertical, and reported on what I've learned in 
this set of Power Point slides for a talk I did several years ago at 
Pacificon.  http://k9yc.com/43FtVertical.pdf

> and KAT3 may in some cases be detrimental.

I cannot imagine the logic behind this statement.

> Check the signal reports with both antennas. At my QTH verticals nearly
> always are 10db down from dipoles even for DX, except when dipoles have
> nulls.

The relative performance of horizontal and vertical antennas is STRONGLY 
dependent on 1) soil conditions; 2) their height; and 3) for verticals, 
their counterpoise/radial system if they need one. An HF vertical 
mounted at roof level will outperform the same antenna mounted at ground 
level, and the degree of outperformance will depend on soil conditions. 
Some verticals are fundamentally dipoles, and do not need radial 
systems, so they are easy to put on a roof. The R8 and AV640 are 
examples. Other verticals that are designed as quarter wave antennas 
with loading coils DO require radials, so if you put them on a roof, you 
need at least one for each band where plan to transmit, and two per band 
is better.

> In this case your better option is  adding an extra G5RV
> perpendicular to the first G5RV, also fed by flat line.

I'm not at all a fan of antennas like the G5RV, primarily because they 
cannot be choked to kill RX noise. Adding another one would be a bad 
move. Far better are antennas like resonant  fan dipoles fed with coax, 
and yes, if you can, place two at right angles. Resonant, coax-fed 
antennas CAN be effectively choked, so RX noise can be lower. You can't 
work what you can't hear!

73, Jim K9YC