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MGFoster wrote:
I'm working QRP (5W max) and I'm construction my own antennas. I've
read that antenna efficiency can be degraded by "high ohmic
connections"
(especially deleterious to QRP ops). I'm assuming that we shouldn't
make potato-sized solder joints when assembling the antenna. So, I
was
wondering what would be the best way to connect various parts of the
antenna?

SNIP

Thanks to everyone who gave advice; very helpful.

The person who stated that "high ohmic connections" were deleterious to
QRP ops was describing his construction of a linear loaded dipole and
the connections to the inductance section of the antenna (see N5ESE's
article on the "Notebook antenna"
http://www.io.com/~n5fc/notebk_ant.htm). This is a small radiation
resistance antenna and could be affected by bad connections.

The balun's connections, described in my original post, will not be
subject to mechanical stress 'cuz it will be bolted down inside a
connection box and protected from the wx.

Thanks & 73
--
MGFoster:::mgf00 at earthlink decimal-point net
Oakland, CA (USA)
** Respond only to this newsgroup. I DO NOT respond to emails **

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MGFoster wrote:

Thanks to everyone who gave advice; very helpful.

The person who stated that "high ohmic connections" were deleterious to
QRP ops was describing his construction of a linear loaded dipole and
the connections to the inductance section of the antenna (see N5ESE's
article on the "Notebook antenna"
http://www.io.com/~n5fc/notebk_ant.htm). This is a small radiation
resistance antenna and could be affected by bad connections.
. . .

Yes, it does have a low radiation resistance:

21 MHz: 31.7 ohms
14 MHz: 11.6 ohms
7 MHz: 2.6 ohms
3.5 MHz: 0.64 ohms
1.8 MHz: 0.17 ohms

And the tuner has a lot of reactance to take care of, from about 180
ohms at 21 MHz to nearly 8000 at 1.8 MHz. If a 1.8 MHz tuner had a coil
with Q = 400, the tuner loss alone would be 20 dB.

My model doesn't show the claimed spectacular rise in radiation
resistance from the meander lines. Replacing them with straight 14 inch
wires just about halves the radiation resistance. That's nearly 3 dB at
the lower frequencies, so nothing to sniff at, but nowhere near the
factor of up to 14 claimed. The meander lines cut the reactance by a
factor of 1-1/2 to 2, which helps the tuner efficiency.

The fact that QSOs can be made with this antenna and QRP is yet another
illustration of just how little radiated power is needed in order to
communicate.

Roy Lewallen, W7EL

MGFoster wrote in
:
....
The person who stated that "high ohmic connections" were deleterious to
QRP ops was describing his construction of a linear loaded dipole and
the connections to the inductance section of the antenna (see N5ESE's
article on the "Notebook antenna"
http://www.io.com/~n5fc/notebk_ant.htm). This is a small radiation
resistance antenna and could be affected by bad connections.

I had a look at that article, and have concerns about many things stated,
and the way in which the author distances himself from some of what is
said.

The effect of linear loading is that the contribution to radiation of
current in a segment of one section of the linear loading is offset to
some lesser or greater extent by the currents in parallel segments. The
heat loss is incurred by the current flowing in all the conductors, but
the radiation effect is diminished.

This mechanism can increase the loss resistance more than it increases
the radiation resistance.

This is contrary to the widely held view that linear loading is
essentially lossless.

Owen